Showing papers in "Circulation-cardiovascular Imaging in 2011"

Dynamic Changes of Edema and Late Gadolinium Enhancement After Acute Myocardial Infarction and Their Relationship to Functional Recovery and Salvage Index

Abstract: Background— Changes in the myocardium in acute ischemia are dynamic and complex, and the characteristics of myocardial tissue on cardiovascular magnetic resonance in the acute setting are not fully defined. We investigated changes in edema and late gadolinium enhancement (LGE) with serial imaging early after acute myocardial infarction, relating these to global and segmental myocardial function at 6 months. Methods and Results— Cardiovascular magnetic resonance scans were performed on 30 patients with ST-elevation–myocardial infarction treated by primary percutaneous coronary intervention at each of 4 time points: 12 to 48 hours; 5 to 7 days; 14 to 17 days; and 6 months. All patients showed edema at 24 hours. The mean volume of edema (% left ventricle) was 37±16 at 24 hours and 39±17 at 1 week, with a reduction to 24±13 ( P <0.01) by 2 weeks. Myocardial segments with edema also had increased signal on LGE at 24 hours (κ=0.77; P <0.001). The volume of LGE decreased significantly between 24 hours and 6 months (27±15% versus 22±12%; P =0.002). Of segments showing LGE at 24 hours, 50% showed resolution by 6 months. In segments with such a reduction in LGE, 65% also showed improved wall motion ( P <0.0001). The area of LGE measured at 6 months correlated more strongly with troponin at 48 hours ( r =0.9; P <0.01) than LGE at 24 hours ( r =0.7). The difference in LGE between 24 hours and 6 months had profound effects on the calculation of salvage index (26±21% at 24 hours versus 42±23% at 6 months; P =0.02). Conclusions— Myocardial edema is maximal and constant over the first week after myocardial infarction, providing a stable window for the retrospective evaluation of area at risk. By contrast, myocardial areas with high signal intensity in LGE images recede over time with corresponding recovery of function, indicating that acutely detected LGE does not necessarily equate with irreversible injury and may severely underestimate salvaged myocardium.

Incremental prognostic value of cardiac computed tomography in coronary artery disease using CONFIRM: COroNary computed tomography angiography evaluation for clinical outcomes: an InteRnational Multicenter registry.

Abstract: Background— Large multicenter studies validating the prognostic value of coronary computed tomographic angiography (CCTA) and left ventricular ejection fraction (LVEF) are lacking. We sought to confirm the independent and incremental prognostic value of coronary artery disease (CAD) severity measured using 64-slice CCTA over LVEF and clinical variables. Methods and Results— A large international multicenter registry (CONFIRM Registry) was queried, and CCTA patients with LVEF data on CCTA were screened. Patients with a history of myocardial infarction, coronary revascularization, or cardiac transplantation were excluded. The National Cholesterol Education Program-Adult Treatment Panel III risk was calculated for each patient, and CCTA was evaluated for CAD severity (normal, nonobstructive, non–high-risk, or high-risk CAD) and LVEF <50%. Patients were followed for an end point of all-cause mortality; 27 125 patients underwent CCTA at 12 participating centers, with a total of 14 064 patients meeting the analysis criteria. Follow-up was available for 13 966 (99.3%) patients (mean follow-up of 22.5 months; 95% confidence interval, 22.3 to 22.7 months). All-cause mortality (271 deaths) occurred in 0.65% of patients without coronary atherosclerosis, 1.99% of patients with nonobstructive CAD, 2.90% of patients with non–high-risk CAD, and 4.95% for patients with high-risk CAD. Multivariable analysis confirmed that LVEF <50% (hazard ratio, 2.74; 95% confidence interval, 2.12 to 3.51) and CAD severity (hazard ratio,1.58; 95% confidence interval, 1.42 to 1.76) were predictors of all-cause mortality, and CAD severity had incremental value over LVEF and clinical variables. Conclusions— Our results demonstrate that CCTA measures of CAD severity and LVEF have independent prognostic value. Incorporation of CAD severity provides incremental value for predicting all-cause death over routine clinical predictors and LVEF in patients with suspected obstructive CAD.

Strain and Strain Rate Echocardiography and Coronary Artery Disease

Abstract: The echocardiographic assessment of regional myocardial function plays a critical role in the diagnosis and management of ischemic heart disease and in most laboratories relies on the visual detection of endocardial wall motion abnormalities and assessment of left ventricular (LV) ejection fraction. However, this approach is subjective and operator dependent, demands complete visualization of the endocardium, and is subject to the vicissitudes of cardiac loading and heart rate. Although estimation of myocardial shortening and thickening reflect the radial mechanics of the heart, the contribution of longitudinal (and to a lesser extent circumferential) myocardial deformation is largely neglected. Thus, there is a need for an objective, comprehensive, noninvasive measurement of myocardial performance and contractility with acceptable interpretative variability. Doppler tissue imaging, which measures the velocity of myocardium (in the longitudinal direction from apical windows and in the radial direction from short-axis scans) during systole and diastole is used to quantify ventricular function and is more sensitive to subtle changes in contractility than ejection fraction.1 However, tissue velocities are affected by translational movement and tethering, making it difficult to discriminate akinetic segments that are pulled (or tethered) from actively contracting segments.2 In addition, velocities are not uniformly distributed across the myocardium, decreasing from base to apex, making difficult the establishment of reference values. Measurements of myocardial strain and strain rate (SR) are newer indices that have the potential to overcome these limitations. Strain and SRs represent the magnitude and rate, respectively, of myocardial deformation, which is an energy-requiring process that occurs in both systole and diastole. Abnormalities of myocardial deformation are seen early in the development of many pathophysiologic states, including ischemia, and thus provide a sensitive means for detecting regional myocardial dysfunction. The objective of this report is to review the use of strain and SR echocardiography in patients …

Evaluation of the left atrial appendage with real-time 3-dimensional transesophageal echocardiography: implications for catheter-based left atrial appendage closure.

Abstract: Background— Precise knowledge of left atrial appendage (LAA) orifice size is crucial for correct sizing of LAA closure devices. The aim of the present study was to determine the performance of real-time 3D transesophageal echocardiography (RT3DTEE) for LAA orifice size assessment, compared with 2D transesophageal echocardiography (2DTEE), and to investigate the impact of atrial fibrillation (AF) on LAA orifice size. Methods and Results— One hundred thirty-seven patients (38 control subjects, 31 with paroxysmal AF, 38 with persistent AF and 30 with permanent AF) underwent 2DTEE and RT3DTEE. Both techniques were used to measure LAA orifice area. Clinically-indicated 64-slice computed tomography (CT) was used as reference technique in 46 patients. Two-dimensional TEE underestimated LAA orifice area, compared with RT3DTEE (1.99±0.94 cm2 versus 3.05±1.27 cm2; P <0.001). RT3DTEE showed higher correlation with CT for the assessment of LAA orifice area, compared with 2DTEE ( r =0.92; 95% confidence interval, 0.85 to 0.95, versus r =0.72; 95% confidence interval, 0.54 to 0.83, respectively). At Bland–Altman analysis, RT3DTEE and 2DTEE underestimated LAA orifice area, compared with CT. However, RT3DTEE showed smaller bias (0.07 cm2 versus 0.72 cm2) and narrower limits of agreement (−0.71 to 0.85 cm2 versus −0.58 to 2.02 cm2) with CT, compared with 2DTEE. Among AF patients, a progressive increase in RT3DTEE-derived LAA orifice area was observed with increasing frequency of AF ( P <0.001). At multivariate analysis, AF and left atrial volume index ( P <0.001 for both) were independently associated with RT3DTEE-derived LAA orifice area. Conclusions— RT3DTEE is more accurate than 2DTEE for the assessment of LAA orifice size. A progressive increase in LAA orifice area is observed with increasing frequency of AF.

Cardiac involvement in patients with muscular dystrophies: magnetic resonance imaging phenotype and genotypic considerations.

Abstract: Muscular dystrophy (MD) connotes a heterogeneous group of inherited disorders characterized by progressive wasting and weakness of the skeletal muscles. In several forms of MD, cardiac dysfunction occurs, and cardiac disease may even be the predominant manifestation of the underlying genetic myopathy. Cardiologists may be unfamiliar with these diseases owing to their low incidence; also, significant advances in respiratory care have only recently unmasked cardiomyopathy as a significant cause of death in MD.1 Early detection of MD-associated cardiomyopathy is important, because institution of cardioprotective medical therapies may slow adverse cardiac remodeling and attenuate heart failure symptoms in these patients.2–6 Although ECG and echocardiography are typically advocated for screening,7,8 cardiovascular magnetic resonance (CMR) has shown promise in revealing early cardiac involvement when standard cardiac evaluation is unremarkable.9,10 This review will focus on 4 groups of skeletal muscle disease most commonly associated with cardiac complications (the Table): (1) dystrophin-associated diseases such as Duchenne and Becker (DMD and BMD, respectively), (2) Emery-Dreifuss MD (EDMD), (3) limb-girdle MD (LGMD), and (4) myotonic dystrophy (DM). View this table: Table. Characteristics of the Types of MD ### Molecular and Genetic Features DMD and BMD are X-linked disorders affecting the synthesis of dystrophin, a large, sarcolemmal protein that is absent in DMD11 and reduced in amount or abnormal in size in BMD patients.12 Dystrophin provides the connection between a large, multimeric complex of glycoproteins in the muscle cell membrane (termed the dystrophin-glycoprotein complex) and intracellular actin filaments (Figure 1), thereby transmitting forces generated by sarcomere contraction to the extracellular matrix.13,14 Correlations between dystrophin mutations and the onset of cardiomyopathy have been noted15; some mutations result in only cardiomyopathy without skeletal myopathy.16 Other proteins not shown in Figure 1 that are particularly involved in both inside-out and outside-in transmission …

Prognostic value and determinants of a hypointense infarct core in T2-weighted cardiac magnetic resonance in acute reperfused ST-elevation-myocardial infarction.

Abstract: Background— A hypointense core of infarcted myocardium in T2-weighted cardiovascular MRI (CMR) has been used as a noninvasive marker for intramyocardial hemorrhage. However, the clinical significance of such findings not yet been established. The aim of this study was to evaluate determinants and prognostic impact of a hypointense infarct core in T2-weighted CMR images, studied in patients after acute, reperfused ST-elevation–myocardial infarction. Methods and Results— We analyzed 346 patients with ST-elevation–myocardial infarction undergoing primary angioplasty <12 hours after symptoms onset. T2-weighted, contrast-enhanced CMR was used for assessment of the area at risk, myocardial salvage, infarct size, hypointense core in T2-weighted images, and late microvascular obstruction. Patients were categorized into 2 groups defined by the presence or absence of a hypointense core. The primary end point of the study was occurrence of major adverse cardiovascular events defined as death, reinfarction, and congestive heart failure within 6 months after infarction. A hypointense core was present in 122 (35%) patients and was associated with larger infarcts, greater amount of microvascular obstruction, less myocardial salvage, and impaired left ventricular function ( P <0.001, respectively). The presence of a hypointense core was a strong univariable predictor of major adverse cardiovascular events (hazard ratio, 2.59; confidence interval, 1.27 to 5.27) and was significantly associated with an increased major adverse cardiovascular events rate (16.4% versus 7.0%, P =0.006) 6 months after infarction. Conclusions— A hypointense infarct core within the area at risk of reperfused infarcted myocardium in T2-weighted CMR is closely related to infarct size, microvascular obstruction, and impaired left ventricular function, with subsequent adverse clinical outcome.

Noninvasive Vascular Function Measurement in the Community Cross-Sectional Relations and Comparison of Methods

Abstract: Background— Several methods of noninvasive vascular function testing have been suggested for cardiovascular risk screening in the community. A direct comparison of the different methods and their relation to classical cardiovascular risk factors in a large cohort is missing. Methods and Results— In 5000 individuals (mean age, 55.5±10.9 years; age range, 35 to 74 years; women, 49.2%) of the population-based Gutenberg Heart Study, we performed simultaneous measurement of flow-mediated dilation (FMD) and peripheral arterial volume pulse determined by infrared photo (reflection index) and pneumatic plethysmography (PAT) and explored their associations. All function measures were recorded at baseline and after reactive hyperemia induced by 5-minute brachial artery occlusion. Correlations between different measures of vascular function were statistically significant but moderate. The strongest association for hyperemic response variables was observed for PAT ratio and FMD (Spearman r =0.17; age- and sex-adjusted partial correlation, 0.068). Classical risk factors explained between 15.8% (baseline reflection index) and 58.4% (brachial artery diameter) of the baseline values but only accounted for 3.2% (reflection index), 15.4% (FMD), and 13.9% (PAT ratio) of the variability of reflective hyperemic response. Regression models varied in their relations to classical risk factors for the individual vascular function measures. Consistently associated with different vascular function methods were age, sex, body mass index, and indicators of hypertension. Peripheral tonometry also showed a relation to fasting glucose concentrations. Conclusions— Noninvasive measures of conduit artery and peripheral arterial function are modestly correlated, differ in their relation to classical cardiovascular risk factors, and may thus reflect different pathologies.

Clinical value of absolute quantification of myocardial perfusion with (15)O-water in coronary artery disease.

Abstract: Background— The standard interpretation of perfusion imaging is based on the assessment of relative perfusion distribution. The limitations of that approach have been recognized in patients with multivessel disease and endothelial dysfunction. To date, however, no large clinical studies have investigated the value of measuring quantitative blood flow and compared that with relative uptake. Methods and Results— One hundred four patients with moderate (30%–70%) pretest likelihood of coronary artery disease (CAD) underwent PET imaging during adenosine stress using 15O-water and dynamic imaging. Absolute myocardial blood flow was calculated from which both standard relative myocardial perfusion images and images scaled to a known absolute scale were produced. The patients and the regions then were classified as normal or abnormal and compared against the reference of conventional angiography with fractional flow reserve. In patient-based analysis, the positive predictive value, negative predictive value, and accuracy of absolute perfusion in the detection of any obstructive CAD were 86%, 97%, and 92%, respectively, with absolute quantification. The corresponding values with relative analysis were 61%, 83%, and 73%, respectively. In region-based analysis, the receiver operating characteristic curves confirmed that the absolute quantification was superior to relative assessment. In particular, the specificity and positive predictive value were low using just relative differences in flow. Only 9 of 24 patients with 3-vessel disease were correctly assessed using relative analysis. Conclusions— The measurement of myocardial blood flow in absolute terms has a significant impact on the interpretation of myocardial perfusion. As expected, multivessel disease is more accurately detected. Clinical Trial Registration— URL: . Unique identifier: [NCT00627172][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00627172&atom=%2Fcirccvim%2F4%2F6%2F678.atom

Diagnostic value of vena contracta area in the quantification of mitral regurgitation severity by color Doppler 3D echocardiography.

Abstract: Background— Accurate quantification of mitral regurgitation (MR) is important for patient treatment and prognosis. Three-dimensional echocardiography allows for the direct measure of the regurgitant orifice area (ROA) by 3D-guided planimetry of the vena contracta area (VCA). We aimed to (1) establish 3D VCA ranges and cutoff values for MR grading, using the American Society of Echocardiography–recommended 2D integrative method as a reference, and (2) compare 2D and 3D methods of ROA to establish a common calibration for MR grading. Methods and Results— Eighty-three patients with at least mild MR underwent 2D and 3D echocardiography. Direct planimetry of VCA was performed by 3D echocardiography. Two-dimensional quantification of MR included 2D ROA by proximal isovelocity surface area (PISA) method, vena contracta width, and ratio of jet area to left atrial area. There were significant differences in 3D VCA among patients with different MR grades. As assessed by receiver operating characteristic analysis, 3D VCA at a best cutoff value of 0.41 cm2 yielded 97% of sensitivity and 82% of specificity to differentiate moderate from severe MR. There was significant difference between 2D ROA and 3D VCA in patients with functional MR, resulting in an underestimation of ROA by 2D PISA method by 27% as compared with 3D VCA. Multivariable regression analysis showed functional MR as etiology was the only predictor of underestimation of ROA by the 2D PISA method. Conclusions— Three-dimensional VCA provides a single, directly visualized, and reliable measurement of ROA, which classifies MR severity comparable to current clinical practice using the American Society of Echocardiography–recommended 2D integrative method. The 3D VCA method improves accuracy of MR grading compared with the 2D PISA method by eliminating geometric and flow assumptions, allowing for uniform clinical grading cutoffs and ranges that apply regardless of etiology and orifice shape.

Abdominal aortic aneurysm growth predicted by uptake of ultrasmall superparamagnetic particles of iron oxide: a pilot study.

Abstract: Background— Abdominal aortic aneurysms are a major cause of death. Prediction of aneurysm expansion and rupture is challenging and currently relies on the simple measure of aneurysm diameter. Using MRI, we aimed to assess whether areas of cellular inflammation correlated with the rate of abdominal aortic aneurysm expansion. Methods and Results— Stable patients (n=29; 27 male; age, 70±5 years) with asymptomatic abdominal aortic aneurysms (4.0 to 6.6 cm) were recruited from a surveillance program and imaged using a 3-T MRI scanner before and 24 to 36 hours after administration of ultrasmall superparamagnetic particles of iron oxide (USPIO). The change in T2* value on T2*-weighted imaging was used to detect accumulation of USPIO within the abdominal aortic aneurysm. Histological examination of aneurysm tissue confirmed colocalization and uptake of USPIO in areas with macrophage infiltration. Patients with distinct mural uptake of USPIO had a 3-fold higher growth rate (n=11, 0.66 cm/y; P =0.020) than those with no (n=6, 0.22 cm/y) or nonspecific USPIO uptake (n=8, 0.24 cm/y) despite having similar aneurysm diameters (5.4±0.6, 5.1±0.5, and 5.0±0.5 cm, respectively; P >0.05). In 1 patient with an inflammatory aneurysm, there was a strong and widespread uptake of USPIO extending beyond the aortic wall. Conclusions— Uptake of USPIO in abdominal aortic aneurysms identifies cellular inflammation and appears to distinguish those patients with more rapidly progressive abdominal aortic aneurysm expansion. This technique holds major promise as a new method of risk-stratifying patients with abdominal aortic aneurysms that extends beyond the simple anatomic measure of aneurysm diameter. Clinical Trial Registration— URL: . Unique identifier: [NCT00794092][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00794092&atom=%2Fcirccvim%2F4%2F3%2F274.atom

Echocardiographic evaluation of hemodynamics in patients with decompensated systolic heart failure.

Abstract: Background— Doppler echocardiography is currently applied for the assessment of left ventricular and right ventricular hemodynamics in patients with cardiovascular disease. However, there are conflicting reports about its accuracy in patients with unstable decompensated heart failure. The objective of this study was to evaluate the accuracy of the technique in patients with unstable heart failure. Methods and Results— Consecutive patients with decompensated heart failure had simultaneous assessment of left ventricular and right ventricular hemodynamics invasively and by Doppler echocardiography. In 79 patients, the noninvasive measurements of stroke volume ( r =0.83, P 15 mm Hg (area under the curve, 0.86 to 0.92). The recent American Society of Echocardiography/European Association of Echocardiography guidelines were highly accurate (sensitivity, 98%; specificity, 91%) in identifying patients with increased wedge pressure. In 12 repeat studies, Doppler echocardiography readily detected the changes in mean wedge pressure ( r =0.75, P =0.005) as well as changes in pulmonary artery systolic pressure and mean right atrial pressure. Conclusions— Doppler echocardiography provides reliable assessment of right and left ventricular hemodynamics in patients with decompensated heart failure.

Adenosine stress high-pitch 128-slice dual-source myocardial computed tomography perfusion for imaging of reversible myocardial ischemia: comparison with magnetic resonance imaging.

Abstract: Background— Coronary computed tomography angiography (CTA) enables accurate anatomic evaluation of coronary artery stenosis but lacks information about hemodynamic significance. The aim of this study was to evaluate 128-slice myocardial CT perfusion (CTP) imaging with adenosine stress using a high-pitch mode, in comparison with cardiac MRI (CMR). Methods and Results— Thirty-nine patients with intermediate to high coronary risk profile underwent adenosine stress 128-slice dual source CTP (128×0.6 mm, 0.28 seconds). Among those, 30 patients (64±10 years, 6% women) also underwent adenosine stress CMR (1.5T). The 2-step CTP protocol consisted of (1) adenosine stress-CTP using a high-pitch factor (3.4) ECG-synchronized spiral mode and (2) rest-CTP/coronary-CTA using either high-pitch (heart rate 63 bpm). Results were compared with CMR and with invasive angiography in 25 patients. The performance of stress-CTP for detection of myocardial perfusion defects compared with CMR was sensitivity, 96%; specificity, 88%; positive predictive value (PPV), 93%; negative predictive value (NPV), 94% (per vessel); and sensitivity, 78%; specificity, 87%; PPV, 83%; NPV, 84% (per segment). The accuracy of stress-CTP for imaging of reversible ischemia compared with CMR was sensitivity, 95%; specificity, 96%; PPV, 95%; and NPV, 96% (per vessel). In 25 patients who underwent invasive angiography, the accuracy of CTA for detection of stenosis >70% was (per segment): sensitivity, 96%; specificity, 88%; PPV, 67%; and NPV, 98.9%. The accuracy improved from 84% to 95% after adding stress CTP to CTA. Radiation exposure of the entire stress/rest CT protocol was only 2.5 mSv. Conclusions— Adenosine-induced stress 128-slice dual-source high-pitch myocardial CTP allows for simultaneously assessment of reversible myocardial ischemia and coronary stenosis, with good diagnostic accuracy as compared with CMR and invasive angiography, at a very low radiation exposure.

Characterization of degenerative mitral valve disease using morphologic analysis of real-time three-dimensional echocardiographic images: objective insight into complexity and planning of mitral valve repair.

Abstract: Background— Presurgical planning of mitral valve (MV) repair in patients with Barlow disease (BD) and fibroelastic deficiency (FED) is challenging because of the inability to assess accurately the complexity of MV prolapse. We hypothesized that the etiology of degenerative MV disease (DMVD) could be objectively and accurately ascertained using parameters of MV geometry obtained by morphological analysis of real-time 3D echocardiographic (RT3DE) images. Methods and Results— Seventy-seven patients underwent transesophageal RT3DE study: 57 patients with DMVD studied intraoperatively (28 BD, 29 FED classified during surgery) and 20 patients with normal MV who were used as control subjects (NL). MVQ software (Philips) was used to measure parameters of annular dimensions and geometry and leaflet surface area, including billowing volume and height. The Student t test and multinomial logistic regression was performed to identify parameters best differentiating DMVD patients from normal as well as FED from BD. Morphological analysis in the DMVD group revealed a progressive increase in multiple parameters from NL to FED to BD, allowing for accurate diagnosis of these entities. The strongest predictors of the presence of DMVD included billowing height and volume. Three-dimensional billowing height with a cutoff value of 1.0 mm differentiated DMVD from NL without overlap, and billowing volume with a cutoff value 1.15 mL differentiated between FED and BD without overlap. Conclusions— Morphological analysis as a form of decision support in assessing MV billowing revealed significant quantifiable differences between NL, FED, and BD patients, allowing accurate classification of the etiology of MV prolapse and determination of the anticipated complexity of repair.

Established and novel clinical applications of diastolic function assessment by echocardiography.

Abstract: A cardiac cycle consists of systolic (contraction) and diastolic (relaxation and filling) phases that are linked closely together for optimal function of the heart. Normal diastolic function allows adequate filling of the heart without an excessive increase in diastolic filling pressure both in the resting state and with stress or exertion.1 The diastolic phase is remarkably well designed to ensure that the ventricle is optimally filled for a given clinical condition.2 Basically, at the end of systole, left ventricular (LV) relaxation begins as an initial diastolic process, and LV pressure falls rapidly as the LV expands. This relaxation phase is accompanied by active movement of the mitral annulus away from the apex. The velocity of LV dilatation and mitral annular movement during early diastole correlates well with how fast the LV fills and relaxes, respectively.3,4 Myocardial relaxation continues during early diastole to reach the minimal LV diastolic pressure, which helps with “sucking” or “pulling” the blood actively into the LV (Figure 1, online-only Data Supplement Video 1A). The minimal LV diastolic pressure or completion of relaxation normally occurs by 3.5 times the value of tau—the time constant of relaxation (normal <45 ms)—after the mitral opening.5 LV pressure then rises to be equilibrated with left atrial (LA) pressure, at which time the early diastolic filling decelerates to close the mitral valve until the time of atrial contraction when LA pressure increases to initiate the late filling to complete diastole (Figure 1, online-only Data Supplement Video 1B). Figure 1. Top, Schematic diagram of mitral inflow and mitral medial annulus velocities from normal to progressive stages of diastolic dysfunction. Mitral inflow E is sensitive to preload, becoming higher with shorter deceleration time (time from the peak to the baseline) as diastolic function becomes worse with increasing filling …

Association of imaging markers of myocardial fibrosis with metabolic and functional disturbances in early diabetic cardiomyopathy.

Abstract: Background— Metabolic and vascular disturbances contribute to diabetic cardiomyopathy, but the role of interstitial fibrosis in early disease is unproven. We sought to assess the relationship between imaging markers of diffuse fibrosis and myocardial dysfunction and to link this to possible causes of early diabetic cardiomyopathy. Methods and Results— Hemodynamic and metabolic data were measured in 67 subjects with type 2 diabetes mellitus (age 60±10 years) with no cardiac symptoms. Myocardial function was evaluated with standard echocardiography and myocardial deformation; ischemia was excluded by exercise echocardiography. Calibrated integrated backscatter was calculated from parasternal long-axis views. T1 mapping was performed after contrast with a modified Look-Locker technique using saturation recovery images. Amino-terminal propeptides of procollagens type I and III, as well as the carboxy-terminal propeptide of procollagen type I, were assayed to determine collagen turnover. Subjects with abnormal early diastolic tissue velocity (Em) had shorter postcontrast T1 values ( P =0.042) and higher calibrated integrated backscatter ( P =0.007). They were heavier ( P =0.003) and had worse exercise capacity ( P <0.001), lower insulin sensitivity ( P =0.003), and blunted systolic tissue velocity ( P =0.05). Postcontrast T1 was associated with diastolic dysfunction (Em r =0.28, P =0.020; E/Em r =−0.24, P =0.049), impaired exercise capacity ( r =0.30, P =0.016), central adiposity ( r =−0.26, P =0.046), blood pressure (systolic r =−0.30, P =0.012; diastolic r =−0.49, P <0.001), and insulin sensitivity ( r =0.30, P =0.037). The association of T1 with E/Em (β=−0.31, P =0.017) was independent of blood pressure and metabolic disturbance. Amino-terminal propeptide of procollagens type III was linked to diastolic dysfunction (Em r =−0.32, P =0.008) and calibrated integrated backscatter ( r =0.30, P =0.015) but not T1 values. Conclusions— The association between myocardial diastolic dysfunction, postcontrast T1 values, and metabolic disturbance supports that diffuse myocardial fibrosis is an underlying contributor to early diabetic cardiomyopathy.

Dilatation and dysfunction of the right ventricle immediately after ultraendurance exercise: exploratory insights from conventional two-dimensional and speckle tracking echocardiography.

Abstract: BACKGROUND: Running an ultramarathon has been shown to have a transient negative effect on right ventricular (RV) and left ventricular (LV) function. Additionally, recent findings suggested that ultraendurance athletes may be more at risk of developing a RV cardiomyopathy. The standard echocardiographic assessment of RV function is problematic; however, the introduction of ultrasonic speckle tracking technology has the potential to yield a comprehensive evaluation of RV longitudinal function, providing new insights into this phenomenon. Thus, the primary aim of this exploratory study was to evaluate comprehensively RV structure and function after a 161-km ultramarathon and establish whether changes in the RV are associated with alterations in LV function. METHODS AND RESULTS: Myocardial speckle tracking echocardiograms of the RV and LV were obtained before and immediately after a 161-km ultramarathon in 16 healthy adults. Standard echocardiography was used to determine RV size and function and LV eccentricity index. Speckle tracking was used to determine the temporal evaluation of indices of RV and LV function. RV size was significantly increased postrace (RV outflow, 32 to 35 mm, P=0.002; RV inflow, 42 to 45 mm, P=0.027) with an increase in LV eccentricity index (1.03 to 1.13, P=0.006). RV strain (e) was significantly reduced postrace (-27% to -24%, P=0.004), but there was no change in the rates of e. Peak e in all planes of LV motion were reduced postrace (longitudinal, -18.3 to -16.3%, P=0.012; circumferential, -20.2% to -15.7%, P=0.001; radial, 53.4% to 40.3%, P=0.009). Changes in RV size and function correlated with diastolic strain rates in the LV. CONCLUSIONS: This exploratory study demonstrates RV dilatation and reduction in function after an ultramarathon. Further research is warranted to elucidate the mechanisms responsible for these findings. It is not clear what clinical impact might result from consecutive bouts of postexercise RV dysfunction.

Echocardiographic indices do not reliably track changes in left-sided filling pressure in healthy subjects or patients with heart failure with preserved ejection fraction

Abstract: Background— In select patient populations, Doppler echocardiographic indices may be used to estimate left-sided filling pressures. It is not known, however, whether changes in these indices track changes in left-sided filling pressures within individual healthy subjects or patients with heart failure with preserved ejection fraction (HFpEF). This knowledge is important because it would support, or refute, the serial use of these indices to estimate changes in filling pressures associated with the titration of medical therapy in patients with heart failure. Methods and Results— Forty-seven volunteers were enrolled: 11 highly screened elderly outpatients with a clear diagnosis of HFpEF, 24 healthy elderly subjects, and 12 healthy young subjects. Each patient underwent right heart catheterization with simultaneous transthoracic echo. Pulmonary capillary wedge pressure (PCWP) and key echo indices (E/e′ and E/Vp) were measured at two baselines and during 4 preload altering maneuvers: lower body negative pressure −15 mm Hg; lower body negative pressure −30 mm Hg; rapid saline infusion of 10 to 15 mL/kg; and rapid saline infusion of 20 to 30 mL/kg. A random coefficient mixed model regression of PCWP versus E/e′ and PCWP versus E/Vp was performed for (1) a composite of all data points and (2) a composite of all data points within each of the 3 groups. Linear regression analysis was performed for individual subjects. With this protocol, PCWP was manipulated from 0.8 to 28.8 mm Hg. For E/e′, the composite random effects mixed model regression was PCWP=0.58×E/e′+7.02 ( P <0.001), confirming the weak but significant relationship between these 2 variables. Individual subject linear regression slopes (range, −6.76 to 11.03) and r 2 (0.00 to 0.94) were highly variable and often very different than those derived for the composite and group regressions. For E/Vp, the composite random coefficient mixed model regression was PCWP=1.95×E/Vp+7.48 ( P =0.005); once again, individual subject linear regression slopes (range, −16.42 to 25.39) and r 2 (range, 0.02 to 0.94) were highly variable and often very different than those derived for the composite and group regressions. Conclusions— Within individual subjects the noninvasive indices E/e′ and E/Vp do not reliably track changes in left-sided filling pressures as these pressures vary, precluding the use of these techniques in research studies with healthy volunteers or the titration of medical therapy in patients with HFpEF.

Prognostic value of routine cardiac magnetic resonance assessment of left ventricular ejection fraction and myocardial damage: an international, multicenter study.

Abstract: Background— Cardiac magnetic resonance (CMR) is considered the reference standard for assessment of left ventricular ejection fraction (LVEF) and myocardial damage. However, few studies have evaluated the relationship between CMR findings and patient outcome, and of these, most are small and none multicenter. We performed an international, multicenter study to assess the prognostic importance of routine CMR in patients with known or suspected heart disease. Methods and Results— From 10 centers in 6 countries, consecutive patients undergoing routine CMR assessment of LVEF and myocardial damage by cine and delayed-enhancement imaging (DE-CMR), respectively, were screened for enrollment. Clinical data, CMR protocol information, and findings were collected at all sites and submitted to the data coordinating center for verification of completeness and analysis. The primary end point was all-cause mortality. A total of 1560 patients (age, 59±14 years; 70% men) were enrolled. Mean LVEF was 45±18%, and 1049 (67%) patients had hyperenhanced tissue (HE) on DE-CMR indicative of damage. During a median follow-up time of 2.4 years (interquartile range, 1.2, 2.9 years), 176 (11.3%) patients died. Patients who died were more likely to be older ( P 4 segments) had reduced survival compared to patients with below- or at-median HE ( P =0.02). Conclusions— Both LVEF and amount of myocardial damage as assessed by routine CMR are independent predictors of all-cause mortality. Even in patients with near-normal LVEF, significant damage identifies a cohort with a high risk for early mortality.

Quantitative assessment of artifacts on cardiac magnetic resonance imaging of patients with pacemakers and implantable cardioverter-defibrillators.

Abstract: Background— The safety and clinical utility of MRI at 1.5 T in patients with cardiac implantable devices such as pacemakers (PM) and implantable cardioverter-defibrillators (ICD) have been reported. This study aims to evaluate the extent of artifacts on cardiac magnetic resonance (CMR) in patients with PM and ICD (PM/ICD). Methods and Results— A total of 71 CMR studies were performed with an established safety protocol in patients with prepectoral PM/ICD. The artifact area around the PM/ICD generator was measured in all short-axis (SA), horizontal (HLA), and vertical long-axis (VLA) SSFP cine planes. The location and extent of artifacts were also assessed in all SA (20 sectors per plane), HLA, and VLA (6 sectors per plane) late gadolinium-enhanced CMR (LGE-CMR) planes. The artifact area on cine CMR was significantly larger with ICD versus PM generators in each plane ( P <0.001, respectively). In patients with left-sided ICD or biventricular ICD systems, the percentages of sectors with any artifacts on LGE-CMR were 53.7%, 48.0%, and 49.2% in SA, HLA, and VLA planes, respectively. Patients with left-sided PM or right-sided PM/ICD had fewer artifacts. Anterior and apical regions were severely affected by artifact caused by left-sided PM/ICD generators. Conclusions— In contrast to patients with right-sided PM/ICD and left-sided PM, the anterior and apical left ventricle can be affected by susceptibility artifacts in patients with left-sided ICD. Artifact reduction methodologies will be necessary to improve the performance of CMR in patients with left sided ICD systems.

Assessment of diffuse myocardial fibrosis in rats using small-animal Look-Locker inversion recovery T1 mapping.

Abstract: Background— The concentration of gadopentetate dimeglumine in myocardium and blood can be assessed from T1 measurements and can be used to calculate the extracellular volume (ECV) of the myocardium. We hypothesized that diffuse myocardial fibrosis in a small-animal model could be quantitatively assessed by measuring myocardial ECV using small-animal Look-Locker inversion recovery T1 mapping. Methods and Results— Sprague-Dawley rats (n=10) were subjected to continuous angiotensin-2 (AT2) infusion for 2 weeks via a subcutaneously implanted minipump system. Magnetic resonance imaging (MRI) was performed both before and after AT2 infusion. The MRI protocol included multislice cine imaging and before-and-after contrast small-animal Look-Locker inversion recovery T1 mapping and late gadolinium enhancement imaging. Myocardial ECV was calculated from hematocrit and T1 values of blood and myocardium. During the course of AT2 infusion, the mean±SD systolic blood pressure increased from 122±10.9 to 152±27.5 mm Hg ( P =0.003). Normalized heart weight was significantly higher in AT2-treated animals than in control littermates ( P =0.033). Cine MRI documented concentric left ventricular hypertrophy. Postcontrast myocardial T1 times were shortened after treatment (median [interquartile range], 712 [63] versus 820 [131] ms; P =0.002). Myocardial ECV increased from 17.2% (4.3%) before to 23.0% (6.2%) after AT2 treatment ( P =0.031), which was accompanied by perivascular fibrosis and microscarring on myocardial histological analysis. There was a moderate level of correlation between ECV and collagen volume fraction, as assessed by histological analysis ( r =0.69, P =0.013). Conclusions— In a small-animal model of left ventricular hypertrophy, contrast-enhanced T1 mapping can be used to detect diffuse myocardial fibrosis by quantification of myocardial ECV.

Echocardiographic variables after left ventricular assist device implantation associated with adverse outcome.

Abstract: Background— Operative mortality after left ventricular assist device (LVAD) implantation is heavily influenced by patient selection and the technical difficulty of surgery. However, how we treat our patients and LVAD setting may affect the patient outcome beyond this period. We postulated that the presence of echocardiographic variables 1 month after surgery suggesting appropriate degree of LV unloading and an adequate forward flow would be important in determining clinical outcomes after the initial successful LVAD implantation. Methods and Results— We retrospectively analyzed various variables in echocardiographic examinations performed 30 days after LVAD implant in 76 consecutive patients receiving continuous flow device for their association with a compound end point (90-day mortality, readmission for heart failure, or New York Heart Association class III or higher at the end of the 90-day period). The echocardiographic associations examined included estimated LVAD flow, with and without native LV contribution, interventricular septal position, the status of aortic valve opening, an estimated left atrial pressure (ELAP), the mitral flow E-wave deceleration time, and the ratio of deceleration time to E-wave velocity (mitral deceleration index \[MDI]). Four patients died during the 30- to 90-day period, 6 patients were readmitted for heart failure, and 25 patients were considered to have New York Heart Association class III or higher at the end of the 90-day period. Variables associated with adverse outcome included increased ELAP (odds ratio, 1.30 [1.16–1.48]; P <0.0001), MDI <2 ms/[cm/s\] (odds ratio, 4.4 implantation [1.22–18]; P =0.02) and decreased tricuspid lateral annulus velocity (odds ratio, 0.70 implantation [0.48–0.95]; P =0.02). A leftward deviation of interventricular septum was associated with a worse outcome (odds ratio, 3.03 implantation [1.21–13.3]; P =0.01). Conclusions— Mortality and heart failure after LVAD surgery appear to be predominantly determined by echocardiographic evidence of inefficient unloading of the left ventricle and persistence of right ventricular dysfunction. Increased estimated LA pressure and short MDI are associated with worse mid term outcome. Leftward deviation of the septum is associated with worse outcome as well.

Bright-blood T2-weighted MRI has higher diagnostic accuracy than dark-blood short tau inversion recovery MRI for detection of acute myocardial infarction and for assessment of the ischemic area at risk and myocardial salvage.

Abstract: Background— T2-Weighted MRI reveals myocardial edema and enables estimation of the ischemic area at risk and myocardial salvage in patients with acute myocardial infarction (MI). We compared the diagnostic accuracy of a new bright-blood T2-weighted with a standard black blood T2-weighted MRI in patients with acute MI. Methods and Results— A breath-hold, bright-blood T2-weighted, Acquisition for Cardiac Unified T2 Edema pulse sequence with normalization for coil sensitivity and a breath-hold T2 dark-blood short tau inversion recovery sequence were used to depict the area at risk in 54 consecutive acute MI patients. Infarct size was measured on gadolinium late contrast enhancement images. Compared with dark-blood T2-weighted MRI, consensus agreements between independent observers for identification of myocardial edema were higher with bright-blood T2-weighted MRI when evaluated per patient ( P <0.001) and per segment of left ventricle ( P <0.001). Compared with bright-blood T2-weighted MRI, dark-blood T2-weighted MRI underestimated the area at risk compared with infarct size ( P <0.001). The 95% limits of agreement for interobserver agreements for the ischemic area at risk and myocardial salvage were wider with dark-blood T2-weighted MRI than with bright-blood T2-weighted MRI. Bright blood enabled more accurate identification of the culprit coronary artery with correct identification in 94% of cases compared with 61% for dark blood ( P <0.001). Conclusions— Bright-blood T2-weighted MRI has higher diagnostic accuracy than dark-blood T2-weighted MRI. Additionally, dark-blood T2-weighted MRI may underestimate area at risk and myocardial salvage.

A prospective pilot study to evaluate the relationship between acute change in left ventricular synchrony after cardiac resynchronization therapy and patient outcome using a single-injection gated SPECT protocol.

Abstract: Background— There are ongoing efforts to optimize patient selection criteria for cardiac resynchronization therapy (CRT). In this regard, the relationship between acute change in left ventricular synchrony (LV) after CRT and patient outcome remains undefined. Methods and Results— A novel protocol was designed to evaluate acute change in left LV synchrony after CRT using phase analysis of standard gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging with a single injection of radiotracer and prospectively applied to 44 patients undergoing CRT. Immediately after CRT, 18 (41%), 11 (25%), and 15 (34%) patients had an improvement, no change, or a worsening in LV synchrony. An algorithm incorporating the presence of baseline dyssynchrony, myocardial scar burden, and lead concordance predicted acute improvement or no change in LV synchrony with 72% sensitivity, 93% specificity, 96% positive predictive value, and 64% negative predictive value and had 96% negative predictive value for acute deterioration in synchrony. Over a follow-up period of 9.6±6.8 months, patients who had an acute deterioration in synchrony after CRT had a higher composite event rate of death, heart failure hospitalizations, appropriate defibrillator discharges, and CRT device deactivation for worsening heart failure symptoms, compared with patients who had an improvement or no change [hazard ratio, 4.6 (1.3 to 16.0); log rank test; P =0.003]. Conclusions— In this single-center pilot study, phase analysis of gated SPECT was successfully used to predict acute change in LV synchrony and patient outcome after CRT.

Evaluation of LMI1195, a Novel 18F-Labeled Cardiac Neuronal PET Imaging Agent, in Cells and Animal Models

Abstract: Background— Heart failure has been associated with impaired cardiac sympathetic neuronal function. Cardiac imaging with radiolabeled agents that are substrates for the neuronal norepinephrine transporter (NET) has demonstrated the potential to identify individuals at risk of cardiac events. N -[3-Bromo-4-(3-[18F]fluoro-propoxy)-benzyl]-guanidine (LMI1195) is a newly developed 18F-labeled NET substrate designed to allow cardiac neuronal imaging with the high sensitivity, resolution, and quantification afforded by positron emission tomography (PET). Methods and Results— LMI1195 was evaluated in comparison with norepinephrine (NE) in vitro and 123I-meta-iodobenzylguanidine (MIBG) in vivo. The affinity (Ki) of LMI1195 for NET was 5.16±2.83 μmol/L, similar to that of NE (3.36±2.77 μmol/L) in a cell membrane–binding assay. Similarly, LMI1195 uptake kinetics examined in a human neuroblastoma cell line had Km and Vmax values of 1.44±0.76 μmol/L and 6.05±3.09 pmol/million cells per minute, comparable to NE (2.01±0.85 μmol/L and 6.23±1.52 pmol/million cells per minute). In rats, LMI1195 heart uptake at 15 and 60 minutes after intravenous administration was 2.36±0.38% and 2.16±0.38% injected dose per gram of tissue (%ID/g), similar to 123I-MIBG (2.14±0.30 and 2.19±0.27%ID/g). However, the heart to liver and lung uptake ratios were significantly higher for LMI1195 than for 123I-MIBG. In rabbits, desipramine (1 mg/kg), a selective NET inhibitor, blocked LMI1195 heart uptake by 82%, which was more effective than 123I-MIBG (53%), at 1 hour after dosing. Sympathetic denervation with 6-hydroxydopamine, a neurotoxin, resulted in a marked (79%) decrease in LMI1195 heart uptake. Cardiac PET imaging with LMI1195 in rats, rabbits, and nonhuman primates revealed clear myocardium with low radioactivity levels in the blood, lung, and liver. Imaging in rabbits pretreated with desipramine showed reduced heart radioactivity levels in a dose-dependent manner. Additionally, imaging in sympathetically denervated rabbits resulted in low cardiac image intensity with LMI1195 but normal perfusion images with flurpiridaz F 18, a PET myocardial perfusion imaging agent. In nonhuman primates pretreated with desipramine (0.5 mg/kg), imaging with LMI1195 showed a 66% decrease in myocardial uptake. In a rat model of heart failure, the LMI1195 cardiac uptake decreased as heart failure progressed. Conclusions— LMI1195 is a novel 18F imaging agent retained in the heart through the NET and allowing evaluation of the cardiac sympathetic neuronal function by PET imaging.

Prognostic value of coronary computed tomographic angiography in comparison with calcium scoring and clinical risk scores.

Abstract: Background— Several studies have demonstrated a high accuracy of coronary computed tomography angiography (CCTA) for detection of obstructive coronary artery disease (CAD), whereas some studies have also shown a good prediction of cardiac events. However, it remains to be proven whether CCTA is better predictive of events than conventional risk scores or calcium scoring. Therefore, we compared CCTA with calcium scoring and clinical risk scores for the ability to predict cardiac events. Methods and Results— Patients (n=2223) with suspected CAD undergoing CCTA were followed up for a median of 28 months. The end point was the occurrence of cardiac events (cardiac death, nonfatal myocardial infarction, unstable angina requiring hospitalization, and coronary revascularization later than 90 days after CCTA). Patients with obstructive CAD had a significantly higher event rate (2.9% per year; 95% confidence interval, 2.1 to 4.0) than those without obstructive CAD, having an event rate 0.3% per year (95% confidence interval, 0.1 to 0.5; hazard ratio, 13.5; 95% confidence interval, 6.7 to 27.2; P <0.001). CCTA had significant incremental predictive value when compared with calcium scoring, both with scores assessing the degree of stenosis ( P <0.001) and with scores assessing the number of diseased coronary segments ( P =0.027). Conclusions— In patients with suspected CAD, CCTA not only detects coronary stenosis but also improves prediction of cardiac events over and above conventional risk scores and calcium scoring. This may result in a reclassification of cardiovascular risk in a substantial proportion of patients.

Left atrial size is a potent predictor of mortality in mitral regurgitation due to flail leaflets: results from a large international multicenter study.

Abstract: Background— Left atrium (LA) enlargement is common in organic mitral regurgitation (MR) and is an emerging prognostic indicator. However, outcome implications of LA enlargement have not been analyzed in the context of routine clinical practice and in a multicenter study. Methods and Results— The Mitral Regurgitation International DAtabase (MIDA) registry enrolls patients with organic MR due to flail leaflets, diagnosed in routine clinical practice, in 5 US and European centers. We investigated the relation between LA diameter and mortality under medical treatment and after mitral surgery in 788 patients in sinus rhythm (64±12 years; median LA, 48 [43 to 52] mm). LA diameter was independently associated with survival after diagnosis (hazard ratio, 1.08 [1.04 to 1.12] per 1 mm increment). Compared with patients with LA 0.20). Mitral surgery was associated with greater survival benefit in patients with LA ≥55 mm compared with LA <55 mm ( P for interaction, 0.008). Conclusions— In MR caused by flail leaflets, LA diameter ≥55 mm is associated with increased mortality under medical treatment, independent of the presence of symptoms or left ventricular dysfunction.

Targeted imaging of the spatial and temporal variation of matrix metalloproteinase activity in a porcine model of postinfarct remodeling: relationship to myocardial dysfunction.

Abstract: Background— Matrix metalloproteinases (MMPs) are known to modulate left ventricular (LV) remodeling after a myocardial infarction (MI). However, the temporal and spatial variation of MMP activation and their relationship to mechanical dysfunction after MI remain undefined. Methods and Results— MI was surgically induced in pigs (n=23) and cine magnetic resonance (MR) and dual-isotope hybrid single-photon emission CT (SPECT)/CT imaging obtained using thallium-201 and a technetium-99m-labeled MMP targeted tracer (99mTc-RP805) at 1, 2, and 4 weeks post-MI along with controls (n=5). Regional myocardial strain was computed from MR images and related to MMP zymography and ex vivo myocardial 99mTc-RP805 retention. MMP activation as assessed by in vivo and ex vivo 99mTc-RP805 imaging and retention studies was increased nearly 4-fold within the infarct region at 1 week post-MI and remained elevated up to 1 month post-MI. The post-MI change in LV end-diastolic volumes was correlated with MMP activity (y=31.34e0.48x, P =0.04). MMP activity was increased within the border and remote regions early post-MI, but declined over 1 month. There was a high concordance between regional 99mTc-RP805 uptake and ex vivo MMP-2 activity. Conclusions— A novel, multimodality, noninvasive hybrid SPECT/CT imaging approach was validated and applied for in vivo evaluation of MMP activation in combination with cine MR analysis of LV deformation. Increased 99mTc-RP805 retention was seen throughout the heart early post-MI and was not purely a reciprocal of thallium-201 perfusion. The 99mTc-RP805 SPECT/CT imaging may provide unique information regarding regional myocardial MMP activation and predict late post-MI LV remodeling.

PET imaging may provide a novel biomarker and understanding of right ventricular dysfunction in patients with idiopathic pulmonary arterial hypertension.

Abstract: Background— The clinical course in pulmonary arterial hypertension (PAH) is variable, and there is limited information on the determinants and progression of right ventricular (RV) dysfunction. The objective is to develop PET metabolic imaging of the RV as a noninvasive tool in patients with PAH. Methods and Results— We performed PET scanning in 16 patients with idiopathic PAH (age, 41±14 years, 82% women) using 13N-NH3 for perfusion imaging and 18F-fluorodeoxyglucose for metabolic imaging. The myocardium was divided into 6 regions of interest (3 left ventricular [LV], 3 RV), and time-activity curves were generated. A 2- compartment model was used to calculate myocardial blood flow (MBF), and Patlak analysis was used to calculate the rate of myocardial glucose uptake (MGU). All patients underwent cardiac catheterization, cardiac MRI, and cardiopulmonary exercise testing with gas exchange. MBF, MGU, and the ratio of RV/LV MGU were correlated to clinical parameters. Pulmonary artery (PA) pressure was 79±19/30±8 mm Hg (mean, 48±10 mm Hg). MBF was 0.84±0.33 mL/g per minute for the LV and 0.45±0.14 mL/g per minute for the RV. Mean MGU was 136±72 nmol/g per minute for the LV and 96±69 nmol/g per minute for the RV. The ratio of RV/LV MGU correlated significantly with PA systolic ( r =0.75, P =0.0085) and mean ( r =0.87, P =0.001) pressure and marginally with maximum oxygen consumption ( r =−0.59, P =0.05). RV free wall MGU also correlated well with mean PA pressure ( r =0.66, P =0.03). Conclusions— PET scanning with 13N-NH3 and 18F-fluorodeoxyglucose is a feasible modality for quantifying RV blood flow and metabolism in patients with idiopathic PAH.

Intravascular detection of the vulnerable plaque.

Abstract: Coronary heart disease (CHD) remains the leading cause of death in the United States, and an estimated 1.4 million Americans have a heart attack each year. Over the past 2 decades, the concept of the “vulnerable plaque” (VP) being responsible for the majority of acute coronary syndromes (ACS) has become widely accepted. Coincidentally, there has been rapid expansion of coronary imaging modalities, both invasive and noninvasive, seeking the ability to detect high-risk plaques before their disruption and formation of occlusive thrombus. Histological characteristics of the plaques that are vulnerable to rupture are thin fibrous cap (<65 μm), large lipid pool, and activated macrophages near the fibrous cap, all of which can be detected with high-resolution coronary imaging.1 Cellular mechanisms associated with plaque instability include inflammation, reduced collagen synthesis, local overexpression of collagenase, and smooth muscle cell apoptosis. These pathological processes can alter the plaque surface and its mechanical properties, which also have been targets of recent research. Noninvasive tests, such as CT and MRI are limited by low resolution and are unable to visualize most of the features of VP. At present, only intravascular modalities can potentially distinguish VP from benign types of plaques. In this review, we focus on the recent data from the various types of intravascular modalities currently available or in development and compare their advantages and limitations. Coronary plaque develops eccentrically, and increasing plaque volume induces positive remodeling of the vessel, resulting in external elastic membrane expansion and preservation of luminal area. Coronary angiography only visualizes the coronary lumen and does not provide any information about the characteristics of the arterial wall and its contents. For this reason, coronary angiography has failed as a diagnostic modality for detection of VP, which often causes only modest luminal narrowing. Various histological plaque components have been targeted as …

Regional Thicknesses and Thickening of Compacted and Trabeculated Myocardial Layers of the Normal Left Ventricle Studied by Cardiovascular Magnetic Resonance

Abstract: Background—We used cardiovascular magnetic resonance (CMR) to study normal left ventricular (LV) trabeculation as a basis for differentiation from pathological noncompaction. Methods and Results—Th...