Showing papers by "Steffen E. Petersen published in 2013"

Global and regional left ventricular myocardial deformation measures by magnetic resonance feature tracking in healthy volunteers: comparison with tagging and relevance of gender

Abstract: Feature Tracking software offers measurements of myocardial strain, velocities and displacement from cine cardiovascular magnetic resonance (CMR) images. We used it to record deformation parameters in healthy adults and compared values to those obtained by tagging. We used TomTec 2D Cardiac Performance Analysis software to derive global, regional and segmental myocardial deformation parameters in 145 healthy volunteers who had steady state free precession (SSFP) cine left ventricular short (basal, mid and apical levels) and long axis views (horizontal long axis, vertical long axis and left ventricular out flow tract) obtained on a 1.5 T Siemens Sonata scanner. 20 subjects also had tagged acquisitions and we compared global and regional deformation values obtained from these with those from Feature Tracking. For globally averaged measurements of strain, only those measured circumferentially in short axis slices showed reasonably good levels of agreement between FT and tagging (limits of agreement −0.06 to 0.04). Longitudinal strain showed wide limits of agreement (−0.16 to 0.03) with evidence of overestimation of strain by FT relative to tagging as the mean of both measures increased. Radial strain was systematically overestimated by FT relative to tagging with very wide limits of agreement extending to as much as 100% of the mean value (−0.01 to 0.23). Reproducibility showed similar relative trends with acceptable global inter-observer variability for circumferential measures (coefficient of variation 4.9%) but poor reproducibility in the radial direction (coefficient of variation 32.3%). Ranges for deformation parameters varied between basal, mid and apical LV levels with higher levels at base compared to apex, and between genders by both FT and tagging. FT measurements of circumferential but not longitudinally or radially directed global strain showed reasonable agreement with tagging and acceptable inter-observer reproducibility. We record provisional ranges of FT deformation parameters at global, regional and segmental levels. They show evidence of variation with gender and myocardial region in the volunteers studied, but have yet to be compared with tagging measurements at the segmental level.

European cardiovascular magnetic resonance (EuroCMR) registry – multi national results from 57 centers in 15 countries

Abstract: The EuroCMR registry sought to evaluate indications, image quality, safety and impact on patient management of clinical routine CMR in a multi-national European setting. Furthermore, interim analysis of the specific protocols should underscore the prognostic potential of CMR. Multi-center registry with consecutive enrolment of patients in 57 centers in 15 countries. More than 27000 consecutive patients were enrolled. The most important indications were risk stratification in suspected CAD/Ischemia (34.2%), workup of myocarditis/cardiomyopathies (32.2%), as well as assessment of viability (14.6%). Image quality was diagnostic in more than 98% of cases. Severe complications occurred in 0.026%, always associated with stress testing. No patient died during or due to CMR. In 61.8% CMR findings impacted on patient management. Importantly, in nearly 8.7% the final diagnosis based on CMR was different to the diagnosis before CMR, leading to a complete change in management. Interim analysis of suspected CAD and risk stratification in HCM specific protocols revealed a low rate of adverse events for suspected CAD patients with normal stress CMR (1.0% per year), and for HCM patients without LGE (2.7% per year). The most important indications in Europe are risk stratification in suspected CAD/Ischemia, work-up of myocarditis and cardiomyopathies, as well as assessment of viability. CMR imaging is a safe procedure, has diagnostic image quality in more than 98% of cases, and its results have strong impact on patient management. Interim analyses of the specific protocols underscore the prognostic value of clinical routine CMR in CAD and HCM. The EuroCMR registry sought to evaluate indications, image quality, safety and impact on patient management of clinical routine CMR in a multi-national European setting in a large number of cases (n > 27000). Based on our data CMR is frequently performed in European daily clinical routine. The most important indications in Europe are risk stratification in suspected CAD/Ischemia, work-up of myocarditis and cardiomyopathies, as well as assessment of viability. CMR imaging is a safe procedure, has diagnostic image quality in more than 98% of cases, and its results have strong impact on patient management. Interim analyses of the specific protocols underscore the prognostic value of clinical routine CMR in CAD and HCM.

Imaging in population science: cardiovascular magnetic resonance in 100,000 participants of UK Biobank - rationale, challenges and approaches

Abstract: UK Biobank is a prospective cohort study with 500,000 participants aged 40 to 69. Recently an enhanced imaging study received funding. Cardiovascular magnetic resonance (CMR) will be part of a multi-organ, multi-modality imaging visit in 3–4 dedicated UK Biobank imaging centres that will acquire and store imaging data from 100,000 participants (subject to successful piloting). In each of UK Biobank’s dedicated bespoke imaging centres, it is proposed that 15–20 participants will undergo a 2 to 3 hour visit per day, seven days a week over a period of 5–6 years. The imaging modalities will include brain MRI at 3 Tesla, CMR and abdominal MRI at 1.5 Tesla, carotid ultrasound and DEXA scans using carefully selected protocols. We reviewed the rationale, challenges and proposed approaches for concise phenotyping using CMR on such a large scale. Here, we discuss the benefits of this imaging study and review existing and planned population based cardiovascular imaging in prospective cohort studies. We will evaluate the CMR protocol, feasibility, process optimisation and costs. Procedures for incidental findings, quality control and data processing and analysis are also presented. As is the case for all other data in the UK Biobank resource, this database of images and related information will be made available through UK Biobank’s Access Procedures to researchers (irrespective of their country of origin and whether they are academic or commercial) for health-related research that is in the public interest.

Gender-specific differences in left ventricular remodelling in obesity: insights from cardiovascular magnetic resonance imaging

Abstract: Aims As obesity-related cardiovascular mortality, although elevated when compared with normal weight, is lower in females than in males at every body mass index (BMI) level, we aimed to investigate gender-specific differences in left ventricular (LV) hypertrophy in obesity, which themselves have been shown to have varying prognostic value. Method and results In total, 741 subjects (female, n = 399) without identifiable cardiovascular risk factors (BMI 15.7–59.2 kg/m2) underwent cardiovascular magnetic resonance (1.5 T) to determine LV mass, end-diastolic volume (EDV, mL), and LV mass/volume ratio (LVM/VR). Across both sexes, there was a strong positive correlation between BMI and LV mass (male r = 0.44, female r = 0.57, both P < 0.001), with males showing a greater LV hypertrophic response (male +2.3 vs. female +1.6 g per BMI point increase, P = 0.001). Concentric hypertrophy was present in both sexes and LVM/VR positively correlated to BMI (male r = 0.45, female r = 0.29, both P < 0.001) on linear regression analysis. However, the degree of concentric hypertrophy was greater in males (male +0.13 vs. female +0.06 LVM/VR increase per BMI point increase, P = 0.001). On the other hand, females showed a greater LV cavity dilatory response (female +1.1 vs. male +0.3 mL per BMI point increase, P < 0.001). Indeed, in contrast to females, where BMI and LV-EDV were positively correlated ( r = 0.38, P < 0.001), BMI did not correlate with EDV in men ( r = 0.03, P = 0.62). Conclusion In the absence of traditional cardiovascular risk factors, obese men show predominantly concentric hypertrophy, whereas obese women exhibit both eccentric and concentric hypertrophy. As concentric hypertrophy is more strongly related to cardiovascular mortality than eccentric hypertrophy, our observations may explain the observed gender difference in obesity-related mortality.

Diagnostic accuracy of cardiac magnetic resonance imaging in the detection and characterization of left atrial catheter ablation lesions: a multicenter experience.

Abstract: This work was funded by the British Heart Foundation (RG/10/11/28457 and Center of Research Excellence Programme) and the National Institute for Health Research as part of Barts and The London NIHR Cardiovascular Biomedical Research Unit and Imperial College Healthcare NHS Trust Biomedical Research Center.

Use of cardiac magnetic resonance and echocardiography in population-based studies: why, where, and when?

Abstract: Population research studies are often directed toward eliciting the association of physiological measurements (eg, left ventricular [LV] function) and clinical variables (eg, hypertension) with outcomes.1 Although cardiovascular magnetic resonance (CMR) is known to be accurate and versatile, until recently, the diffusion of CMR technology was too limited by technical and logistic challenges to consider its use in population studies on a large scale (>10 000). However, with recent technical developments, CMR has reached a level of maturity and ease of use, which makes its use in large-scale population studies a practical reality for the first time. The goal of this review is to facilitate the process of selecting imaging methods for population research studies based on design requirements and existing experience with the techniques. There are 4 fundamental aspects of imaging that are pertinent in population studies: validity, feasibility, accuracy, and reproducibility. ### Validity Selection bias2 is a critical issue in population studies. Inappropriate patient selection may lead to problems in extrapolating sample information even to the population from which the sample was derived, which is a core task of a population-based study. External validity may also be limited by selection. In contrast to this, greater variance in imaging measurements may require larger numbers, as discussed in the later section on accuracy and validity, but may have relatively less importance in population studies than in clinical trials.3 Patient selection is, therefore, critical to external validity. This has been considered carefully in the echocardiographic literature. For example, before the incorporation of 2-dimensional (2D) measurements of LV mass, in addition to M mode, the feasibility of LV mass measurement was somewhat limited, for example, in the Framingham Heart Study and Cardiovascular Health Study. In contrast, more recent studies, such as the Strong Heart Study and Losartan Intervention For Endpoint Reduction in …

A mathematical model of the mechanical link between shortening of the cardiomyocytes and systolic deformation of the left ventricular myocardium

Abstract: BACKGROUND: Left ventricular myocytes are arranged in a complex three-dimensional mesh. Since all myocytes contract approximately to the same degree, mechanisms must exist to enable force transfer from each of these onto the framework as a whole, despite the transmural differences in deformation strain. This process has hitherto not been clarified in detail. OBJECTIVE: To present a geometrical model that establishes a mechanical link between the three-dimensional architecture and the function of the left ventricular myocardium. METHODS: The left ventricular equator was modeled as a cylindrical tube of deformable but incompressible material, composed of virtual cardiomyocytes with known diastolic helical and transmural angles. By imposing reference circumferential, longitudinal, and torsional strains onto the model, we created a three-dimensional deformation field to calculate passive shortening of the myocyte surrogates. We tested two diastolic architectures: 1 a simple model with longitudinal myocyte surrogates in the endo-and epicardium, and circular ones in the midwall, and 2 a more accurate architecture, with progressive helical angle distribution varying from -60° in the epicardium to 60° in the endocardium, with or without torsion and transmural cardiomyocyte angulation. RESULTS: The simple model caused great transmural unevenness in cardiomyocyte shortening; longitudinal surrogates shortened by 15% at all depths equal to the imposed longitudinal strain, whereas circular surrogates exhibited a maximum shortening of 23.0%. The accurate model exhibited a smooth transmural distribution of cardiomyocyte shortening, with a mean range of 17.0 13.2--20.8%. Torsion caused a shortening of 17.0 15.2--18.9% and transmural angulation caused a shortening of 15.2 12.4--18.2%. Combining the effects of transmural angulation and torsion caused a change of 15.2 13.2--16.5%.CONCLUSION: A continuous transmural distribution of the helical angle is obligatory for smooth shortening of the cardiomyocytes, but a combination of torsional and transmural angulation changes is necessary to execute systolic mural thickening whilst keeping shortening of the cardiomyocytes within its physiological range.

Effect of atrial fibrillation ablation on myocardial function: insights from cardiac magnetic resonance feature tracking analysis

Abstract: Restoration of sinus rhythm may result in an improvement of left heart function in patients with atrial fibrillation (AF). Cardiovascular magnetic resonance (CMR) feature tracking (FT) technique may help detect subtle wall-motion abnormalities. Consequently this study aimed to analyse existence and reversibility of subclinical cardiac dysfunction following atrial fibrillation ablation. 28 consecutive patients (mean age 61 years) with paroxysmal AF underwent pulmonary vein isolation. CMR imaging was done 3 (±3) days before and 3.4 (±1.1) months after ablation. Left heart function was determined by performing FT analysis. Statistical analysis included paired student's t test, random effects metaanalysis to assess the cohort's health status and Bland-Altman analysis. 17 patients (61%) were free from AF at follow-up. Bland-Altman analysis showed good coefficients of variation. Of all 195 parameters, 27 changed (14%): 9 improved significantly (5%), 12 worsened significantly (6%), whereas 6 parameters worsened not significantly (3%). 18 of 120 systolic parameters changed (15%), 14 worsened (12%), 4 improved (3%). In 9 of 75 diastolic parameters, values changed (12%): 5 improved (7%) and 4 worsened (5%). Meta-analysis revealed that our collective's FT values at baseline didn't differ significantly from healthy volunteers' values [Q values of 0.01 (p value 0.921) and 1.499 (p value 0.221)]. AF patients undergoing ablation appear to have near normal cardiac wall motion, which does not improve following successful ablation. Feature tracking analysis is a reliable tool to determine treatment effects but is more likely to show positive findings if the population is unhealthy.

CMR and LV noncompaction: does it matter how we measure trabeculations?

Abstract: Left ventricular noncompaction (LVNC) is an intriguing, but poorly understood, condition that can lead to heart failure, malignant arrhythmias, and thromboembolic events It can be associated with neuromuscular disorders and can coexist with other cardiac malformations [(1)][1] Diagnostic imaging

Raised troponin in COPD: clinical implications and possible mechanisms

Abstract: Chronic obstructive pulmonary disease (COPD) is predicted to become the sixth leading cause of disability and the third most common cause of death by 2020. Reduced forced expiratory volume in 1s, a hallmark of COPD, is ranked second to smoking and above blood pressure and cholesterol as a predictor of all-cause and cardiovascular mortality. Even in mild to moderate COPD patients succumb to cardiovascular disease rather than respiratory failure although the causative mechanism is unknown.1 Over the past decade it has become apparent that during an exacerbation of COPD, classically defined by the combination of worsening dyspnoea with increased sputum volume and/or purulence, there is subclinical myocardial damage typified by an increase in troponin level and other biomarkers which predict mortality.2–4 The key question relates to the mechanisms behind this rise, since without an understanding of the mechanisms the ability to identify an appropriate intervention that will improve outcome is hindered. Soyseth and colleagues5 seek to further the understanding of this relationship. Specifically they addressed the important issue as to whether the raised levels of troponin found at exacerbation are chronically raised or are a phenomenon related to the exacerbation itself, and found that the troponin levels were significantly higher in the exacerbator group compared with stable patients. The study compared those patients admitted to hospital for an exacerbation with those from a pulmonary rehabilitation clinic. It is however questionable whether these groups really represent similar populations in …

Quality of reporting in cardiac MRI, CT and SPECT diagnostic accuracy studies: Analysis of the impact of STARD criteria

Abstract: Methods This paper reports on the reporting quality of cardiac computed tomography (CCT), single positron emission computed tomography (SPECT), and cardiac magnetic resonance (CMR) diagnostic accuracy studies in randomly selected groups of 50: ‘CMR 1995-2002’, ‘CMR 20042011’, ‘CCT f 1995-2002’, and ‘CCT 2004-2011’, ‘SPECT 1995-2002’, ‘SPECT 2004-2011’. These 300 studies were read against the 25 STARD criteria (7500 items assessed) and their % adherence determined. Simple and multivariable linear regression models were developed.

Stress myocardial perfusion cardiac magnetic resonance imaging vs. coronary CT angiography in the diagnostic work-up of patients with stable chest pain: comparative effectiveness and costs

Abstract: Author(s): Genders, Tessa S; Petersen, Steffen E; Pugliese, Francesca; Dastidar, Amardeep; Fleischmann, Kirsten E; Nieman, Koen; Hunink, Myriam

Cardiac magnetic resonance myocardial feature tracking: feasibility for use in left ventricular non-compaction

Abstract: Background Cardiac magnetic resonance (CMR) myocardial feature tracking (FT) is emerging as a sensitive and reproducible method for measuring myocardial strain parameters without the need to acquire additional images. Up until now adult CMRFT studies have primarily focussed on the reproducibility of the software,with very few studies addressing disease states beyond ischaemic cardiomyopathy. The aim of this pilot study was to assess the feasibility of cine-images derived quantitative CMR FT strain parameters to differentiate between normal individuals and patients with Left ventricular non-compaction (LVNC). Methods Patients were identified retrospectively from an established clinical CMR database. 8 LVNC patients with negative invasive angiography or stress CMR myocardial perfusion imaging were compared to 21 normal controls. LVNC was defined according to the Petersen criteria,with an end-diastolic ratio of non-compacted to compacted layer (NC/C) >2.3. LV morphological and functional parameters were performed off-line on a dedicated workstation. CMR 4chamber(4CH) and mid-ventricular short axis(SAX) cineimages were analysed in systole(S) and diastole(D) using dedicated FT software(Diogenes MRI,TomTec Imaging Systems,Munich Germany).