Showing papers by "Steffen E. Petersen published in 2012"

Prediction model to estimate presence of coronary artery disease: retrospective pooled analysis of existing cohorts

Abstract: Objectives To develop prediction models that better estimate the pretest probability of coronary artery disease in low prevalence populations. Design Retrospective pooled analysis of individual patient data. Setting 18 hospitals in Europe and the United States. Participants Patients with stable chest pain without evidence for previous coronary artery disease, if they were referred for computed tomography (CT) based coronary angiography or catheter based coronary angiography (indicated as low and high prevalence settings, respectively). Main outcome measures Obstructive coronary artery disease (≥50% diameter stenosis in at least one vessel found on catheter based coronary angiography). Multiple imputation accounted for missing predictors and outcomes, exploiting strong correlation between the two angiography procedures. Predictive models included a basic model (age, sex, symptoms, and setting), clinical model (basic model factors and diabetes, hypertension, dyslipidaemia, and smoking), and extended model (clinical model factors and use of the CT based coronary calcium score). We assessed discrimination (c statistic), calibration, and continuous net reclassification improvement by cross validation for the four largest low prevalence datasets separately and the smaller remaining low prevalence datasets combined. Results We included 5677 patients (3283 men, 2394 women), of whom 1634 had obstructive coronary artery disease found on catheter based coronary angiography. All potential predictors were significantly associated with the presence of disease in univariable and multivariable analyses. The clinical model improved the prediction, compared with the basic model (cross validated c statistic improvement from 0.77 to 0.79, net reclassification improvement 35%); the coronary calcium score in the extended model was a major predictor (0.79 to 0.88, 102%). Calibration for low prevalence datasets was satisfactory. Conclusions Updated prediction models including age, sex, symptoms, and cardiovascular risk factors allow for accurate estimation of the pretest probability of coronary artery disease in low prevalence populations. Addition of coronary calcium scores to the prediction models improves the estimates.

Chronic obstructive pulmonary disease: a modifiable risk factor for cardiovascular disease?

Abstract: Significant cardiac morbidity and mortality exists in patients with COPD. Shared risk factors include age, smoking history and exposure to air pollution and passive smoke. Although the inappropriate under-prescribing of β-blockers contributes, it is now appreciated that the observed cardiac risk is not only due to smoking and conventional cardiovascular risk factors, but also other independent factors. A number of hypotheses exist for the increased cardiovascular morbidity and mortality seen in COPD including inflammation, pulmonary hypertension, lung hyperinflation and shared genetics models. Mounting evidence from large randomised controlled trials suggests that COPD treatment may be cardio-protective. We review the current evidence supporting the aforementioned hypotheses and how their modulation may prevent cardiovascular morbidity and mortality in COPD. The persisting underdiagnosis of COPD may have significant consequences. Further mechanistic studies identifying the onset and impact of individual interventions will develop our understanding of this emerging and highly relevant clinical field.

Computational fluid dynamics simulation of a-v fistulas: from MRI and ultrasound scans to numeric evaluation of hemodynamics.

Abstract: Purpose A-v anastomosis entails dramatic changes in hemodynamic conditions, which may lead to major alterations to the vessels involved; primarily dilatations and devastating stenoses. Wall shear stress is thought to play a key role in the remodeling of the vessels exposed to abnormal levels and oscillating wall shear stress. In this study we sought to develop a framework suitable for thorough in vivo analyses of wall shear stress and vessel morphology of a-v fistulas in patients. Methods Using ultrasound and magnetic resonance imaging (MRI) transverse image stacks from six patient a-v fistulas were obtained. From the image stacks three-dimensional geometries of the patient fistulas were created using dedicated segmentation software. Geometries of three a-v fistulas were imported into finite element software in order to perform fluid flow simulations of blood flows and frictional forces on the vessel walls in the a-v fistulas. Boundary conditions for the simulations were obtained using both a MRI phase contrast and an ultrasound Doppler technique. Results The segmentation of the six fistulas of very different age and morphology (two end-to-side and four side-to-side) showed the ability of the approach to create geometries of various fistula morphologies. Simulations of the three fistulas showed an instant picture of the present status of the exposure to different levels of wall shear stress and the morphological status in the vessel remodeling process. Conclusion The study demonstrated the capability of the CFD framework to analyze patient a-v fistulas on a regular basis using both MRI and ultrasound-based approaches.

CMR right ventricular strain assessment using feature tracking cine images: agreement with echocardiography

Abstract: Right ventricular strain assessment by feature tracking from cine images shows acceptable levels of agreement with echocardiography

Cardiovascular changes in patients with acromegaly assessed by CMR

Abstract: Summary The study describes cardiovascular changes in patients with acromegaly before and one year after treatment. Background Acromegaly causes a distinct cardiomyopathy, which remains poorly understood, because cardiac changes typically appear before the development of hypertension or diabetes. The aim of the study was to describe cardiovascular changes in patients with acromegaly before and one year after treatment. Methods Thirteen patients with acromegaly and age- and sexmatched controls (n=13) underwent CMR. Patients underwent scans before disease treatment and at twelve months after treatment. Cardiac parameters were calculated and indexed to body surface area (BSA). The comparison between groups was done using Mann-UWhitney test and within the group using Wilcoxon test. Results In patients with acromegaly left ventricular (LV) mass index (LVMi) was increased (65.7 vs. 45.8 g/m2, p=0.0021) and was observed in both females (58.8 v. 40.9 g/m2, p=0.0028) and males (71.1 vs. 56.7 g/m2, p=0.0286) compared to matched controls. The LVMi did not correlate with the serum insulin growth factor (IGF) activity (r=0.099, p=0.745) or age (r=-0.08, p=0.175). Patients with acromegaly had significantly higher cardiac index (CI; 3.7 vs. 3.0 l/min/m2, p=0.021) However, there were no differences between end diastolic volume index (EDVi; 86.9 vs. 75.4 ml/m2, p=0.0649), end systolic volume index (ESVi; 35.1 vs. 29.3 ml/m2, p=0.1662) and ejection fraction (EF; 60 vs. 59 %, p=0.327) in acromegaly group and controls. There were no differences between right ventricular (RV) RVEDVi (81.3 vs. 72.5 ml/m2, p=0.2382), RVESVi (32.7 vs. 29.1, p=0.6816) and RVEF (61 vs. 59 %, p=0.4407) in the acromegaly group and controls. At one year, patients with acromegaly demonstrated a significant fall in IGF with treatment (with somatostatin analogues or transphenoidal surgery) from baseline median IGF-I SDS +10.58 (range 1.19 to 6.52) to +0.40 (range -1.93 to 3.02) at one year (p=0.0042). CMR parameters of the LV did not change after 1 year of therapy: LVMi 65.7 vs. 61.0 g/m2, p=0.0547; EDVi 89.5 vs. 85.8 ml/m2, p=0.1641; ESVi 33.7 vs. 30.1 ml/m2, p=0.6523; EF 60 vs. 66 %, p=0.7792; CI 3.7 vs. 3.4 l/min/m2, p=0.4961.

Is there a role for stress CMR in stable chest pain with >60% predicted risk of coronary artery disease?

Abstract: Sir, The 2010 NICE guidelines1 on stable chest pain of recent origin have revolutionized its management. The management strategy is based on the estimated likelihood of coronary artery disease (CAD) using age, sex, risk factors and the character of chest pain. Functional imaging (for e.g. stress CMR/stress echo/myocardial perfusion scintigraphy) is only recommended in the group with predicted risk between 30% and 60%. The recently published CE-MARC study2 has shown that stress CMR is superior to SPECT in assessment of stable chest pain. In the CE-MARC study the overall X-ray angiography …

Effect of mechanical brushing on survival and hemodynamic characteristics of tunneled hemodialysis catheters

Abstract: PurposeTunneled catheters used for hemodialysis treatment often become dysfunctional due to deposition of clotting material within the catheter lumen. In a retrospective study design we investigated the effect of mechanical brushing of dysfunctional tunneled catheters using a metal guide wire with simultaneous installation of urokinase.Materials and MethodsDuring a period of 26 months all together 24 different catheters in 21 chronic hemodialysis patients were brushed due to insufficient blood flow or increased arterial or venous line pressures resulting in repeated alarms during dialysis treatments.ResultsMedian functional survival after brushing was 45 days with 8 catheters being exchanged (n=5) or rebrushed (n=3) within 10 dialysis sessions (4 weeks). After 2 months all together 13 (54%) catheters were exchanged due to repeated dysfunction and by 3 months functional survival was only about 35%. The catheters needing exchange were characterized by low flow and high arterial line resistance already in th...

Gender specific differences in left ventricular remodelling in obesity may explain differences in obesity related mortality

Abstract: Summary Across both genders, obesity, in the absence of traditional cardiovascular risk factors, is characterized by concentric LV remodeling. Whereas males show predominantly concentric remodeling, females exhibit eccentric and concentric hypertrophy. This may explain the observed gender difference in obesity related cardiovascular mortality. Background Obesity related cardiovascular mortality, although elevated when compared to normal weight, is lower in females (♀ )t han males ( ♂ )a t every body mass index (BMI) level. Given the fact that males have less fat tissue than females at each BMI level, the reasons behind this trend are unlikely to be attributable to the effects of excess adiposity alone. As different patterns of left ventricular (LV) remodeling have been shown to have varying prognostic value, with concentric hypertrophy being more strongly predictive of cardiovascular mortality than eccentric hypertrophy, our aim was to investigate whether sex-specific differences in LV remodeling could provide an additional explanation for the observed gender difference in obesity related mortality. Methods 703 subjects (♀ n= 390, ♂ n=313) without identifiable cardiovascular risk factors, (BMI range 15.7-59.2 Kg/ M2) underwent cardiovascular magnetic resonance at 1.5 Tesla for the assessment of LV mass (g), enddiastolic volume (EDV; ml) and LV mass/volume ratio (LVM/VR).