[Show abstract][Hide abstract] ABSTRACT: Microvascular dysfunction in HCM has been associated with adverse clinical outcomes. Advances in quantitative cardiovascular magnetic resonance (CMR) perfusion imaging now allow myocardial blood flow to be quantified at the pixel level. We applied these techniques to investigate the spectrum of microvascular dysfunction in hypertrophic cardiomyopathy (HCM) and to explore its relationship with fibrosis and wall thickness.
Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance. 08/2014; 16(1):49.
[Show abstract][Hide abstract] ABSTRACT: Myocardial fibrosis identified by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in patients with hypertrophic cardiomyopathy (HCM) is associated with adverse cardiovascular events, but its value as an independent risk factor for sudden cardiac death (SCD) is unknown. We investigated the role of LGE-CMR in the risk stratification of HCM.
[Show abstract][Hide abstract] ABSTRACT: Anabolic steroid (AS) misuse is widespread amongst recreational bodybuilders; however, their effects on the cardiovascular system are uncertain. Our aim was to document the impact of AS use on cardiac structure, function and the presence of focal fibrosis using the gold standard cardiovascular magnetic resonance imaging (CMR).
A cross-sectional cohort design was utilised with 21 strength-trained participants who underwent CMR imaging of the heart and speckle-tracking echocardiography. Thirteen participants (30 ± 5 years) taking AS for at least 2 years and currently on a "using"-cycle were compared with age and training-matched controls (n = 8; 29 ± 6 years) who self-reported never having taken AS (NAS).
AS users had higher absolute left ventricular (LV) mass (220 ± 45 g) compared to NAS (163 ± 27 g; p < 0.05) but this difference was removed when indexed to fat-free mass. AS had a reduced right ventricular (RV) ejection fraction (AS 51 ± 4 % vs. NAS 59 ± 5 %; p < 0.05) and a significantly lower left ventricular E':A' myocardial tissue velocity ratio [AS 0.99(0.54) vs. NAS 1.78(0.46) p < 0.05] predominantly due to greater tissue velocities with atrial contraction. Peak LV longitudinal strain was lower in AS users (AS -14.2 ± 2.7 % vs. NAS -16.6 ± 1.9 %; p < 0.05). There was no evidence of focal fibrosis in any participant.
AS use was associated with significant LV hypertrophy, albeit in-line with greater fat-free mass, reduced LV strain, diastolic function, and reduced RV ejection fraction in male bodybuilders. There was, however, no evidence of focal fibrosis in any AS user.
[Show abstract][Hide abstract] ABSTRACT: Cardiac diffusion tensor imaging (cDTI) measures the magnitudes and directions of intramyocardial water diffusion. Assuming the cross-myocyte components to be constrained by the laminar microstructures of myocardium, we hypothesized that cDTI at two cardiac phases might identify any abnormalities of laminar orientation and mobility in hypertrophic cardiomyopathy (HCM).
Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance. 01/2014; 16:87.
[Show abstract][Hide abstract] ABSTRACT: Cardiovascular Magnetic Resonance (CMR) is the gold-standard technique for assessment of ventricular function. Although left ventricular (LV) volumes and ejection fraction are strong predictors of outcome in dilated cardiomyopathy (DCM), there are limited data regarding the prognostic significance of right ventricular (RV) systolic dysfunction (RVSD). We investigated whether CMR assessment of RV function has prognostic value in DCM.
We prospectively studied 250 consecutive DCM patients using CMR. RVSD, defined by RV ejection fraction ≤45%, was present in 86 (34%) patients. During a median follow-up period of 6.8 years, there were 52 deaths and 7 patients underwent cardiac transplantation . The primary end point of all-cause mortality or cardiac transplantation was reached by 42 of 86 patients with RVSD and 17 of 164 patients without RVSD (49% vs. 10%; hazard ratio [HR], 5.90; 95% confidence interval [CI], 3.35 to 10.37; P<0.001). On multivariable analysis, RVSD remained a significant independent predictor of the primary end point (HR, 3.90; 95% CI, 2.16 to 7.04; P<0.001), as well as secondary outcomes of cardiovascular mortality or cardiac transplantation (HR, 3.35; 95% CI, 1.76 to 6.39; P<0.001), and heart failure (HF) death, HF hospitalization or cardiac transplantation (HR, 2.70; 95% CI, 1.32 to 5.51; P=0.006). Assessment of RVSD improved risk stratification for all-cause mortality or cardiac transplantation (net reclassification improvement, 0.31; 95% CI 0.10 to 0.53; P=0.001).
RVSD is a powerful, independent predictor of transplant-free survival and adverse HF outcomes in DCM. CMR assessment of RV function is important in the evaluation and risk stratification of DCM patients.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Early recognition and accurate risk stratification are important in the management of arrhythmogenic right ventricular cardiomyopathy (ARVC). Identification of predictors of outcome by cardiovascular magnetic resonance (CMR) in patients undergoing evaluation for ARVC is limited. We investigated the predictive value of morphological abnormalities detected by CMR for major clinical events in patients with suspected ARVC. METHODS: We performed a longitudinal study on 369 consecutive patients with at least one criterion for ARVC. Abnormal CMR was defined by the presence of one of the following: increased right ventricular (RV) volumes, reduced RV ejection fraction, RV regional wall motion abnormalities, myocardial fatty infiltration, and myocardial fibrosis. The end-point was a composite of cardiac death, sustained ventricular tachycardia, ventricular fibrillation, and appropriate ICD discharge. RESULTS: Twenty patients met the composite end-point over a mean follow-up of 4.3±1.5years. An abnormal CMR was an independent predictor of outcomes (p<0.001). The presence of multiple abnormalities heralded a particular high risk of events (HR 23.0, 95% CI 5.7-93.2, p<0.001 for 2 abnormalities; HR 35.8, 95% CI 9.7-132.6, p<0.001 for 3 or more abnormalities). The positive predictive value of an abnormal CMR study was 21.0% for an adverse event, whilst the negative predictive value of a normal CMR study was 98.8% over the follow-up period. CONCLUSIONS: CMR provides important prognostic information in patients under evaluation for ARVC. A normal study portends a good prognosis. Conversely, the presence of multiple abnormalities identifies a high risk group of patients who may benefit from ICD implantation.
International journal of cardiology 05/2013; · 6.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A healthy average HA map was synthesised from a dataset of 10 healthy volunteers, matching the myocardial shape of the DTI data being analysed. This map allows for a direct pixel-by-pixel comparison of the cardiac fibres’ orientation in vivo. This technique was subsequently applied to evaluate the improved accuracy of in vivo cardiac DTI data sets based on numbers of averages, together with mean diffusivity and fractional anisotropy quantitation.
ISMRM Annual Meeting & Exhibition, Salt Lake City, Utah, USA; 04/2013
[Show abstract][Hide abstract] ABSTRACT: Zonal-excitation and partial-Fourier were combined to speed up a diffusion-weighted stimulated-echo single-shot-EPI technique to acquire in-vivo cardiac Diffusion Tensor Imaging (cDTI) at any time point over the entire cardiac cycle. 5 healthy volunteers were scanned. Mean-diffusivity, fractional-anisotropy, helix-angle and superquadric glyph maps were produced. We show here for the first time in-vivo cDTI images of the human heart over the entire cardiac cycle. The rotation of the diffusion tensor as the heart contracts and expands can be observed. This technique promises to provide novel insights into the structure-function relationships in the heart, and its changes in the presence of disease.
ISMRM Annual Meeting & Exhibition, Salt Lake City, Utah, USA; 04/2013
[Show abstract][Hide abstract] ABSTRACT: AIMS: Echocardiographic studies have shown that left atrial volume (LAV) predicts adverse outcome in small heart failure (HF) cohorts of mixed aetiology. However, the prognostic value of LAV in non-ischaemic dilated cardiomyopathy (DCM) is unknown. Cardiovascular magnetic resonance (CMR) allows accurate and reproducible measurement of LAV. We sought to determine the long-term prognostic significance of LAV assessed by CMR in DCM. METHODS AND RESULTS: We measured LAV indexed to body surface area (LAVi) in 483 consecutive DCM patients referred for CMR. Patients were prospectively followed up for a primary endpoint of all-cause mortality or cardiac transplantation. During a median follow-up of 5.3 years, 75 patients died and 9 underwent cardiac transplantation. After adjustment for established risk factors, LAVi was an independent predictor of the primary endpoint [hazard ratio (HR) per 10 mL/m2 1.08; 95% confidence interval (CI) 1.01-1.15; P = 0.022]. LAVi was also independently associated with the secondary composite endpoints of cardiovascular mortality or cardiac transplantation (HR per 10 mL/m2 1.11; 95% CI 1.04-1.19; P = 0.003), and HF death, HF hospitalization, or cardiac transplantation (HR per 10 mL/m2 1.11; 95% CI 1.04-1.18; P = 0.001). The optimal LAVi cut-off value for predicting the primary endpoint was 72 mL/m2. Patients with LAVi >72 mL/m2 had a three-fold elevated risk of death or transplantation (HR 3.00; 95% CI 1.92-4.70; P < 0.001). LAVi provided incremental prognostic value for the prediction of transplant-free survival (net reclassification improvement 0.17; 95% CI 0.05-0.29; P = 0.002). CONCLUSIONS: LAVi is a powerful independent predictor of transplant-free survival and HF outcomes in DCM. Assessment of LAV improves risk stratification in DCM and should be incorporated into routine CMR examination.
European Journal of Heart Failure 03/2013; · 5.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Risk stratification of patients with nonischemic dilated cardiomyopathy is primarily based on left ventricular ejection fraction (LVEF). Superior prognostic factors may improve patient selection for implantable cardioverter-defibrillators (ICDs) and other management decisions.
To determine whether myocardial fibrosis (detected by late gadolinium enhancement cardiovascular magnetic resonance [LGE-CMR] imaging) is an independent and incremental predictor of mortality and sudden cardiac death (SCD) in dilated cardiomyopathy.
Prospective, longitudinal study of 472 patients with dilated cardiomyopathy referred to a UK center for CMR imaging between November 2000 and December 2008 after presence and extent of midwall replacement fibrosis were determined. Patients were followed up through December 2011.
Primary end point was all-cause mortality. Secondary end points included cardiovascular mortality or cardiac transplantation; an arrhythmic composite of SCD or aborted SCD (appropriate ICD shock, nonfatal ventricular fibrillation, or sustained ventricular tachycardia); and a composite of HF death, HF hospitalization, or cardiac transplantation.
Among the 142 patients with midwall fibrosis, there were 38 deaths (26.8%) vs 35 deaths (10.6%) among the 330 patients without fibrosis (hazard ratio [HR], 2.96 [95% CI, 1.87-4.69]; absolute risk difference, 16.2% [95% CI, 8.2%-24.2%]; P < .001) during a median follow-up of 5.3 years (2557 patient-years of follow-up). The arrhythmic composite was reached by 42 patients with fibrosis (29.6%) and 23 patients without fibrosis (7.0%) (HR, 5.24 [95% CI, 3.15-8.72]; absolute risk difference, 22.6% [95% CI, 14.6%-30.6%]; P < .001). After adjustment for LVEF and other conventional prognostic factors, both the presence of fibrosis (HR, 2.43 [95% CI, 1.50-3.92]; P < .001) and the extent (HR, 1.11 [95% CI, 1.06-1.16]; P < .001) were independently and incrementally associated with all-cause mortality. Fibrosis was also independently associated with cardiovascular mortality or cardiac transplantation (by fibrosis presence: HR, 3.22 [95% CI, 1.95-5.31], P < .001; and by fibrosis extent: HR, 1.15 [95% CI, 1.10-1.20], P < .001), SCD or aborted SCD (by fibrosis presence: HR, 4.61 [95% CI, 2.75-7.74], P < .001; and by fibrosis extent: HR, 1.10 [95% CI, 1.05-1.16], P < .001), and the HF composite (by fibrosis presence: HR, 1.62 [95% CI, 1.00-2.61], P = .049; and by fibrosis extent: HR, 1.08 [95% CI, 1.04-1.13], P < .001). Addition of fibrosis to LVEF significantly improved risk reclassification for all-cause mortality and the SCD composite (net reclassification improvement: 0.26 [95% CI, 0.11-0.41]; P = .001 and 0.29 [95% CI, 0.11-0.48]; P = .002, respectively).
Assessment of midwall fibrosis with LGE-CMR imaging provided independent prognostic information beyond LVEF in patients with nonischemic dilated cardiomyopathy. The role of LGE-CMR in the risk stratification of dilated cardiomyopathy requires further investigation.
JAMA The Journal of the American Medical Association 03/2013; 309(9):896-908. · 29.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Myocardial disarray is an important histological feature of hypertrophic cardiomyopathy (HCM) which has been studied post-mortem, but its in-vivo prevalence and extent is unknown. Cardiac Diffusion Tensor Imaging (cDTI) provides information on mean intravoxel myocyte orientation and potentially myocardial disarray. Recent technical advances have improved in-vivo cDTI, and the aim of this study was to assess the interstudy reproducibility of quantitative in-vivo cDTI in patients with HCM. Methods and results A stimulated-echo single-shot-EPI sequence with zonal excitation and parallel imaging was implemented. Ten patients with HCM were each scanned on 2 different days. For each scan 3 short axis mid-ventricular slices were acquired with cDTI at end systole. Fractional anisotropy (FA), mean diffusivity (MD), and helix angle (HA) maps were created using a cDTI post-processing platform developed in-house. The mean +/- SD global FA was 0.613 +/-0.044, MD was 0.750 +/-0.154 x 10-3 mm2/s and HA was epicardium 34.3 +/-7.6degrees, mesocardium 3.5 +/-6.9degrees and endocardium 38.9 +/-8.1degrees. Comparison of initial and repeat studies showed global interstudy reproducibility for FA (SD = +/-0.045, Coefficient of Variation (CoV) = 7.2%), MD (SD = +/-0.135 x 10-3 mm2/s, CoV = 18.6%) and HA (epicardium SD = +/-4.8degrees; mesocardium SD = +/-3.4degrees; endocardium SD = +/-2.9degrees). Reproducibility of FA was superior to MD (p = 0.003). Global MD was significantly higher in the septum than the reference lateral wall (0.784 +/-0.188 vs 0.750 +/-0.154 x10-3 mm2/s, p < 0.001). Septal HA was significantly lower than the reference lateral wall in all 3 transmural layers (from 8.3degrees to 10.4degrees, all p < 0.001). CONCLUSIONS: To the best of our knowledge, this is the first study to assess the interstudy reproducibility of DTI in the human HCM heart in-vivo and the largest cDTI study in HCM to date. Our results show good reproducibility of FA, MD and HA which indicates that current technology yields robust in-vivo measurements that have potential clinical value. The interpretation of regional differences in the septum requires further investigation.
Journal of Cardiovascular Magnetic Resonance 12/2012; 14(1):86. · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: While the utilization of integrated backscatter intravascular ultrasound (IB-IVUS) for the quantitative in vivo assessment of coronary plaque continues to grow, the validity of IB-IVUS images obtained from newly developed and conventional systems remains uncertain.
To assess the accuracy and reliability of a newly developed IB-IVUS system (VISIWAVE) as compared to the conventional system (Clearview), we compared quantitative IB-IVUS plaque characteristics in the 2 systems using 125 post-mortem specimens from 26 coronary arteries in 11 cadavers, as well as using 200 clinical plaques in 32 patients undergoing coronary intervention. The overall agreement between the histological and IB-IVUS diagnoses using VISIWAVE (Cohen's κ=0.82, 95%CI: 0.73-0.90) was similar to that using Clearview (Cohen's κ=0.80, 95%CI: 0.71-0.89). The 2 systems also demonstrated comparably high sensitivity and specificity. In the direct comparison, the overall agreement between IB-IVUS diagnoses using VISIWAVE and Clearview was also excellent (Cohen's κ=0.87, 95%CI: 0.78-0.95). In the clinical comparison, measured plaque dimensions were similar (VISIWAVE: 8.27±3.46 mm(2) vs. Clearview; 8.31±3.46 mm(2), P=0.44) and there was strong concordance between both greyscale and IB-IVUS parameters.
There was close agreement of analyzed results in both systems when compared with the gold standard of histology. Both systems are able to reliably and accurately characterize coronary plaque and thereby make a valuable contribution to our understanding of atherosclerosis.