Heinz Pfluger

Evaluation of diffuse myocardial fibrosis in heart failure with cardiac magnetic resonance contrast-enhanced T1 mapping.

OBJECTIVES The purpose of this study was to investigate a noninvasive method for quantifying diffuse myocardial fibrosis with cardiac magnetic resonance imaging (CMRI). BACKGROUND Diffuse myocardial fibrosis is a fundamental process in pathologic remodeling in cardiomyopathy and is postulated to cause increased cardiac stiffness and poor clinical outcomes. Although regional fibrosis is easily imaged with cardiac magnetic resonance, there is currently no noninvasive method for quantifying diffuse myocardial fibrosis. METHODS We performed CMRI on 45 subjects (25 patients with heart failure, 20 control patients), on a clinical 1.5-T CMRI scanner. A prototype T(1) mapping sequence was used to calculate the post-contrast myocardial T(1) time as an index of diffuse fibrosis; regional fibrosis was identified by delayed contrast enhancement. Regional and global systolic function was assessed by cine CMRI in standard short- and long-axis planes, with echocardiography used to evaluate diastology. An additional 9 subjects underwent CMRI and endomyocardial biopsy for histologic correlation. RESULTS Post-contrast myocardial T(1) times correlated histologically with fibrosis (R = -0.7, p = 0.03) and were shorter in heart failure subjects than controls (383 +/- 17 ms vs. 564 +/- 23 ms, p < 0.0001). The T(1) time of heart failure myocardium was shorter than that in controls even when excluding areas of regional fibrosis (429 +/- 22 ms vs. 564 +/- 23 ms, p < 0.0001). The post-contrast myocardial T(1) time shortened as diastolic function worsened (562 +/- 24 ms in normal diastolic function vs. 423 +/- 33 ms in impaired diastolic function vs. 368 +/- 20 ms in restrictive function, p < 0.001). CONCLUSIONS Contrast-enhanced CMRI T(1) mapping identifies changes in myocardial T(1) times in heart failure, which appear to reflect diffuse fibrosis.

Myocardial Fibrosis Predicts Appropriate Device Therapy in Patients With Implantable Cardioverter-Defibrillators for Primary Prevention of Sudden Cardiac Death

OBJECTIVES The purpose of this study was to evaluate the association between regional myocardial fibrosis and ventricular arrhythmias in patients with cardiomyopathy. BACKGROUND Patients with heart failure are at risk of sudden cardiac death (SCD). Current guidelines recommend implantable cardioverter-defibrillator (ICD) devices for a subgroup based on impaired left ventricular function. A significant proportion of devices never discharge, hence a more accurate method for targeting those at risk is desirable. METHODS We prospectively enrolled 103 patients meeting criteria for ICD implantation for primary prevention of SCD. Cardiac magnetic resonance imaging was performed before device implantation. Regional fibrosis was identified with late gadolinium enhancement (LGE). RESULTS Median follow-up was 573 days (interquartile range: 379 to 863 days). The LGE identified regional fibrosis in 31 of 61 (51%) patients with nonischemic cardiomyopathy (NICM) and in all 42 patients with ischemic cardiomyopathy (ICM). There was a 29% (9 of 31) discharge rate in the NICM group with LGE compared with a 14% (6 of 42) discharge rate in the ICM group (p = NS). There were no ICD discharges in the NICM group without LGE, which was significantly lower than the rate observed in both the ICM patients (p = 0.04) and the NICM patients with LGE (p < 0.01). Left ventricular ejection fraction was similar in patients with and without device therapy (24 ± 12% vs. 26 ± 8%, p = NS) and those with or without LGE (25 ± 9% vs. 26 ± 9%, p = NS). CONCLUSIONS Patients with advanced cardiomyopathy and myocardial fibrosis demonstrated by LGE on cardiac magnetic resonance imaging have a high likelihood of appropriate ICD therapy. Correspondingly, absence of LGE may indicate a lower risk for malignant ventricular arrhythmias.

Disproportionate Exercise Load and Remodeling of the Athlete's Right Ventricle

PURPOSE There is evolving evidence that intense exercise may place a disproportionate load on the right ventricle (RV) when compared with the left ventricle (LV) of the heart. Using a novel method of estimating end-systolic wall stress (ES-σ), we compared the RV and LV during exercise and assessed whether this influenced chronic ventricular remodeling in athletes. METHODS For this study, 39 endurance athletes (EA) and 14 nonathletes (NA) underwent resting cardiac magnetic resonance (CMR), maximal oxygen uptake (VO2), and exercise echocardiography studies. LV and RV end-systolic wall stress (ES-σ) were calculated using the Laplace relation (ES-σ = Pr/(2h)). Ventricular size and wall thickness were determined by CMR; invasive and Doppler echo estimates were used to measure systemic and pulmonary ventricular pressures, respectively; and stroke volume was quantified by Doppler echocardiography and used to calculate changes in ventricular geometry during exercise. RESULTS In EA, compared with NA, resting CMR measures showed greater RV than LV remodeling. The ratios RV ESV/LV ESV (1.40 ± 0.23 vs 1.26 ± 0.12, P = 0.007) and RV mass/LV mass (0.29 ± 0.04 vs 0.25 ± 0.03, P = 0.012) were greater in EA than in NA. RVES-σ was lower at rest than LVES-σ (143 ± 44 vs 252 ± 49 kdyn · cm, P < 0.001) but increased more with strenuous exercise (125% vs 14%, P < 0.001), resulting in similar peak exercise ES-σ (321 ± 106 vs 286 ± 77 kdyn · cm, P = 0.058). Peak exercise RVES-σ was greater in EA than in NA (340 ± 107 vs 266 ± 82 kdyn · cm, P = 0.028), whereas RVES-σ at matched absolute workloads did not differ (P = 0.79). CONCLUSIONS Exercise induces a relative increase in RVES-σ which exceeds LVES-σ. In athletes, greater RV enlargement and greater wall thickening may be a product of this disproportionate load excess.

Diagnostic performance of multisequential cardiac magnetic resonance imaging in acute cardiac allograft rejection

We evaluated cardiac magnetic resonance imaging (CMR) as a non‐invasive test for cardiac allograft rejection.

Combined dyssynchrony and scar imaging with cardiac magnetic resonance imaging predicts clinical response and long-term prognosis following cardiac resynchronization therapy.

AIMS Cardiac resynchronization therapy (CRT) is advocated in advanced heart failure; however, patient selection remains challenging. We examined the utility of multi-sequential cardiac magnetic resonance imaging (CMR) in predicting outcome after CRT. METHODS AND RESULTS We performed multi-sequential CMR on 40 subjects with cardiomyopathy and advanced heart failure, despite optimized medical therapy. All patients had been recommended for CRT according to accepted clinical guidelines. Patients were defined by CMR as likely responders if they had significant mechanical dyssynchrony (> or =65 ms delay between septal and posterolateral wall contraction on cine imaging), and no transmural scarring of the anteroseptal or posterolateral wall on delayed contrast-enhanced imaging. Clinical composite score was recorded at baseline and 6 months post-CRT. Long-term follow-up (transplant-free survival) was 497 +/- 55 days post-CRT. A clinical response was achieved in 19/26 (73%) of the CMR-predicted responders and 2/12 (17%) of the CMR-predicted non-responders (P < 0.01, chi(2)). The sensitivity of CMR for prediction of clinical response to CRT was 90%, with a specificity of 59%. Transplant-free survival post-CRT was achieved in 88% of the CMR-predicted responders and 58% of the CMR-predicted non-responders (P < 0.05, Kaplan-Meier survival analysis). CONCLUSION Multi-sequential CMR identifies patients with severe cardiomyopathy who will respond to CRT with a favourable long-term prognosis.

Utility of Myocardial Fibrosis and Fatty Infiltration Detected by Cardiac Magnetic Resonance Imaging in the Diagnosis of Arrhythmogenic Right Ventricular Dysplasia—A Single Centre Experience

INTRODUCTION Cardiac magnetic resonance imaging (CMR) has evolved as a major diagnostic tool to evaluate arrhythmogenic right ventricular dysplasia (ARVD). However, there is a lack of consensus in the interpretation of findings such as fatty infiltration or myocardial fibrosis. We examined the diagnostic utility of these two features in the diagnosis of ARVD. METHODS We performed fast imaging employing steady-state acquisition cine imaging, T(1)-weighted black blood imaging with and without fat suppression and post-contrast delayed enhancement on a 1.5-T scanner to evaluate ventricular function and morphology, fatty infiltration and regional myocardial fibrosis in 52 subjects with suspected ARVD. RESULTS Eight subjects met the international diagnostic criteria for ARVD. Right ventricle (RV) delayed hyper-enhancement was found in 7 of 8 (88%) ARVD subjects compared to 6 of 44 (14%) subjects without ARVD (p<0.001). Fatty infiltration was only identified in 1 ARVD patient, and 1 non-ARVD patient. On multiple logistic regression analysis RV enhancement remained an independent predictor for the diagnosis of ARVD (p<0.05). CONCLUSION RV delayed enhancement is common in patients with ARVD, whereas detection of fatty infiltration of the right ventricle was rare in our patient population. The inclusion of RV fibrosis on CMR as a feature of ARVD may improve the diagnostic accuracy of this condition.

One- and Two-dimensional Estimation of Right and Left Ventricular Size and Function—Comparison with Cardiac Magnetic Resonance Imaging Volumetric Analysis

BACKGROUND Estimations of right ventricular (RV) and left ventricular (LV) size and function based on 1D and 2D measures are commonly used. However, their correlation with volumetric analysis methods is not well documented. METHODS We analysed a series of subjects undergoing CMR (n=30). Contiguous short axis cine imaging was obtained to assess RV and LV volumes and function. Standard short and long axis cine imaging were performed to evaluate linear and planimetric dimensions as well as functional analysis. RESULTS Linear and planimetric measurements of the RV in standard long and short axis views correlated weakly with standard volumetric measurements (r=0.34-0.73). RV ejection fraction (EF), when calculated from single plane functional analysis correlated only moderately with the volumetric EF (r=0.75, p<0.001). In contrast, estimation of LV volumes, mass and EF by biplane area-length method demonstrated excellent correlation with volumetric data (r=0.89, 0.92 and 0.91, p<0.001 for all). CONCLUSION Two-dimensional estimations of volume and function correlate well with LV volumetric analysis, but not with RV volumetric analysis. Estimation of RV size and function based on linear or planimetric assumption models should be performed and interpreted with caution.