Longitudinal changes of myocardial fibrosis in hypertrophic cardiomyopathy revealed by cardiac magnetic resonance

Abstract

Objectives: This study was conducted in hypertrophic cardiomyopathy (HCM) 1) to evaluate whether, in HCM, late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is a progressive phenomenon

and 2) to determine the factors predicting its changes over time. Background: Although LGE can reflect myocardial fibrosis in HCM, there is a paucity of data available on its progression. Methods: A total of 61 HCM patients (59±14 years

41 males) were prospectively enrolled. Two consecutive CMR scans were performed on each patient with a time interval of 570±175 days. The LGE extent was quantified as a proportion of total left ventricular (LV) myocardium (%LGE). Results: LGE was present in 57 patients (93.4%) at the 1st CMR. In all, LGE extent was significantly increased over the period between the 2 CMR scans (6.8±6.4% vs. 9.0±8.8%, p<0.001). LGE progression, defined as >4% increase in LGE at the 2nd CMR, was present in 15 patients with non-apical HCM (24.6%), but in none of the patients with apical HCM. A higher %LGE at the 1st CMR and HCM phenotype were two important predictors for LGE progression (p<0.001 and p=0.006, respectively). A difference in %LGE was correlated with the initial %LGE (r=0.46, p<0.001). LGE progression rate was significantly higher in non-apical (0.16%/month) vs. apical HCM (0.025%/month) (p=0.002). On ROC curve analysis, sensitivity and specificity for prediction of LGE progression were 93% and 84%, respectively, with %LGE at the 1st CMR of 7.7% as the best cutoff (p<0.001). Conclusions: Myocardial fibrosis in HCM is a rapid and progressive phenomenon in non-apical HCM. Initial LGE extent is a key predictor for LGE progression, while apical HCM plays a protective role.