Progression of Myocardial Fibrosis in Hypertrophic Cardiomyopathy: A Cardiac Magnetic Resonance Study

Abstract

Objectives: This study examined fibrosis progression in hypertrophic cardiomyopathy (HCM) patients, as well as its relationship to patient characteristics, clinical outcomes, and its effect on clinical decision making.

Background: Myocardial fibrosis, as quantified by late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR), provides valuable prognostic information in patients with HCM.

Methods: A total of 157 patients with HCM were enrolled in this study, with 2 sequential CMR scans separated by an interval of 4.7 ± 1.9 years.

Results: At the first CMR session (CMR-1), 70% of patients had LGE compared with 85% at CMR-2 (p = 0.001). The extent of LGE extent increased between the 2 CMR procedures, from 4.0 ± 5.6% to 6.3 ± 7.4% (p < 0.0001), with an average LGE progression rate of 0.5 ± 1.0%/year. LGE mass progression was correlated with higher LGE mass and extent on CMR-1 (p = 0.0017 and p = 0.007, respectively), greater indexed left ventricular (LV) mass (p < 0.0001), greater LV maximal wall thickness (p < 0.0001), apical aneurysm at CMR-1 (p < 0.0001), and lower LV ejection fraction (EF) (p = 0.029). Patients who were more likely to have a higher rate of LGE progression presented with more severe disease at baseline, characterized by LGE extent >8% of LV mass, indexed LV mass >100 g/m², maximal wall thickness ≥20 mm, LVEF ≤60%, and apical aneurysm. There was a significant correlation between the magnitude of LGE progression and future implantation of insertable cardioverter-defibrillators (p = 0.004), EF deterioration to ≤50% (p < 0.0001), and admission for heart failure (p = 0.0006).

Conclusions: Myocardial fibrosis in patients with HCM is a slowly progressive process. Progression of LGE is significantly correlated with a number of clinical outcomes such as progression to EF ≤50% and heart failure admission. Judicious use of serial CMR with LGE can provide valuable information to help patient management.

Keywords: cardiac magnetic resonance; hypertrophic cardiomyopathy; late gadolinium enhancement.