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

ObjectivesThis 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.BackgroundMyocardial fibrosis, as quantified by late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR), provides valuable prognostic information in patients with HCM.MethodsA 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.ResultsAt 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).ConclusionsMyocardial 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.