Myocardial fibrosis progression on cardiac magnetic resonance in hypertrophic cardiomyopathy.

Objective: We hypothesised that, in hypertrophic cardiomyopathy (HCM), late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is progressive and can be predicted by baseline CMR findings and HCM phenotype.

Methods: In this single-centre cohort study, 71 patients with HCM (59±13 years; 48 men) were prospectively enrolled with clinical, echocardiographic and CMR data. Two consecutive CMR scans were performed with a time interval of 582±174 days. The LGE extent was quantified as a proportion of total LV myocardium (%LGE).

Results: LGE was present in 65 patients (91.5%) at the first CMR (CMR-1). In all, LGE extent was significantly increased (p<0.001). A difference in %LGE between the two CMR scans was correlated with the initial %LGE (r=0.44, p<0.001). LGE progression, defined as >4% increase in LGE at the second CMR, was present in 19 patients with non-apical HCM (36.5%), but in only one apical HCM (5.3%). Also, LGE progression rate was significantly higher in non-apical (0.15%/month) versus apical HCM (0.025%/month) (p=0.001). On the multivariate model #1 including only clinical variables (age, history of paroxysmal atrial fibrillation, LV outflow tract obstruction on echocardiography, beta-blocker use, family history of sudden death, family history of HCM, syncope, non-sustained ventricular tachycardia, rate pressure product, and HCM phenotype), only apical HCM phenotype was associated with less LGE progression (p=0.038). On the multivariate model #2 including CMR variables additional to the model #1, %LGE at CMR-1 was the only determinant for LGE progression (p=0.007). When the analysis was limited to patients with preserved EF, results remained unchanged.

Conclusions: Myocardial fibrosis in HCM is a progressive phenomenon. Non-apical phenotype and a higher LGE extent at CMR-1 are both associated with greater LGE progression.