Magnetic Resonance Left Ventricle Mass-Index/Fibrosis: Long-Term Predictors for Ventricular Arrhythmia in Hypertrophic Cardiomyopathy-A Retrospective Registry

Objective: We aimed to study the long-term association of LV mass index (LV_MI) and myocardial fibrosis with ventricular arrhythmia (VA) in a population of patients with confirmed hypertrophic cardiomyopathy (HCM) using cardiac magnetic resonance imaging (CMR). Methods: We retrospectively analyzed the data in consecutive HCM patients confirmed on CMR referred to an HCM clinic between January 2008 and October 2018. Patients were followed up yearly following diagnosis. Baseline demographics, risk factors and clinical outcomes from cardiac monitoring and an implanted cardioverter defibrillator (ICD) were analyzed for association of LV_MI and LV late gadolinium enhancement (LV_LGE) with VA. Patients were then allocated to one of two groups according to the presence of VA (Group A) or absence of VA (Group B) during the follow-up period. The transthoracic echocardiogram (TTE) and CMR parameters were compared between the two groups. Results: A total of 247 patients with confirmed HCM (age 56.2 ± 16.6, male = 71%) were studied over the follow-up period of 7 ± 3.3 years (95% CI = 6.6-7.4 years). LV_MI derived from CMR was higher in Group A (91.1 ± 28.1 g/m² vs. 78.8 ± 28.3 g/m², p = 0.003) when compared to Group B. LV_LGE was higher in Group A (7.3 ± 6.3% vs. 4.7 ± 4.3%, p = 0.001) when compared to Group B. Multivariable Cox regression analysis showed LV_MI (hazard ratio (HR) = 1.02, 95% CI = 1.001-1.03, p = 0.03) and LV_LGE (HR = 1.04, 95% CI = 1.001-1.08, p = 0.04) to be independent predictors for VA. Receiver operative curves showed higher LV_MI and LV_LGE with a cut-off of 85 g/m² and 6%, respectively, to be associated with VA. Conclusions: LV_MI and LV_LGE are strongly associated with VA over long-term follow-up. LV_MI requires more thorough studies to consider it as a risk stratification tool in patients with HCM.