Impact of prolonged QTc interval on mortality risk with hypertrophic cardiomyopathy.

The association between corrected QT (QTc) interval and life-threatening cardiac events in patients with hypertrophic cardiomyopathy (HCM) remains unclear. This study sought to investigate whether the prolonged QTc was associated with HCM-related death in patients with HCM. We included 445 patients with HCM (mean age 51 ± 16 years, 67% men). The QTc interval was measured at the time of the initial evaluation and the patients were classified into those with and without QTc prolongation, which was defined as a QTc interval >450 ms. HCM-related death was defined as a combined endpoint of sudden death or potentially lethal arrhythmic events, heart failure-related death, and stroke-related death. Prolonged QTc interval was found in 120 patients (26.4%) at the time of enrollment. Over a median (IQR) follow-up period of 8.1 (4.6-11.9) years, a total of 67 patients (15.1%) experienced HCM-related deaths including 57 (12.8%) with the endpoint of sudden death or potentially lethal arrhythmic events. In a multivariable analysis that included prolonged QTc interval and the risk factors for life-threatening events, prolonged QTc interval was independently associated with an HCM-related death (adjusted hazard ratio [HR]: 1.91; 95% confidence interval [CI]: 1.16-3.16; p = .011) and this trend also persisted for the combined endpoint of sudden death or potentially lethal arrhythmic events (adjusted HR: 2.01: 95% CI: 1.17-3.46; p = .012). In this cohort of patients with HCM, QTc prolongation may be associated with HCM-related death, including the endpoint of sudden death or potentially lethal arrhythmic events.