Prognostic Implication of First‐Degree Atrioventricular Block in Patients With Hypertrophic Cardiomyopathy

Background The association between first‐degree atrioventricular block (AVB) and life‐threatening cardiac events in patients with hypertrophic cardiomyopathy (HCM) remains unclear. This study sought to investigate whether presence of first‐degree AVB was associated with HCM‐related death in patients with HCM. Methods and Results We included 414 patients with HCM (mean age, 51±16 years; 64.5% men). The P‐R interval was measured at the time of the initial evaluation and patients were classified into those with and without first‐degree AVB, which was defined as a P‐R interval ≥200 ms. HCM‐related death was defined as a combined end point of sudden death or potentially lethal arrhythmic events, heart failure–related death, and stroke‐related death. First‐degree AVB was noted in 96 patients (23.2%) at time of enrollment. Over a median (interquartile range) follow‐up period of 8.8 (4.9–12.9) years, a total of 56 patients (13.5%) experienced HCM‐related deaths, including 47 (11.4%) with a combined end point of sudden death or potentially lethal arrhythmic events. In a multivariable analysis that included first‐degree AVB and risk factors for life‐threatening events, first‐degree AVB was independently associated with an HCM‐related death (adjusted hazard ratio, 2.41; 95% CI, 1.27–4.58; P=0.007), and this trend also persisted for the combined end point of sudden death or potentially lethal arrhythmic events (adjusted hazard ratio, 2.60; 95% CI, 1.28–5.27; P=0.008). Conclusions In this cohort of patients with HCM, first‐degree AVB may be associated with HCM‐related death, including the combined end point of sudden death or potentially lethal arrhythmic events.