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.