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.