Implications of primary bradycardia in patients with hypertrophic cardiomyopathy.

BACKGROUND

Hypertrophic cardiomyopathy (HCM) with tachyarrhythmias has been extensively studied in recent years. The characteristics of primary bradycardia in HCM remain largely unknown.

OBJECTIVE

This study aimed to comprehensively investigate the prevalence, clinical features, and prognosis of primary bradycardia in patients with HCM in a large cohort.

METHODS

A total of 1055 HCM patients with electrocardiogram results were recruited by Fuwai Hospital between 1999 and 2019. The study end points were all-cause death, cardiovascular death, and heart failure (HF)-related death.

RESULTS

The final analysis included 1003 HCM patients, of whom 86 were identified as having primary bradycardia. Of those, 54 patients had sinus node dysfunction (SND) and 43 patients had atrioventricular block (AVB); 11 patients had both SND and AVB. Fibrosis was more severe in patients with primary bradycardia in HCM, and the patterns of fibrosis were different. Median follow-up was 6.8 years. SND only and AVB only were significantly associated with an increased risk of all-cause death (SND only: adjusted hazard ratio [aHR], 2.219, P = .012; AVB only: aHR, 2.425, P = .007), cardiovascular death (SND only: aHR, 2.737, P = .019; AVB only: aHR, 3.853, P < .001), and HF-related death (SND only: aHR, 4.217, P = .027; AVB only: aHR, 9.367, P < .001). The coexistence of SND and AVB was associated with an even worse prognosis than with SND or AVB alone.

CONCLUSION

Primary bradycardia, including SND and AVB, independently increases the risk of all-cause death, cardiovascular death, and HF-related death in patients with HCM. Our study provides an important reference for understanding the full picture of HCM patients with primary bradycardia.