Atrial Fibrillation in Hypertrophic Cardiomyopathy
How does atrial fibrillation (AF) affect the clinical course of hypertrophic cardiomyopathy (HCM)?
This was a single-center, retrospective analysis of 1,558 patients with HCM followed for a mean of 4.8 years. The analysis focused on the 304 patients (mean age 57 years) who had AF.
The AF was paroxysmal in 226 patients (74%) and persistent in 78 patients (26%). A thromboembolic stroke occurred in 18 patients (6%), 9 of whom were not anticoagulated. Embolic events were more common in 66 unanticoagulated patients than in the 233 anticoagulated patients (14% vs. 2%). Survival among the 304 patients with AF was 91% at 4.8 years of follow-up. Compared to age/gender-matched HCM patients without AF, the AF patients did not have a higher incidence of mortality, sudden death, or heart failure. Rhythm-control therapy consisted of amiodarone in 103 patients, sotalol in 78, catheter ablation in 49, and surgical ablation concomitant with myectomy in 72 patients. There was freedom from AF at 1 year in 44% and 75% of patients after catheter and surgical ablation, respectively.
AF does not increase the risk or severity of heart failure among patients with HCM and is not associated with a higher incidence of mortality or sudden arrhythmic death.
Although AF did not result in a higher risk or greater severity of heart failure in this study, clinically it would seem that AF more results in a greater degree of shortness of breath and impaired effort tolerance in patients with than without HCM. This presumably is because the hemodynamic effects of loss of atrioventricular synchrony are amplified when there is a stiff left ventricle. In regards to survival, it should be kept in mind that a follow-up period of <5 years is insufficient to rule out negative effects of AF on outcomes in patients with HCM.
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