Predictors of future onset of atrial fibrillation in hypertrophic cardiomyopathy.

Background: Novel predictors of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM) are desirable.

Aim: To detect new multimodality imaging variables predictive of de novo AF in HCM.

Methods: Consecutive patients with HCM underwent clinical assessment and 48-hour Holter electrocardiography to detect AF episodes. Left ventricular (LV) morphology, function and fibrosis, and the left atrium (LA) were characterized by cardiac magnetic resonance. Mitral valve, systolic pulmonary artery pressure, LV filling and maximum gradients were assessed by echocardiography. Patients with no previous history of AF were followed with Holter recordings.

Results: Two hundred and nine patients were included (mean age 53±16 years; 140 men), 46 (22%) of whom had a history of AF and a longer duration from HCM diagnosis, more frequent use of heart failure medication, a higher systolic pulmonary artery pressure, a lower LV ejection fraction, a higher extent of LV fibrosis and prevalence of fibrosis on right ventricular (RV)-LV insertions, a higher LA volume and lower LA phasic function. Patients with no AF at inclusion were followed for 26 (17-42) months, and 15 (9%) developed de novo AF. Among clinical characteristics, New York Heart Association class was the only significant AF predictor in the multivariable analysis (hazard ratio 2.65 per class, 95% confidence interval [CI] 1.15-6.10; P=0.02). Among imaging characteristics, two independent predictors were identified: myocardial fibrosis on RV insertions (hazard ratio 2.8, 95% CI 1.3-5.9; P=0.008); and LA volume (hazard ratio 1.03 per mL/m, 95% CI 1.01-1.06; P=0.006).

Conclusions: AF in HCM is predicted by New York Heart Association class, LA volume and LV fibrosis on RV-LV insertions on cardiac magnetic resonance imaging. The mechanisms relating the ventricular phenotype to AF should be clarified in future studies.