Impact of Body Mass Index on Postoperative Atrial Fibrillation in Patients With Hypertrophic Cardiomyopathy Undergoing Septal Myectomy

Background Obesity is an established cardiovascular risk factor in patients with hypertrophic cardiomyopathy. Postoperative atrial fibrillation (POAF) is one of the most common complications after surgery in patients with obstructive hypertrophic cardiomyopathy (OHCM). We aimed to determine the impact of body mass index (BMI) on the occurrence of POAF in patients with OHCM who underwent septal myectomy. Methods and Results In all, 712 OHCM patients without previous atrial fibrillation who underwent septal myectomy were identified. Patients were stratified into 3 groups based on BMI. Of these, 224 (31.5%) had normal weight (BMI<24 kg/m 2 ), 339 (47.6%) were overweight (BMI, 24 to <28 kg/m 2 ), and 149 (20.9%) were obese (BMI≥28 kg/m 2 ). Overweight and obese patients had increased levels of left atrial diameter ( P <0.001) and left ventricular end‐diastolic diameter ( P <0.001), compared with patients with normal weight. Among 184 patients (25.8%) developing POAF, 32 cases (14.3%) occurred in the normal weight group, 100 cases (29.5%) occurred in the overweight group, and 52 cases (34.9%) occurred in the obese group ( P <0.001). Logistic regression analysis indicated that overweight (odds ratio [OR]: 2.161, 95% CI, 1.333–3.503; P =0.002) or obesity (OR, 2.803; 95% CI, 1.589–4.944; P <0.001), age (OR, 1.037; 95% CI, 1.018–1.057; P <0.001), and left atrial diameter (OR, 1.060; 95% CI, 1.027–1.095; P <0.001) were independently associated with the occurrence of POAF in patients with OHCM. Conclusions Overweight and obesity are strong predictors of POAF in patients with OHCM. Strategies aimed at lowering BMI may be a potential way to prevent POAF.