Body mass index is associated with prognosis in Japanese elderly patients with atrial fibrillation: an observational study from the outpatient clinic

The relationship between body mass index (BMI) and the prognosis of elderly patients with atrial fibrillation (AF) is unknown. We aimed to examine the association of body weight with the clinical outcomes among Japanese elderly patients with a history of documented AF. This observational study of AF patients from an outpatients clinic in Nagoya University Hospital included 413 patients ≥70 years old (99 obese: BMI ≥25 kg/m²; 256 normal weight: BMI 18.5–24.9 kg/m²; and 58 underweight patients: BMI <18.5 kg/m²). The mean age was 77.5 ± 5.6 years. During a mean follow-up of 19.0 months, all-cause death occurred in 23 patients (obese 1 %, normal weight 5.1 %, and underweight 16 %). The major adverse events including all-cause death, stroke or transient ischemic attack, heart failure requiring admission, and acute coronary syndrome were observed in 53 patients (obese 5.1 %, normal weight 13 %, and underweight 26 %). After adjusting for confounding factors, the underweight group had a significantly greater risk for all-cause death [hazard ratio (HR) 2.91, 95 % confidence interval (CI) 1.12–7.60, p = 0.029], and major adverse events (HR 2.45, 95 % CI 1.25–4.78, p = 0.009) than the normal weight group. In contrast, the obese group had a better prognosis in major adverse events compared with the normal weight group (HR 0.34, 95 % CI 0.13–0.89, p = 0.029). In conclusion, lower BMI was independently associated with poor outcomes among older AF patients. The association between obesity and better prognosis in elderly AF patients was also found.