Background: The prevalence of obesity among Japanese acute type A aortic dissection (ATAAD) patients and its effect on repair outcomes remain to be elucidated. Methods and Results: The prevalence of obesity (body mass index [BMI] ≥30.0 kg/m2) among 1,059 patients (mean [±SD] age 64.3±12.7 years) who underwent ATAAD repair between 1990 and 2018 was compared with that among the general Japanese population (National Health and Nutrition Survey data). The prevalence of obesity among male patients (17.1% [6/35], 20.0% [18/90], and 14.4% [20/139] for those aged 20–39, 40–49, and 50–59 years, respectively) was significantly higher than that among the age- and sex-matched general population. The 1,059 patients were divided into groups according to weight (normal [BMI 48 h (44.5%, 60.1%, and 78.3%, respectively), and in-hospital mortality (7.0%, 7.3%, and 17.4%, respectively), but not in 30-day survival. Shock, visceral malperfusion, operation time >360 min, obesity, and coronary malperfusion were identified as predictors of in-hospital mortality. Conclusions: The prevalence of obesity is increased among Japanese male patients with ATAAD aged ≤59 years. Obesity may increase these patients’ operative risk; overweight does not.
