Impact of body mass index on outcomes in acute type A aortic dissection

Background Elevated body mass index (BMI) is associated with adverse outcomes after cardiac surgery, but its impact in acute type A aortic dissection (ATAAD) surgery is unclear. We assessed the relationship between BMI and outcomes after ATAAD repair. Methods An institutional retrospective cohort review was undertaken of all consecutive patients who underwent repair of ATAAD between July 2014 and December 2022 ( n = 398). Patients were stratified by BMI into three groups: ‘non-obese’ [BMI < 30 kg/m 2 ; median 26.0 (23.0, 27.7) kg/m 2 ] ( n = 248), ‘Obesity Class I’ [30 ≤ BMI < 35 kg/m 2 ; median 31.9 (30.8, 33.4) kg/m 2 ] ( n = 81), and ‘Obesity Class II+’ [BMI ≥ 35 kg/m 2 ; median 38.9 (36.4, 41.9) kg/m 2 ] ( n = 69). Multivariable logistic regression was utilized to assess the relationship between BMI and 30-day mortality, stroke, and duration of ventilation. Results Thirty-day operative mortality for the entire cohort was 12.8% ( n = 51). The Obesity Class I cohort was associated with decreased odds of 30-day mortality [OR = 0.18, 95% CI: (0.06–0.62), p = 0.006] compared to the non-obese cohort, whereas the Obesity Class II + was not. Diabetes [OR = 2.9, 95% CI: (1.32–6.41), p = 0.008], history of lower extremity ischemia [OR = 4.27, 95% CI: (2.11–8.62), p < 0.001], age [OR = 1.04, 95% CI: (1.01–1.07), p = 0.005], duration of cardiopulmonary bypass [OR = 1.005, 95% CI: (1.00–1.01), p = 0.027], and units of intraoperative red blood cells received [OR = 1.08, 95% CI: (1.01–1.16), p = 0.028] were associated with increased 30-day mortality. There was no significant association between BMI groups and post-operative stroke or duration of ventilation. Conclusion The obesity paradox in cardiac surgery remains incompletely understood. In this cohort, BMI was not associated with increased 30-day mortality following ATAAD repair, with class I obesity demonstrating lower adjusted mortality. These findings support the continued practice of expeditious surgical intervention for ATAAD regardless of BMI.