Gender-specific differences in body mass index and cardiovascular risk adversely impact survival after aortic valve replacement.

Background: There is a lack of evidence on association between gender specific differences in obesity and cardiovascular risk after isolated surgical aortic valve replacement (AVR) and its impact on outcomes and long-term survival. The aim of this study was to assess the impact of obesity on perioperative outcomes and long-term survival after isolated AVR.

Methods: In this retrospective, single-centre study, we included all patients who underwent isolated AVR between April 2000 and December 2019 from the cardiac surgery database of the Southampton General Hospital (Patient Administration System, e-CAMIS, Yeadon, Leeds, UK). Patients with infective endocarditis, re-sternotomy, other concomitant cardiac procedures, homografts, autografts and emergency operations were excluded. Univariable regression analysis was performed to identify predictors of in-hospital mortality. Hazard ratios were calculated using a Cox proportional hazards model.

Results: Total of 2,398 patients were included in the study and two groups of patients were compared: body mass index (BMI) 25-34.9 kg/m² (n=2,000) and BMI ≥35 kg/m² (n=398) based on sensitivity modelling. Actuarial survival was comparable across BMI groups at 12.5and 12.7 years for BMI 25-34.9 kg/m² and BMI ≥35 kg/m², respectively (P=0.75 log-rank). Long-term survival was specifically worse for patients with high BMI and composite cardiovascular risk of hypertension, diabetes mellitus, and current smoking [hazard ratio (HR) 1.93, 95% confidence interval (CI): 1.45-2.58, P<0.001] and patients with moderate-to-severe patient prosthesis mismatch (PPM) (effective orifice areas index ≤0.85 cm²/m²) (HR 1.17 95% CI: 0.98-1.39, P=0.08). Median survival time for females was 11.5 years [interquartile range (IQR): 10.3-12.3 years] versus 14.2 years (IQR: 12.7-15.7 years) for males (log-rank P=0.006), although gender was not a significant predictor of long-term survival after adjusting for covariates. Moderate-severe PPM was associated with significantly worse survival in females (log-rank P<0.01), compared to males for whom this difference was not significant (log-rank P=0.21).

Conclusions: Obesity with composite risk factors (hypertension, diabetes mellitus and active smoking) is associated with adverse survival. We did not observe gender-specific differences in long-term survival among specific BMI groups of patients.