Objective

Despite exhaustive analysis suggesting otherwise, many cardiac surgeons & anaesthetists persist in the belief that obesity is an independent predictor of risk in cardiac surgery. In aortic valve surgery there is a growing body of literature to suggest that, whilst low BMI may be associated with poor outcomes, high BMI is not: the so-called ‘obesity paradox’. This single centre retrospective study examines our experience of the phenomenon.

Methods

Retrospective analysis of isolated first-time aortic valve replacement (AVR) in a prospectively collected database (2011-2015). Obese (BMI≥30) & non-obese (BMI<30) patients were compared for: demographics, pre-, intra- & post-operative variables. Statistical methods included descriptive tests and Chi-square test to detect significance different variables between groups. Variables were fed into a logistic regression model to determine the impact of obesity on mortality and morbidity.

Results

There were 467 patients. 284 were male (61%), 165 (35.3%) were obese. Mean logistic EuroSCORE was 6.6±6 in the non-obese group & 6.6±5 in the obese group (μ±SD). Diabetes mellitus, hypertension, renal failure, COPD, and carotid artery disease were more common in obese patients. Renal failure and multi-organ failure were more common in the obese and there were more deaths (3.1% vs 0%, p<0.005). Logistic regression confirmed obesity, female gender, and renal dialysis as predictors of death.

Conclusion

The number of obese patients undergoing AVR is increasing over time. Pre-operative BMI≥30 is associated with an increased risk of death in patients undergoing isolated first-time AVR in our institution. This increased risk may be independent of other associated co-morbidities and appears to confound the so-called ‘obesity paradox’ reported by other authors. High BMI should be taken into account when considering alternative strategies in the surgical management of aortic valve disease.