Objective: Recent research indicates that obesity is not a uniform condition, but rather encompasses distinct phenotypes with varying health risks 1–3. Body Mass Index (BMI), while commonly used, fails to capture these nuances and may not accurately reflect obesity-related health risks across different BMI categories 4,5. This study aimed to examine the effects of obesity phenotypes in patients with heart disease requiring cardiac surgery.
Methods: A retrospective review of hospital records was conducted for patients aged 18 and older who underwent cardiac surgery in one tertiary hospital in New Zealand between March and September 2023. Patients were categorised into six groups based on BMI and metabolic status.
Results: Of 265 patients, 78 (29.4%) underwent coronary artery bypass graft (CABG) surgery, 129 (48.7%) had valve surgery, 52 (19.6%) had a combination of CABG-valve surgery, and 6 (2.3%) had other surgery. The number of CABG and CABG-valve surgeries was greater among metabolically unhealthy patients compared to their metabolically healthy counterparts. Conversely, valve surgery was more frequent in metabolically healthy groups than in metabolically unhealthy groups. Simple logistic regression showed no significant association between BMI obesity categories and cardiac surgeries, but obesity phenotypes were significantly associated. Multivariate logistic regression analysis confirmed these associations, with adjusted odds ratio (OR) of CABG surgery for metabolically unhealthy normal weight, overweight, and obesity were 4.303 (1.139-16.261), 8.297 (2.538-27.119), and 6.282 (1.932-20.420), respectively. For valve surgery, the ORs of metabolically unhealthy groups were 0.165 (0.49-0.554) for normal weight, 0.103 (0.035-0.307) for overweight, and 0.176 (0.064-0.485) for obesity. Only metabolically unhealthy normal weight was significantly associated with CABG-valve surgery, with an adjusted OR of 6.851 (1.210-38.782).
Conclusion: Obesity phenotyping using BMI and metabolic health status is associated with the likelihood of cardiac surgery. The presence of metabolic abnormalities across the BMI range may increase the odds of cardiac surgery.