Impact of extreme obesity on outcomes following percutaneous coronary intervention: insights from a large multi-centre registry.

Abstract

Background: Previous studies have reported a protective effect of obesity compared to normal body mass index (BMI) in patients undergoing percutaneous coronary intervention (PCI). However, it is unclear whether this effect extends to the extremely obese. This study sought to examine the impact of extreme obesity (BMI ≥ 40 kg/m2) on clinical outcomes following PCI in a large multi-centre registry.

Methods: A total of 25,645 patients in the Melbourne Interventional Group Registry during 2005–2017 were stratified by World Health Organization-defined BMI categories and compared. Of these, 24.6% had normal BMI, 0.9% were underweight (BMI < 18.5 kg/m2), and 3.3% were extremely obese. The primary endpoint was National Death Index (NDI)-linked mortality. Mean time to NDI-linked mortality was 4.9 ± 3.4 years.

Results: As BMI increased, mean age decreased, while the prevalence of diabetes increased (p < 0.001). Those at the extremes of weight were more likely to be female (BMI < 18.5 kg/m2: 39.7% female; BMI ≥40 kg/m2: 41.8% female). Overall NDI-linked mortality was highest for underweight patients (37.7%) and lowest for the moderately obese (12.2%). After adjustment for age, comorbidities including renal and left ventricular function, and cardiogenic shock. A U-shaped association was observed between BMI categories and adjusted hazards ratio for NDI-linked mortality. Overweight and mildly obese patients were at lowest risk, while both underweight and extremely obese patients had higher risk.

Conclusion: An obesity paradox was still apparent in contemporary practice, with elevated BMI up to 35 kg/m2 associated with reduced mortality after PCI. However, this effect appeared to not extend to patients with extreme obesity.