Outcomes of Percutaneous Coronary Intervention Stratified by Body Mass Index

Background The relationship between body mass index (BMI) and outcomes after percutaneous coronary intervention (PCI) remains complex. Although obesity is a major risk factor for coronary artery disease, several observational studies have reported comparable or improved outcomes among overweight or obese patients compared with normal-weight patients, a phenomenon described as the "obesity paradox." Whether this paradox persists when patients are stratified across specific BMI categories, particularly among obesity classes, remains incompletely understood. This study evaluated in-hospital outcomes after PCI across BMI categories using a large national inpatient database. Methods  The National Inpatient Sample (NIS) 2016-2020 was queried, and those who underwent PCI were identified using International Statistical Classification of Diseases and Related Health Problems, 10^th Revision (ICD-10) codes. After excluding underweight patients, the study population was classified into Healthy Weight (HW), Overweight (OW), Obesity Class I (OB1), Obesity Class II (OB2), and Obesity Class III (OB3) based on their BMI: 19.9-24.9 kg/m², 25-29.9 kg/m², 30-34.9 kg/m², 35-39.9 kg/m², and ≥40 kg/m², respectively. The primary outcome was in-hospital mortality. Secondary outcomes were predictors of mortality, including stroke, acute kidney injury (AKI), hemorrhage, hematoma, cardiogenic shock, acute heart failure, and acute respiratory failure (ARF). Results There were 58,919 selected PCIs. Of these, 5.1% (3,029) were HW, 9.3% (5,449) were OW, 30.8% (19,895) were OB1, 25.3% (16,650) were OB2, and 30% (18,496) were OB3.  While the HW group showed a higher mortality rate compared to the OB3 group, 2.4 (1.9-2.9, p<0.0001), mortality was less likely in the other subgroups (OW, OB1, and OB2). ARF 9.9 (8.3-11.9, p<0.0001), cardiogenic shock 7.9 (6.7-9.3, p<0.0001), AKI 2.2 (1.9-2.5, p<0.0001), and increasing age 2.4 (1.7-3.6, p = 0.001) were associated with mortality. Conclusion This study revealed that, despite the obesity paradox, among the population with a BMI > 30 kg/m², those with a lower BMI may have a lower mortality risk than their severely obese counterparts.