Obesity Paradox and Long-term Cardiovascular Outcomes in Patients with Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

risk factor for cardiovascular diseases, and it is commonly assessed through anthropometric measures, such as body mass index (BMI), waist circumference (WC), and waistto-height ratio (WHtR).The presence of excess adipose tissue has been consistently linked with an increased Objectives: Obesity is a known modifiable risk factor for cardiovascular disease, and guidelines recommend maintaining a body mass index of 20-25 kg/m 2 to reduce cardiovascular risk.However, several studies have reported that obese patients with acute coronary syndrome (ACS) may have better short-and long-term survival than their normal-weight counterparts-a phenomenon known as the "obesity paradox." The effect of this paradox in ACS patients treated exclusively with percutaneous coronary intervention (PCI) remains unclear.This retrospective, two-center cohort study aimed to evaluate the impact of BMI on long-term mortality in ACS patients undergoing PCI, with a 3 years follow-up period.Methods: A total of 1,198 patients were categorized according to BMI as normal weight (n=321), overweight (n=753), and obese (n=124).Survival across BMI categories was evaluated using Kaplan-Meier analysis with log-rank testing.Univariate and multivariable Cox proportional hazards regression models (backward likelihood ratio method) were performed to identify predictors of long-term mortality.Results: In-hospital mortality was lowest among obese patients (2.2%) compared to overweight (2.8%) and normal-weight patients (7.4%) ( 2 =12.448; p=0.002).Over a 3 years follow-up, mortality remained significantly lower in the obese (6.5%) and overweight (8.5%) groups compared with the normal-weight group (20.1%) ( 2 =30.662; p<0.001).In multivariable analysis, smoking increased mortality risk by approximately 50% (Hazard ratio [HR]: 1.508; 95% confidence interval [CI]: 1.030-2.208;p=0.035), whereas obesity (HR: 0.297; 95% CI: 0.128-0.688;p=0.005) and overweight (HR: 0.404; 95% CI: 0.282-0.578;p<0.001) significantly reduced mortality risk.Conclusion: Although obesity remains a significant risk factor for the development of cardiovascular disease, the present findings support the existence of an obesity paradox among ACS patients treated with PCI.Obese and overweight patients demonstrated a 60-70% lower risk of long-term mortality compared with normal-weight patients.These results highlight the need for a more nuanced approach to risk stratification and treatment planning in this patient group.