Impact of obesity on 1-year major adverse cardiac events after primary PCI for STEMI

Obesity is increasing in all regions of Switzerland. Multiple studies have described the "obesity paradox" suggesting a protective effect of obesity on the occurrence of major adverse cardiovascular events (MACE) after ST-segment elevation myocardial infarction (STEMI) treated with percutaneous coronary intervention (PCI).

This study aimed to assess the impact of obesity on MACE in STEMI patients undergoing PCI.

We analyzed data from the Fribourg STEMI Fast-Track prospective registry in a retrospective, single-center cohort study. Adult patients were classified as obese (BMI ≥ 30 kg/m²) or non-obese (BMI < 30 kg/m²) and followed for 12 months. The primary endpoint was a composite MACE including all-cause death, recurrent acute coronary syndrome (ACS) (STEMI, NSTEMI and unstable angina (UA)), stroke, stent thrombosis, unscheduled revascularisation, and major bleeding (BARC 3-5). Secondary endpoints included stratification according three obesity stages to evaluate 1-year MACE-free survival, as well as assessment of individual MACE components, delays in care, mode of presentation, and clinical and procedural characteristics. Kaplan-Meier analysis with log-rank testing and Cox regression were used to evaluate outcomes.

A total of 1043 patients were included between June 2008 and October 2025, of whom 214 (21%) were obese and 829 (79%) were non-obese. Obese patients were slightly younger (60.00 (53.00, 70.00) vs 62.00 (53.00, 72.00) years, p = 0.037), with a similar proportion of women (21% vs 25%, p = 0.299). At 12 months, MACE-free survival was similar between groups (log-rank p = 0.76), and obesity was not associated with MACE after adjustment. No differences were observed in individual components of the composite endpoint. Pre-hospital delay was comparable, whereas first medical contact-to-revascularisation (FMC-to-REVASC) time was longer in obese patients (0.78 vs 0.57 h, p < 0.001), with no difference in total ischemic time. Obese patients were less likely to present via ambulance (31% vs 38%) and more likely to self-present to the emergency department (32% vs 24%; p = 0.037). Clinical presentation, procedural characteristics, and coronary anatomy were similar between groups.

In this contemporary STEMI cohort, obese patients treated with primary PCI did not experience higher 1-year MACE rates than non-obese patients. However, obesity was associated with differences in care pathways and longer in-hospital delays, without impact on clinical outcomes.