Prognostic Implications of Coronary Microvascular Dysfunction in ST ‐Elevation Myocardial Infarction by Obesity Status

Aims This study aimed to assess the association of coronary microvascular dysfunction (CMD) assessed by the angiography‐derived index of microcirculatory resistance (angio‐IMR) with long‐term cardiovascular outcomes in ST‐elevation myocardial infarction (STEMI) patients stratified by obesity categories. Materials and Methods In this multicentre prospective cohort, STEMI patients undergoing primary percutaneous coronary intervention (PPCI) were enrolled. Patients were stratified by obesity categories (healthy weight: BMI < 24 kg/m 2 ; overweight: 24–28 kg/m 2 ; obesity: ≥ 28 kg/m 2 ). CMD was defined as angio‐IMR > 40 U. Results Of 497 STEMI patients, CMD prevalence was comparable across BMI groups ( p = 0.875). The cumulative incidence of MACCE was significantly higher in the CMD group than in the non‐CMD group among patients with obesity (33.3% vs. 15.0%, log‐rank p = 0.016), but not among those with overweight (19.6% vs. 15.9%, log‐rank p = 0.565) and healthy weight (20.7% vs. 17.4%, log‐rank p = 0.673). CMD independently predicted MACCE in obesity (adjusted HR; p = 0.020), with consistent results for continuous angio‐IMR (adjusted HR 1.03, p < 0.001). No associations existed in patients with overweight or healthy weight. Additionally, CMD was associated with a higher prevalence of intramyocardial haemorrhage exclusively in obesity (adjusted OR 4.40, p = 0.003) and overweight (adjusted OR 2.65, p = 0.007). Conclusion CMD assessed by angio‐IMR is an independent predictor of MACCE in STEMI patients with obesity, but not those without obesity. Patients with obesity and STEMI who have CMD may represent a high‐risk subgroup for future trials of microvascular‐protective therapies.