Impact of Obesity on Microvascular Obstruction and Area at Risk in Patients After ST-Segment-Elevation Myocardial Infarction: A Magnetic Resonance Imaging Study

Background: Better survival for overweight and obese patients after ST-segment elevation myocardial infarction (STEMI) has been demonstrated. The association between body mass index (BMI), microvascular obstruction (MVO), and area at risk (AAR) after STEMI was evaluated. Methods: A prospective observational study was performed to enrolled patients undergoing primary percutaneous coronary inter-vention (pPCI) for STEMI and cardiac magnetic resonance was performed within 5-7 days. Patients were classified as normal weight (18.5 & LE;BMI < 24.0 kg/m2), overweight (24.0 & LE;BMI < 28.0 kg/m2), or obese (BMI 228 kg/m2). Results: Among 225 patients undergoing pPCI, 67 (30.00%) were normal weight, 113 (50.22%) were overweight, and 45 (20.00%) were obese. BMI 228 kg/m2 was significantly associated with less risk of MVO when compared with a normal BMI after multivariable adjustment (overweight: HR 0.29, 95% CI 0.13-0.68, p = 0.004). Compared with normal weight patients, obese and overweight patients tend to have larger hearts (greater left ventricular end-diastolic volume [LVEDV] and left ventricular [LV] mass). In adjusted analysis, increased BMI was significantly associated with a smaller AAR. In addition, obese patients had a smaller AAR ([3 = -0.252, 95% CI -20.298--3.244, p = 0.007) and AAR, % LV mass ([3 = -0.331, 95% CI -0.211--0.062, p < 0.001) than normal weight patients. Conclusion: Obesity (BMI 228 kg/m2) is independently associated with lower risks of MVO and a smaller AAR, % LV mass than normal weight patients among subjects undergoing pPCI for STEMI.

Automated summary

This study found that obese and overweight patients undergoing pPCI for STEMI have better survival rates compared to normal weight patients. Obese patients also have a lower risk of microvascular obstruction and a smaller area at risk/left ventricular mass.