Impact of overweight on myocardial infarct size in patients undergoing primary percutaneous coronary intervention: A magnetic resonance imaging study

•Myocardial infarct size was evaluated using CMR in patients undergoing primary PCI for STEMI.•Overweight patients with a BMI ≥ 25 kg/m2 showed a smaller infarct size and area at risk than patients with normal weight.•BMI ≥ 25 kg/m2 was independently associated with a smaller infarct size than normal BMI.

ObjectiveAlthough obesity is a risk factor for cardiovascular disease and mortality, several studies have reported that patients with obesity who have suffered acute myocardial infarction or have undergone percutaneous coronary intervention (PCI) have better clinical outcomes than their normal weight counterparts. We evaluated the impact of overweight on myocardial infarct size in patients undergoing primary PCI for ST-segment elevation myocardial infarction (STEMI).MethodsWe performed contrast-enhanced magnetic resonance imaging on 193 patients undergoing primary PCI for STEMI. Infarct size was measured with delayed-enhancement imaging and the area at risk was quantified on T2-weighted images.ResultsBaseline characteristics and angiographic findings were not significantly different between the normal weight group (body mass index [BMI] < 25 kg/m2, n = 110) and the overweight group (BMI ≥ 25 kg/m2, n = 83). The median percent infarct volume and area at risk were significantly smaller in the overweight group than the normal weight group (17.9% [9.0-24.9%] vs. 20.8% [11.4-33.1%], p = 0.04 and 29.4% [20.5-37.6%] vs. 36.0% [25.7-49.6%], p < 0.01, respectively). However, the myocardial salvage index was not different between the 2 groups (overweight group vs. normal weight group, 43.2% vs. 39.2%, p = 0.69). BMI ≥ 25 kg/m2 was an independent predictor of smaller infarct size in multivariate analysis (Odds ratio 0.51, 95% Confidence interval 0.27-0.97, p = 0.039).ConclusionOverweight (BMI ≥ 25 kg/m2) is independently associated with smaller infarct size in patients undergoing primary PCI for STEMI.