Impact of body mass index on in-hospital outcomes after percutaneous coronary intervention for ST segment elevation acute myocardial infarction.

Background: The impact of body mass index (BMI) on outcomes after primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) remains unclear.

Methods And Results: A total of 3,076 patients undergoing PCI for AMI within 48 h after symptom onset were studied. Patients were divided into 4 groups according to baseline BMI: lean (<20 kg/m(2)), normal weight (20.0-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)) and obese (>or=30.0 kg/m(2)). Obese patients were younger and had a higher frequency of diabetes mellitus, hyperlipidemia, hypertension and smoking. Lean patients were older, usually women and had a lower frequency of the aforementioned risk factors. Killip class on admission, renal insufficiency, and final Thrombolysis In Myocardial Infarction (TIMI) flow grade did not differ among the 4 groups. In lean, normal weight, overweight and obese patients, in-hospital mortality was 9.2%, 4.4%, 2.5% and 1.8%, respectively (p<0.01). Multivariate analysis showed that compared with normal weight patients, odds ratios for in-hospital death in lean, overweight and obese patients were 1.92, 0.79 and 0.40, respectively (p=NS). Independent predictors were age, Killip class on admission, renal insufficiency and final TIMI flow grade.

Conclusion: BMI itself had no impact on in-hospital mortality in patients undergoing primary PCI for AMI. The phenomenon ;obesity paradox' may be explained by the fact that obese patients were younger at presentation.