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/m2), normal weight (20.0-24.9 kg/m2), overweight (25.0-29.9 kg/m2) and obese (≥30.0 kg/m2). 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. (Circ J 2008; 72: 521 - 525)