Influence of BMI on Short and Long-Term Outcomes in Patients With STEMI and LV Dysfunction

Recent studies suggest an obesity paradox in individuals with myocardial infarction with better outcomes in obese relative to normal weight patients. We assessed the influence of body mass index (BMI) on early and long-term outcomes in patients with ST elevation myocardial infarction (STEMI) and left ventricular (LV) dysfunction.

Outcomes were assessed according to BMI status in 478 consecutive patients with STEMI and LV dysfunction (ejection fraction [EF]<40%) admitted to Westmead Hospital between 1 January 2004 and 16 April 2014. Normal weight, overweight and obesity were defined as BMI < 25, 25-29.9, and ≥30 kg/m2, respectively.

Obese patients were significantly younger (p = 0.01) and were more likely to have hypertension and diabetes (p = 0.04 and 0.001 respectively). In hospital outcomes and 30-day major adverse cardiac events (MACE) were similar in all three groups. There was no difference in recurrent myocardial infarction (MI) and target vessel revascularisation (TVR) during long-term follow-up (mean follow-up 809 days). Overall mortality following hospital discharge was significantly lower in overweight and obese patients. Adjusted hazard ratio for all-cause mortality in normal weight patients compared to overweight patients was 2.4 (95% C.I 1.1-5.3, p= -0.03). The adjusted hazard ratio for all-cause mortality in normal weight patients in comparison to obese patients was 2.7 (95% C.I, 1 -7.4, p = 0.05). Left ventricular ejection fraction (LVEF) and age were other predictors of all-cause mortality.

Normal weight, overweight and obese patients with STEMI and LV dysfunction had similar in hospital outcomes and 30-day outcomes. Long-term all-cause mortality was, however, higher in normal weight patients suggesting the presence of an obesity paradox in this cohort.