Obesity and the risk of death after acute myocardial infarction

Background

In the general population, obesity is associated with an increased risk of all-cause death. However, the importance of obesity in patients with established coronary heart disease is less well defined.

Methods

As part of the Determinants of Myocardial Infarction Onset Study, we performed a prospective cohort study of 1898 patients hospitalized with confirmed acute myocardial infarction between 1989 and 1994, with a median follow-up of 3.8 years. We assessed all-cause death through December 1995, using the National Death Index. We categorized patients according to WHO criteria for body mass index (BMI). We compared long-term death according to BMI (kg/m²) by using Cox proportional hazards regression.

Results

Of the 1898 eligible patients, 607 (32%) were normal weight (18.5 to 24.9 kg/m²), 832 (44%) were overweight (25.0 to 29.9 kg/m²), 331 (17%) were class I obese (30.0 to 34.9 kg/m²), and 128 (7%) were class II or more obese (≥35.0 kg/m²). A total of 311 patients died during follow-up. After adjustment for potentially confounding risk factors and excluding patients with noncardiac comorbidity, the risk for death appeared to increase linearly, with increasing BMI across all categories (P for trend = .08). The relative risk of death in all obese patients (≥30 kg/m²) was 1.46, compared with those with normal weight (95% CI, 0.98 to 2.17).

Conclusions

We found that BMI appeared to have a positive, graded relation with post-myocardial infarction death. Whether weight reduction and secondary prevention strategies would reverse this effect in obese population remains to be seen.