Relationship of obesity to adverse events in myocardial infarction patients without primary percutaneous coronary intervention: results from the Occluded Artery Trial (OAT)

Abstract

Objective: Our goal was to investigate the “obesity paradox” in myocardial infarction populations without primary percutaneous coronary intervention (PPCI).

Methods: The Occluded Artery Trial (OAT, Clinicaltrials.gov: NCT00004562) is a randomized, multicenter study to investigate the influence of routine percutaneous coronary intervention (PCI) on the clinical outcomes of myocardial infarction patients without PPCI. We stratified these patients into three groups according to body mass index (BMI): normal, 18.5 kg/m² ≤ BMI < 25 kg/m²; overweight, 25 kg/m² ≤ BMI < 30 kg/m²; obese, BMI ≥ 30 kg/m². The purpose of our study was to investigate the effects of BMI on the primary endpoint (all-cause mortality) and the secondary endpoint (cardiac death, non-cardiac death or New York Heart Association [NYHA] class IV heart failure) in the population enrolled in the OAT.

Results: A total of 2153 patients (99.4%) constituted the final study population. We found that obese patients were younger and were more likely to have cardiovascular risk factors compared with other BMI groups. A U-shaped relationship was observed between BMI and all-cause mortality. The adjusted hazard ratios (HRs) were 0.892 (95% CI: 0.658–1.210, p = .460) for normal weight patients and 0.671 (95% CI: 0.508–0.888, p = .013) for overweight patients compared with obese patients. The same pattern was also observed for non-cardiac death. The adjusted HRs were 0.919 (95% CI: 0.601–1.40, p = .663) for normal weight patients and 0.524 (95% CI: 0.346–0.792, p = .004) for overweight patients compared with obese patients. We did not find any statistical differences among BMI categories in terms of cardiac death or NYHA class IV heart failure.

Conclusions: A U-shaped relationship was observed between BMI and all-cause mortality or non-cardiac death. Overweight patients have the lowest risk of all-cause mortality, which may be attributed to their having the lowest risk of non-cardiac death of the groups studied.

Keywords:

• Obesity paradox
• myocardial infarction
• primary percutaneous coronary intervention
• all-cause mortality

Transparency

Declaration of funding

The authors declare that they have no sources of funding.

Author contributions

S.G. and Z.X. designed the study and provided methodological expertise. J.P. drafted the manuscript. J.H. and X.H. drafted the tables and figures. All authors read, provided critical feedback and approved the final manuscript.

Declaration of financial/other relationships

No potential conflict of interest was reported by the authors. CMRO peer reviewers on this manuscript have received an honorarium from CMRO for their review work but have no relevant financial or other relationships to disclose.

Acknowledgements

The authors acknowledge the Biologic Specimen and Data Repository Information Coordinating Center (BioLINCC).