Mortality, Cardiovascular, and Medication Outcomes in Patients With Myocardial Infarction and Underweight in a Meta-Analysis of 6.3 Million Patients

Although most of the current evidence on myocardial infarction focuses on obesity, there is growing evidence that patients who are underweight have unfavorable prognosis. This study aimed to explore the prevalence, clinical characteristics, and prognosis of this popu-lation at risk. Embase and Medline were searched for studies reporting outcomes in popu-lations who were underweight with myocardial infarction. Underweight and normal weight were defined according to the World Health Organization criteria. A single-arm meta-analysis of proportions was used to estimate the prevalence of underweight in patients with myocardial infarction, whereas a meta-analysis of proportions was used to estimate the odds ratio of all-cause mortality, medications prescribed, and cardiovascular outcomes. Twenty-one studies involving 6,368,225 patients were included, of whom 47,866 were underweight. The prevalence of underweight in patients with myocardial infarction was 2.96% (95% confidence interval 1.96% to 4.47%). Despite having fewer classical car-diovascular risk factors, patients who were underweight had 66% greater hazard for mor-tality (hazard ratio 1.66, 95% confidence interval 1.44 to 1.92, p <0.0001). The mortality of patients who were underweight increased from 14.1% at 30 days to 52.6% at 5 years. Nev-ertheless, they were less likely to receive guideline-directed medical therapy. Relative to subjects with normal weight, Asian populations who were underweight had greater mor-tality risks than those of their Caucasian counterparts (p = 0.0062). In conclusion, in patients with myocardial infarction, those who were underweight tend to have poorer prognostic outcomes. A lower body mass index is an independent predictor of mortality, which calls for global efforts in addressing this modifiable risk factor in clinical practice guidelines.(c) 2023 Elsevier Inc. All rights reserved. (Am J Cardiol 2023;196:1-10)

Automated summary

Although most attention is given to obesity in myocardial infarction research, there is increasing evidence that underweight patients have a poor prognosis. This study aimed to explore the prevalence, characteristics, and outcomes of underweight patients at risk of myocardial infarction. A meta-analysis of studies reporting outcomes in underweight patients with myocardial infarction was conducted, revealing a prevalence of 2.96% and a 66% higher mortality hazard ratio compared to normal weight patients. Underweight patients had increased mortality rates over time and were less likely to receive guideline-directed therapy. Asian populations showed higher mortality risks compared to Caucasian populations. The study emphasizes the need to address underweight as a modifiable risk factor in clinical practice guidelines.