Endocrine Abstracts

Introduction: Obesity is an independent risk factor of coronary artery disease, and it has also been shown to be associated with increased survival in some instances such as myocardial infarction – dubbed the ‘Obesity Paradox’. However, there is a paucity of studies identifying the type of myocardial infarction – non-ST-segment elevation MI (NSTEMI) or ST-segment MI (STEMI) – that may be differentially prevalant according to BMI (body mass index) class. Indeed, STEMI has been shown to have better long-term mortality compared to NSTEMI, and may contribute towards improved survival among the obese population.

Hypothesis: We hypothesised whether STEMI or NSTEMI is greater in obese patients and if increasing BMI correlates with increased likelihood of STEMI.

Methods: We retrospectively analysed 1649 patients from a larger cohort of patients from the local cardiac surgery database collected from 2010 to 2019. BMI (weight [kg]/height² [m²]) was calculated for all patients which were then assigned into groups (normal [BMI 18.5–24.9], overweight [BMI 25–29.9], and obese [BMI ≥ 30]). Baseline characteristics were assessed, including a history of cardiovascular risk factors and biochemistry. The prevalence of the MI type (as either STEMI or NSTEMI) was calculated for each BMI group. The MI type was correlated against BMI groups adjusted for cardiovascular risk factors and biochemical parameters associated with the metabolic syndrome including low-density lipoprotein (LDL), triglycerides, and fasting blood glucose.

Results: NSTEMI was more prevalent across all BMI groups compared to STEMI. NSTEMI was more prevalent (STEMI less prevalent) in both the obese and overweight groups when compared to the normal BMI group (82.4% vs 71.1%, P = 0.001, and 79.8% vs 71.1%, P = 0.008 respectively). There was no significant difference in the prevalence of NSTEMI or STEMI between obese and overweight BMI classes (82.4% vs 79.8%, P = 0.34). Further analysis of the type of MI with ordinal logistic regression revealed a reduced likelihood of STEMI with increasing BMI class (OR: 0.57 ± 0.16, 95% confidence interval 0.33–0.97, P = 0.042) and is statistically significant when adjusted for above co-variates.

Conclusion: This studied showed that NSTEMI was more prevalent relative to STEMI amongst high BMI patients. Increasing BMI was associated with reduced likelihood of STEMI. Although these findings are in contrast with our hypothesis, it highlights the impact of obesity on MI presentations. This may have clinical and/or practical implications on the management of MI in the obese population and further studies are warranted in this context.