Background: Obesity is a known cardiovascular risk factor and its prevalence in the general population has increased during the last decades, especially of severe obesity. Aim of the present study was to analyse prevalence rates of severe obesity (body mass index (BMI)≥40 kg/m²) in patients with ST-elevation myocardial infarctions (STEMI) between 2006 and 2022 and its association to age, other cardiovascular risk factors and in-hospital- and long-term-outcome rates.

Methods: All patients admitted with STEMI between 2006 and March 2022 entered analysis. Patients were assigned to a control group (BMI≤35 kg/m²), a second control group (obesity grade 2 (BMI 35-39.9 kg/m²)) and the study group with severe obesity (BMI≥40 kg/m²).

Results: Of a total of 11740 patients 269 patients (2.3%) had severe obesity with a mean weight of 128.9±18 kg, while 589 patients (5.0%) had obesity grade 2. Patients with severe obesity were on average 6.4 years younger compared to controls (57.7±11.5 yrs. vs. 64.1±13.1 yrs., p<0.01) and more likely to be female (37.2% vs. 26.8 %, p<0.01). Prevalence rates of severe obesity were especially high in the young (<45 yrs): women: 9.3%, men 3.0%, p<0.01. During the study period the proportion of severe obesity increased from 1.9% (2006-13) to 2.9% (2014-22), p<0.01, again more prominently in women: 2.5 % to 3.9% (p=0.02) compared to men: 1.7% to 2.5% (p<0.01). The increase of severe obesity over time was highest in young STEMI-patients: <45 yrs. : 2.4% (2006-2013) to  6.2% (2014-2020), p<0.01; 45-54 yrs: 2.8% to 4.6%, p=0.02; ≥55 yrs.: 1.6 to 1.9%, p=0.45. This observation could be confirmed in a multivariate model, with the most prominent increase of severe obesity in young women (table). While there was no association between severe obesity and hyperlipidemia (severe obesity: LDL-cholesterol 120.9±44 mg/dl vs. 121.5±57 mg/dl in controls, p=0.91) it was associated with higher rates of diabetes mellitus (45.5% vs. 18.8%, p<0.01). Patients with severe obesity showed similar rates of multivessel disease (61.6% vs. 63.5%, p=0.51) and successful primary percutaneous coronary intervention (TIMI 2/3 post PCI: 96.2% vs. 95.1%, p=0.44). In an adjusted analysis severe obesity was associated with similar in-hospital-mortality-rates (OR 0.98, 95% CI 0.6-1.6, p=0.94); however, a trend for a higher 1-year-mortality (OR 1.49, 95% CI 0.98-2.2, p=0.065) and a significantly higher 5-year-mortality (OR 1.82, 95% CI 1.17-1.82, p<0.01) could be observed.

Table: Likelihood of severe obesity 2014-2022 compared to 2006-2013

Conclusions: During the study period rates of severe obesity in STEMI-patients significantly increased especially in the young and in women, which may lead to overall higher infarction rates for these population groups in the future. Severe obesity was associated with a young age at time of the index event and while it did not negatively impact interventional success-rates it was associated with worse long-term outcome.