Obesity and diabetes, two important modifiable prognostic risk factors after myocardial infarction in women

Background Obesity is associated with cardiovascular disease (CVD) and mortality. In women with established CVD, less is known about prevalence of obesity and diabetes as concomitant comorbidities and their impact on prognosis. Purpose To analyse the burden of obesity in women in a modern cohort with acute myocardial infarction (AMI) and the associated risk of major adverse cardiovascular events (MACE) stratified by diabetes status. Methods We included all women with AMI investigated with coronary angiography in Sweden between 2010-2021. Body mass index (BMI) at admission was grouped according to the WHO classification into low BMI (<18.5 kg/m2), normal BMI (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), class 1 obesity (30.0-34.9 kg/m2), class 2 obesity (35.0-39.9 kg/m2) and class 3 obesity (≥40.0 kg/m2). Information on baseline characteristics and long-term adverse events was collected from national Swedish registries. Multivariate Cox proportional survival analyses were performed to assess outcomes where normal BMI without diabetes served as a reference. Results Of 39 881 women included, 21.9% (n=8721) had diabetes, 38.2% suffered a ST-elevation myocardial infarction and mean age was 72.0 years (SD 11.4). Obesity was twice as common if diabetes was present, 40.1% vs. 20.8%. Women with class 3 obesity were substantially younger than those with normal BMI regardless of diabetes status (66.7 vs. 74.0 in women with diabetes, and 62.3 vs. 72.7 years in those without). Previous diagnoses of hypertension and hyperlipidaemia were more common among patients with diabetes (76.8% vs. 53.1%, and 49.4% vs. 23.5% respectively) and such prevalence increased with obesity classes, regardless of diabetes status. On the contrary, smoking and previous myocardial infarction (MI) were more common in those with normal BMI, although prevalence of the aforementioned was twice as high if diabetes was present. Women with diabetes had a higher absolute one-year MACE rate (first of all-cause death, MI, stroke, or heart failure) compared to those without, 30.9% vs. 20.2%. After adjustments, diabetes increased the risk of future MACE regardless of obesity but was even higher if more severe obesity was present, associated Hazard Ratio (HR) with 95% Confidence Interval (CI) for diabetes and class 3 obesity 1.73 (1.50-2.00) vs. 1.25 (1.07-1.47) in those with only class 3 obesity and no diabetes. Corresponding figures for all-cause death was 1.84 (1.52-2.23) vs. 1.26 (1.00-1.59). Conclusion In women with myocardial infarction, where around one fifth of the women suffer from diabetes, obesity is common and present in 40% of the patients with diabetes and 20% in those without diabetes. The risk of future events and mortality was especially increased if diabetes or class 3 obesity was present. This strengthens the importance of a cardioprotective secondary preventive approach in women with obesity, diabetes and established cardiovascular disease.