Prevalence of obesity and associated long-term cardiovascular risk in a modern Swedish population with acute myocardial infarction with and without diabetes

Background Obesity is associated with a high risk of cardiovascular disease (CVD) and mortality where such risk increases with increasing body mass index (BMI). In a population with established CVD, less is known about obesity and diabetes as coexisting comorbidities and their impact on prognosis. Purpose To explore the burden of obesity in a national cohort with acute myocardial infarction (AMI) and the impact on outcome in patients with and without diabetes. Methods We included all patients with AMI undergoing coronary angiography in Sweden in 2010-2021. BMI was collected at the time of angiography and classified 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). Data on baseline characteristics and outcome as major cardiovascular events (MACE; first of death, myocardial infarction [MI], stroke or heart failure) and death was obtained from national registries. Cox proportional survival analysis adjusted for important clinical variables such as age, comorbidities, indication and angiographic findings assessed outcomes (reference=normal BMI without diabetes). Results Of 124 360 patients, 21% (n=25 907) had diabetes, 68% were men and 41% suffered a ST-elevation MI. Obesity was much more common in patients with diabetes, 37% vs. 20%, present throughout all classes of obesity. Patients with class 3 obesity were younger than those with normal BMI regardless of diabetes status. Comorbidities such as hypertension, hyperlipidaemia and heart failure were more prevalent among those with diabetes. Further, the presence of comorbidities was increasing with obesity grade irrespective of diabetes status. Analysis of absolute event rate revealed a high one-year MACE rate in patients with diabetes compared to those without, 27% vs. 17%. During a mean follow-up of 2175 days, across all obesity classes, diabetes was associated with an increased adjusted risk of MACE (Figure). The highest risk was seen in those with class 3 obesity and diabetes (HR 1.91; 95% CI 1.73-2.10 vs. 1.29; 1.16-1.45 in those without diabetes). Patients with class 3 obesity without diabetes had a similar risk of future MACE and mortality as an individual with diabetes and normal BMI (Figure). Conclusion In patients with coronary artery disease, obesity is twice as common if diabetes is present. A consistently higher risk of adverse outcome was seen in individuals with diabetes than those without. After adjustments for age and comorbidities, obesity remained as an important risk factor for future cardiovascular events, highest in patients with diabetes and severe obesity. Patients without diabetes but with class 3 obesity had a similar risk of future MACE and mortality as an individual with diabetes and normal BMI. This strengthens the importance of cardioprotective secondary treatment in these patients, especially diabetes patients with obesity.