Sex-specific obesity paradox and type 2 myocardial infarction in acute ischemic stroke (AIS) patients

Background and aims Obesity is usually linked to negative outcomes in many diseases; however, some acute critical conditions exhibit a phenomenon known as the obesity paradox. This investigation assessed sex-specific differences in type 2 myocardial infarction (T2MI), a condition caused by an imbalance between oxygen supply and demand in the myocardium and unrelated to atherosclerotic plaque rupture. Additionally, the study explored the implications of body mass index (BMI) in patients with acute ischemic stroke (AIS). Methods AIS patients were consecutively enrolled at Jiading District Central Hospital affiliated Shanghai University of Medicine & Health Sciences, from October 1, 2017, to December 31, 2023. Participants were divided into four groups based on their BMI: underweight group, normal weight group, overweight group, and obesity group. The primary outcome of the study was the incidence of T2MI. We employed Cox regression analysis and Kaplan–Meier curves to examine the relationship between BMI and the occurrence of T2MI. Additionally, we performed a restricted cubic spline (RCS) analysis to evaluate the linearity of this relationship, utilizing an iterative algorithm to pinpoint inflection points. The subgroup forest plot displays how the four BMI groups vary across different layers. Results The incidence of T2MI was 4.43%(131/2995) in AIS patients. After adjusting for potential confounding variables, the risk of T2MI was higher in the normal-weight group (HR, 2.11; 95% CI, 1.36–3.26; p < 0.001) compared to the obese group. In female patients, the risk of T2MI was higher in both the normal-weight group (HR, 3.47; 95% CI, 1.64–7.36; P = 0.001) and the underweight group (HR, 4.06; 95% CI, 1.44–11.44; P = 0.008) compared to the obese group; however, no such association was found in male patients. Furthermore, the RCS analysis confirmed a linear correlation between BMI and the risk of T2MI. Conclusions The association between BMI and T2MI in AIS patients varied between genders. Obese female AIS patients had a lower risk of T2MI, a trend that was not mirrored in their male counterparts. These findings underscore the importance of considering sex-specific factors in understanding the complex relationship between obesity and T2MI in patients with AIS.