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

## TL;DR

In female stroke patients, being obese is linked to a lower risk of a specific type of heart damage compared to being normal or underweight, but this pattern does not hold for males.

## Contribution

The study reveals a sex-specific obesity paradox in acute ischemic stroke patients regarding type 2 myocardial infarction risk.

## Key findings

- Obese female AIS patients had a lower risk of T2MI compared to normal-weight and underweight females.
- No significant association between BMI and T2MI was found in male AIS patients.
- The relationship between BMI and T2MI risk was linear, as confirmed by restricted cubic spline analysis.

## Abstract

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).

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.

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.

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.

The online version contains supplementary material available at 10.1186/s13293-026-00823-x.

In AIS patients, obese individuals, especially females, showed a significantly lower risk of experiencing T2MI compared to their non-obese counterparts. After adjusting for potential confounding variables, we consistently observed that normal-weight patients were more likely to experience T2MI than those classified as obese. Normal-weight and underweight females had a higher risk of T2MI compared to obese females, but this difference was not seen in males. The study showed that an obesity paradox exists in female patients with AIS regarding the incidence of T2MI. This highlights the importance of considering gender-specific factors to understand the complex relationship between obesity and T2MI in AIS patients.

The online version contains supplementary material available at 10.1186/s13293-026-00823-x.

In AIS patients, females are at higher risk for T2MI than males.A sex-specific obesity paradox relates to the occurrence of T2MI in AIS patients. Female patients with normal-weight or underweight had a higher risk of T2MI than obese female patients, but no such difference was found among male patients.

In AIS patients, females are at higher risk for T2MI than males.

A sex-specific obesity paradox relates to the occurrence of T2MI in AIS patients. Female patients with normal-weight or underweight had a higher risk of T2MI than obese female patients, but no such difference was found among male patients.

The online version contains supplementary material available at 10.1186/s13293-026-00823-x.