Overweight predisposes to microvascular obstruction: insights from the TATORT-NSTEMI trial

Microvascular obstruction (MVO) is a phenomenon associated with worse outcome after acute myocardial infarction. While some studies suggested a benefit of an increased body mass index (BMI) in terms of MVO occurrence in ST-elevation myocardial infarction (STEMI), there are currently no data available on the influence of overweight on the development of MVO in Non-STEMI (NSTEMI). Thus, the aim of this study was to assess the association between MVO and BMI in NSTEMI patients. This study investigated a sub-cohort of the TATORT-NSTEMI trial. Overall, 354 patients were included with a median age of 68 years (25% women). Cardiac magnetic resonance imaging (CMR) was performed within four days after the index event. MVO was defined as hypointense core within the infarcted area in late-enhancement sequences. MVO occurred in 97 patients (27%) and patients with MVO had a significantly higher BMI (28.4 kg/m², interquartile range (IQR) 26.1-31.1 vs. 27.3 kg/m², IQR 24.8-30.3, p = 0.024). Dichotomized at 25.6 kg/m² (Youden-index), patients with a BMI above that threshold showed significantly more often MVO (33% vs. 15%, p < 0.001). In logistic regression analysis, BMI > 25.6 kg/m² was a significant predictor of MVO, independent of traditional cardiovascular risk factors. In the current study, an increased BMI has been associated with MVO after NSTEMI. Further, overweight and especially a BMI above 25.6 kg/m² were independent predictors of MVO in these patients, challenging the so-called "obesity paradox". Lastly, further research on the connection between body weight and microvascular damage in myocardial infarction is needed.