Obesity and Acute Kidney Injury in Patients with ST-Elevation Myocardial Infarction

Background: Data on the association between obesity and acute kidney injury (AKI) in patients with ST-elevation myocardial infarction (STEMI) are sparse and inconclusive. We aimed to evaluate the association between obesity and AKI and the outcome in these patients. Methods: A retrospective observational study of 3979 STEMI patients undergoing percutaneous coronary intervention (PCI) was performed at a single center. Patients with and without AKI were compared. Patients were also divided into three categories according to BMI, and these were compared. All-cause mortality was determined at 30 days and over a median period of 7.0 years. Results: The incidence of AKI was similar in all BMI categories. There was no association between BMI categories and AKI (p = 0.089). The Spearman correlation coefficient between BMI categories and AKI showed no correlation (r = -0.005; p = 0.75). More AKI patients died within 30 days and in the long term [137 (18.5%) and 283 (38.1%) patients in the AKI group died compared to 118 (3.6%) and 767 (23.1%) in the non-AKI group; p < 0.0001]. AKI was harmful in all BMI categories (p < 0.0001) and was associated with more than a 2.5-fold and a 1.5-fold multivariable-adjusted 30-day and long-term mortality risk, respectively (aOR 2.59; 95% CI 1.84-3.64; p < 0.0001, aHR 1.54; 95% CI 1.32-1.80; p < 0.0001). BMI categories were not associated with 30-day mortality (p = 0.26) but were associated with long-term mortality (p < 0.0001). Overweight and obese patients had an approximately 25% lower long-term multivariable-adjusted risk of death than normal-weight patients. In patients with AKI, BMI was only associated with long-term risk (p = 0.022). Obesity had an additional beneficial effect in these patients, and only patients with obesity, but not overweight patients, had a lower multivariable adjusted long-term mortality risk than normal-weight patients (aHR 062; 95% CI 0.446-0.88 p = 0.007). Conclusions: In patients who experienced AKI, obesity had an additional positive modifying effect. Our data suggest that the incidence of AKI in STEMI patients is not BMI-dependent.