Cardiogenic Shock: Outcome Patterns Across the Body Mass Spectrum and Renal Vulnerability

Background: The relationship between body mass index (BMI) and acute kidney injury (AKI) and mortality in infarction-related cardiogenic shock (CS) remains uncertain. We investigated the association between BMI and renal and short-term clinical outcomes in patients with infarction-related CS. Methods: In this retrospective single-center cohort study, 369 consecutive patients with infarction-related cardiogenic shock were included. Body mass index (BMI) was analyzed as the exposure variable and modeled both continuously and according to World Health Organization categories. Acute kidney injury (AKI) within 96 hours, defined according to KDIGO creatinine-based criteria, and in-hospital mortality were the primary outcomes; renal replacement therapy (RRT) was a secondary outcome. Associations were assessed using multivariable logistic regression adjusted for prespecified confounders, including age, sex, diabetes mellitus, chronic kidney disease, and baseline estimated glomerular filtration rate. Nonlinear relationships were explored using restricted cubic spline analyses. Results: AKI occurred in 158 patients (42.8%). Higher BMI, modeled as a continuous variable, was associated with an increased risk of AKI (adjusted OR 1.34 per 5 kg/m²; 95% CI, 1.06–1.69; p = 0.012). RRT was more frequently required in patients with obesity than in those with normal weight (18.5% vs. 8.6%; p = 0.018). When analyzed categorically, overweight (BMI 25.0–29.9 kg/m²) was associated with lower in-hospital mortality compared with normal weight (adjusted OR 0.66; 95% CI, 0.45–0.95; p = 0.028), whereas obesity was not independently associated with mortality. Nonlinear modeling suggested a U-shaped relationship between BMI and both AKI and in-hospital mortality, with the lowest estimated risk at intermediate BMI levels. Conclusions: In patients with infarction-related cardiogenic shock, BMI was associated with both renal outcomes and in-hospital mortality. Higher BMI was linked to increased renal vulnerability, whereas overweight was associated with lower mortality. These findings should be interpreted cautiously given the observational design and the potential for residual confounding and reverse causation, particularly at lower BMI levels.