Effect of Body Mass Index in Patients With Cardiogenic Shock Requiring Microaxial Flow Pump.

Background: The impact of obesity on mortality in patients with cardiogenic shock (CS) requiring microaxial flow pumps (mAFP) remains undetermined.

Objectives: This study investigated the effect of body mass index (BMI) on mortality in CS patients treated with mAFP.

Methods: Data from 3,636 consecutive CS patients treated with Impella mAFP in the J-PVAD (Japanese Registry for Percutaneous Ventricular Assist Device) nationwide prospective registry in Japan between February 2020 and December 2022 were analyzed. Patients were stratified into 5 BMI categories: underweight (<18.5 kg/m), normal weight (18.5-22.9 kg/m), overweight (23.0-24.9 kg/m), obesity (25.0-29.9 kg/m), and severe obesity (≥30.0 kg/m). Multivariate Cox regression analysis assessed the relationship between BMI and 30-day mortality.

Results: Crude 30-day mortality increased incrementally with higher BMI categories. Adjusted HRs for 30-day mortality (normal weight as reference) were 0.71 (95% CI [CI]: 0.56-0.90; P = 0.005) for underweight, 1.03 (95% CI: 0.88-1.21; P = 0.681) for overweight, 1.37 (95% CI: 1.19-1.57; P < 0.001) for obesity, and 2.00 (95% CI: 1.66-2.41; P < 0.001) for severe obesity. Patients in the underweight and severe obesity groups experienced a higher incidence of bleeding after percutaneous coronary intervention under mAFP, whereas hemolysis increased with higher BMI categories. Bleeding and hemolysis were associated with mortality only in patients who were underweight.

Conclusions: Higher BMI was associated with increased mortality in CS patients treated with mAFP. Although patients who were underweight demonstrated overall favorable survival outcomes, bleeding and hemolysis contributed to mortality in this group. Further research is needed to explore whether a BMI-based approach can improve clinical outcomes. (Japanese registry for Percutaneous Ventricular Assist Device; UMIN000033603).