Impacts of Hospital Volume and Patient-Hospital Distances on Outcomes of Older Adults Receiving Percutaneous Microaxial Ventricular Assist Devices for Cardiogenic Shock.

Background: Percutaneous microaxial ventricular assist devices (pVAD) have the potential to reduce mortality of patients with cardiogenic shock (CS). However, the association between the distribution of pVAD-performing centers and outcomes of CS has not been explored. Methods: This observational study included Medicare fee-for-service beneficiaries aged 65-99 years treated with pVAD for CS from 2016 to 2020 and examined the associations between patient outcomes and two exposure variables: hospitals' procedure volumes of pVAD and patient-hospital distances (in quintiles [Qn]). We developed Cox proportional hazard regression for 180-day mortality and heart failure (HF) readmission rates and multivariable logistic regression for in-hospital outcomes, adjusting for patient demographics, comorbidities, concomitant treatments, and hospital characteristics, including CS volume, teaching status, and the ability to perform extracorporeal membrane oxygenation. Results: A total of 6,637 patients with CS underwent pVAD at 1,041 hospitals, with the annualized hospital volume ranging widely from 0.3 to 55.6 cases/year. Patients treated at higher-volume centers experienced lower 180-day mortality compared with patients treated at lower-volume centers (Qn1=reference; Qn2: adjusted hazard ratio [aHR], 0.88; 95% confidence interval [CI], 0.79-0.97; Qn3: aHR, 0.88; 95% CI, 0.79-0.98; Qn4: aHR, 0.88; 95% CI, 0.78-0.99; Qn5: aHR, 0.84; 95% CI, 0.74-0.95; p-for-trend, 0.026), while we found no evidence that patient-hospital distances were associated with mortality (Qn1=reference; Qn2: adjusted hazard ratio [aHR], 0.99; 95% confidence interval [CI], 0.89-1.09; Qn3: aHR, 0.94; 95% CI, 0.85-1.04; Qn4: aHR, 1.01; 95% CI, 0.92-1.11; Qn5: aHR, 0.91; 95% CI, 0.82-1.01; p-for-trend, 0.160). We found no evidence that the hospital volume and patient-hospital distances were associated with in-hospital bleeding, intracranial hemorrhage, or renal replacement therapy initiation. Conclusions: Hospital volume was more strongly associated with mortality than patient-hospital distances, suggesting that rational distribution of pVAD-performing centers while ensuring adequate procedure volumes may optimize patient mortality.