Microaxial Left Ventricular Assist Device Versus Intraaortic Balloon Pump as a Bridge to Transplant

Heart transplantation (HTx) candidates supported by Impella (Abiomed, Danvers, MA) or intraaortic balloon pump (IABP), who demonstrate evidence of cardiogenic shock, may qualify for waitlist status 2 without exception under the new donor heart allocation system. However limited data comparing Impella versus IABP as a bridge to HTx exist.

The United Network for Organ Sharing database was queried for adults listed and/or transplanted between January 2014 and February 2020. Temporal trends regarding Impella and IABP use were analyzed using the Royston trend test and χ² test. Waitlist mortality was examined using Fine-Gray competing risks analysis. Post-HTx 180-day survival was analyzed using the Kaplan-Meier method and Cox proportional hazards models.

Impella use increased from 0.2% in 2014 to 2.6% in 2020 (P < .01) and from 0.4% to 2.2% (P < .01) under the new allocation system. IABP use increased from 4.9% in 2014 to 27.6% in 2020 (P < .01) and from 6.7% to 26.6% (P < .01) under the new allocation system. Post-HTx survival was similar between groups (adjusted hazard ratio, 0.82; 95% CI, 0.38-1.78) despite more preoperative ventilation (3.6% vs 1.1%, P = .01) and higher model for end-stage liver disease excluding international normalized ratio scores (12.4 vs 9.5, P < .01) among Impella-supported recipients. Under the new system Impella-supported candidates were at higher risk of waitlist delisting compared with IABP-supported candidates (subhazard ratio, 2.42; 95% CI, 1.19-4.92).

Post-HTx survival is comparable between Impella-supported and IABP-supported recipients despite worse preoperative profiles among Impella-supported recipients. Higher risk of waitlist delisting among Impella-supported candidates under the new allocation system requires close attention.