Progression to Transplant Under the New Heart Allocation System: The Society of Thoracic Surgeons Intermacs Database

Background: Under the new heart allocation policy patients needing durable left ventricular assist devices receive lower priority on the transplant list. We sought to identify predictors of successful heart transplant after durable device implant as a means to inform patient care in the current era.

Methods: All patients (N = 25,164) undergoing primary durable left ventricular device implant in The Society of Thoracic Surgeons Intermacs database (2010-2019) were evaluated. Patients identified as bridge to transplant (BTT; n = 5242) or bridge to candidacy (n = 6248) were analyzed with the endpoint of transplant before (n = 10,588) and after (n = 902) the change in the heart allocation system on October 18, 2018. Multivariable hazard modeling was used to assess risk-adjusted time to event associations.

Results: Of 11,490 patients, 45.5% progressed to transplant (BTT, 53.0%; bridge to candidacy, 36.6%), most by 14 months after left ventricular assist device implant. Under the new allocation system progression to transplant was significantly lower at 14 months (18.6% vs 34.8%, P < .001). Factors associated with successful BTT before the allocation change included BTT status, white race, and married. Under the new allocation system BTT status (hazard ratio, 1.79; 95% confidence interval, 1.19-2.69; P < .0054) remained a positive predictor, whereas blood type O (hazard ratio, 0.43; 95% confidence interval, 0.28-0.65; P < .0001) remained a negative predictor.

Conclusions: Despite having priority in the previous allocation system, less than half of BTT and bridge to candidacy patients progressed to transplant. Under the current system these numbers are further reduced. Heart teams should consider the implications of longer wait times for a durable left ventricular assist device when determining the optimal bridging strategy.