Donor predicted heart mass as predictor of primary graft dysfunction

Background: Concern over the hazards associated with undersized donor hearts has impeded the utilization of otherwise viable allografts for transplantation. Previous studies have indicated predicted heart mass (PHM) may provide better size matching in cardiac transplantation than total body weight (TBW). We investigated whether size-matching donor hearts by PHM is a better predictor of primary graft dysfunction (PGD) than matching by TBW.

Methods: Records of consecutive adult cardiac transplants performed between 2012 and 2016 at a single-center academic hospital were reviewed. We compared patients implanted with hearts undersized by ≥30% with those implanted with donor hearts matched for size (within 30%), and performed the analysis both for undersizing by PHM and for undersizing by TBW. The primary outcome was moderate/severe PGD within 24 hours, according to the 2014 International Society for Heart and Lung Transplantation consensus. Secondary outcome was 1-year survival.

Results: Of 253 patients, 21 (8%) and 30 (12%) received hearts undersized by TBW and PHM, respectively. The overall rate of moderate/severe PGD was 13% (33 patients). PGD was associated with undersizing if performed by PHM (p = 0.007), but not if performed by TBW (p = 0.49). One-year survival was not different between groups (log-rank, p > 0.8). Multivariate analysis confirmed that undersizing donor hearts by PHM, but not by TBW, was predictive of moderate/severe PGD (OR 3.3, 95% CI 1.3 to 8.6).

Conclusions: Undersized donor hearts by ≥30% by PHM may increase rates of PGD after transplantation, confirming that PHM provides more clinically appropriate size matching than TBW. Better size matching may ultimately allow for expanding the donor pool.