Size matching in combined heart-lung transplant: An undersized predicted heart mass is associated with increased mortality

BACKGROUND: Numerous studies have analyzed the consequences of donor-recipient organ size mismatch within both heart and lung transplantation. However, there is very little data on size matching in combined heart-lung transplantation (HLTx). We reviewed how donor/recipient predicted total lung capacity (pTLC), predicted heart mass (pHM), weight, and height ratios affect HLTx survival and graft rejection outcome. METHODS: We performed a retrospective analysis on adult HLTx patients using the UNOS database. Overall survival at 1- and 5-years, as well as 5-years bronchiolitis obliterans syndrome (BOS) and coronary artery vasculopathy (CAV) development, were the outcomes of interest. Each sizing modality was split into 5 groups for survival analysis and 3 groups for graft rejection analysis based on an approximately equal size-matched reference group. RESULTS: In total, 747 patients were analyzed in our study. Of the 4 sizing modalities, only pHM ratio had a significant difference in acute and long-term survival. In particular, a severely undersized pHMr of < 83% was associated with an increased risk of mortality compared to an approximately equally sized match (1-year: HR=1.95, 95% CI=1.30-2.91, p = 0.001; 5-year: HR = 1.47, 95% CI = 1.05-2.06, p = 0.027). No sizing metric was predictive of BOS or CAV development. CONCLUSION: Our analysis supports the use of pHM ratio for size matching in HLTx. Based on our results, a donor/recipient pHM ratio of > 83% should be achieved to minimize mortality risk associated with sizing mismatch. (C) 2022 International Society for Heart and Lung Transplantation. All rights reserved.

Automated summary

This study retrospectively analyzed the impact of donor-recipient organ size matching on survival and graft rejection outcomes in combined heart-lung transplantation. The results showed that matching based on predicted heart mass ratio (pHM ratio) can reduce the risk of mortality associated with organ size mismatch.