Assessing donor-recipient size metrics for heart transplant outcomes: UNOS database analysis

Area of Science:

• Cardiology
• Transplant Surgery
• Medical Statistics

Background:

• Donor-recipient size matching is crucial for cardiac transplant success.
• Current size-match metrics lack universal acceptance and predictive validation across different heart failure etiologies.
• The impact of restrictive versus non-restrictive heart failure pathology on size-match metric efficacy is not well understood.

Purpose of the Study:

• To evaluate the predictive performance of common donor-recipient size-match metrics for cardiac transplant outcomes.
• To determine if recipient heart failure etiology (restrictive vs. non-restrictive) influences the association between size-match metrics and survival.
• To identify the most reliable size-match metric for predicting survival in diverse cardiac transplant populations.

Main Methods:

• Utilized the UNOS registry data from 2000-2017 for primary isolated heart transplants.
• Calculated donor-recipient ratios for multiple size metrics including height, predicted heart mass (PHM), ideal body weight (IBW), body mass index (BMI), weight, and body surface area (BSA).
• Employed continuous, nonlinear analysis to assess the association between size metrics and patient survival, stratifying by restrictive and non-restrictive heart failure pathology.

Main Results:

• Height, PHM, IBW, and BMI ratios were significantly associated with survival (p < .001).
• Weight and BSA ratios did not show significant association with survival.
• Body mass index (BMI) ratio was the only metric to retain significance across both restrictive (p = .051) and non-restrictive (p = .003) recipient groups.
• Recipients with restrictive etiology exhibited increased mortality risk with both low and high BMI ratios, indicating differential tolerance to size mismatch.

Conclusions:

• Body mass index (BMI) ratio is a significant predictor of survival in cardiac transplantation, particularly in patients with restrictive heart failure.
• The efficacy of various size-match metrics differs based on the recipient's underlying heart failure etiology.
• Understanding how restrictive and non-restrictive heart failure impacts size mismatch tolerance is critical for optimizing cardiac transplant outcomes.