# Risk factors when considering heart transplants with donors aged 45 or above: Development of a Novel Mortality Risk Score using UNOS data

## TL;DR

This study identifies risk factors for mortality in heart transplant recipients using donors aged 45 or older and creates a new risk score to help guide transplant decisions.

## Contribution

A novel mortality risk score for heart transplants using donors aged ≥45, based on UNOS data.

## Key findings

- 1-, 5-, and 10-year survival rates were 87.0%, 73.3%, and 53.5% for transplants using donors aged ≥45.
- Key risk factors included ischemic time ≥4 hours, CMV-positive donor status, and recipient factors like age >55 and diabetes.
- The risk score model had moderate discrimination with a C-statistic of 0.58.

## Abstract

Current International Society for Heart and Lung Transplantation guidelines support the use of donor hearts aged ≥45 if significant coronary artery disease is excluded and ischemic time remains <4 hours. This study aimed to identify additional risk factors affecting patient survival and develop a risk score for recipients of older donor hearts.

We performed a retrospective cohort study of adult heart transplants using donors aged ≥45 from January 2000 to June 2024, using United Network for Organ Sharing data. Multivariable Cox regression identified risk factors for mortality, and the most significant variables were used to construct a risk score.

Of 58,859 adult heart transplants, 9,843 (16.7%) involved donors aged ≥45. Recipient median age was 58 years (interquartile range, 51-64). One-, 5-, and 10-year patient survival rates were 87.0%, 73.3%, and 53.5%, respectively. Statistically significant risk factors included ischemic time ≥4 hours (HR = 1.11), cytomegalovirus (CMV)-positive donor status (hazard ratio [HR] = 1.11), donor cigarette use (HR = 1.10) and recipient factors: age >55 (HR = 1.37), Black race (HR = 1.19), obesity (HR = 1.20), diabetes (HR = 1.27), pretransplant dialysis (HR = 1.44), pretransplant mechanical ventilator use (HR = 1.37), and prior cardiac surgery (HR = 1.28). Model discrimination was moderate with C-statistics of 0.58.

When considering heart transplants with donors aged ≥45, we should screen for ischemic time ≥4 hours, CMV-positive donor, donor cigarette use, and the following recipient factors: age >55, Black race, obesity, diabetes, pretransplant dialysis or mechanical ventilation, and prior cardiac surgery.