Predicting Survival Outcomes in Fontan Patients Post-Heart Transplant

The Model for End-Stage Liver Disease Excluding INR (MELD-XI) score can predict survival outcomes following heart transplant in patients with Fontan physiology. This is the lead finding in a study published in The Journal of Thoracic and Cardiovascular Surgery.1

The Fontan operation, also known as total cavopulmonary anastomosis, is a palliative procedure indicated for patients with a univentricular heart. It has become a standard intervention for patients with one functioning or anatomic ventricle.

Over time, this malformation can lead to a number of complications, explains Shahnawaz Amdani, MD, a pediatric cardiologist at Cleveland Clinic Children’s and first author of the study. “The absence of a ventricular pump can lead to multi-organ dysfunction, with effects particularly to the liver and kidneys,” he says.

While heart transplant is often recommended for these patients, end-organ dysfunction can lead to poorer survival outcomes in this patient population.

Assessing liver health preoperatively is important, Dr. Amdani stresses. He notes that patients with advanced liver disease can develop challenging post-operative complications such as dangerously low blood pressure and increased postoperative bleeding.

“We do conduct liver biopsies and ultrasounds or magnetic resonance imaging to determine the severity of the liver damage, but almost every Fontan patient has some degree of liver damage, making it really difficult to assess who is truly at an increased risk for worse outcomes post-heart transplant,” he says.

Dr. Amdani and his collaborators set out to take a closer look at factors associated with morbidity and mortality in Fontan patients, specifically those undergoing a heart transplant. In the largest investigation of its kind, the team leveraged data from the Pediatric Heart Transplant Society database and examined patients listed for transplant between January 2005 and December 2018, totaling 6,518 patient listings. Of this dataset, 783 of these listings were Fontan patients; and 565 (72%) had undergone transplant.

They calculated the MELD-XI score, which provides a simultaneous assessment of liver and kidney function at the time of heart transplant listing and at the time of transplantation, by creating two cohorts: a high MELD-XI score cohort (MELD-XI score ≥ 11.5), representing those in the with scores in the75th percentile, and a low score cohort (MELD-XI score < 11.5).

The team also examined the impact of changes in the MELD-XI score while on the waitlist and its effect on post-transplant survival by creating a four-category system that reflected a patient’s score at the time of listing and transplant: low/low, low/high, high/low and high/high.

Key findings: At a glance

After a multivariable analysis was conducted, the study yielded the following results:

• The MELD-XI score provided an accurate assessment of illness acuity; Fontan patients with higher scores require more support at the time of listing and at transplant.
• Fontan patients in the high MELD-XI score cohort had worse one and five-year post-heart transplant outcomes, compared to those in the low MELD-XI score cohort.
• Patients with high MELD-XI scores at both listing and transplant (the high/high cohort) are more likely to be among the sickest and have worse outcomes.

Clinical implications

The MELD-XI score provides clinicians with an opportunity to collect and trend an objective score that accurately identifies Fontan patients at increased risk for post-heart transplant mortality.

Dr. Amdani says that the MELD-XI score uniquely captures derangements in liver and kidney function, two organs critically affected in those with failing Fontan physiology. He also stresses that this calculation is a real-time assessment and, therefore, subject to change day-to-day.

Concluding, he notes, “We hope that these findings will help facilitate important conversations with Fontan patients and their families about post-heart transplant outcomes, allowing clinicians to aid in decision-making and set expectations for postoperative outcomes.”

Reference

1. Amdani S, Simpson KE, Thrush P, Shih R, Simmonds J, Knecht K, Mogul DB, Hurley K, Koehl D, Cantor R, Naftel D, Kirklin JK, Daly KP. Hepatorenal dysfunction assessment with the Model for End-Stage Liver Disease Excluding INR score predicts worse survival after heart transplant in pediatric Fontan patients. J Thorac Cardiovasc Surg. 2021 Feb 18:S0022-5223(21)00262-2. doi: 10.1016/j.jtcvs.2021.02.014. Epub ahead of print. PMID: 33745714.