Abstract 4136712: Fontan-specific morbidities impact on heart transplant outcomes: a multicenter study

Introduction: Fontan circulatory failure (FCF) is associated with poor long-term survival. The impact of Fontan-specific morbidities on outcomes in those evaluated for heart transplant (HT) are not well understood. Hypothesis: FCF-specific morbidities, their degree of severity, and the accumulation of morbidities are associated with mortality in individuals undergoing HT. Methods: This 20 center, retrospective cohort study of individuals with FCF from 2008-2023 collected data on FCF-specific morbidities, waitlist (WL), and post-HT outcomes. Each unique FCF morbidity was defined with graded severities (absent, mild, moderate, severe, and life-threatening) via a prior effort. The primary outcome was survival from WL to 1-year post-HT. Appropriate 2-group statistics and multivariable logistic regression compared surviving with those who died. Receiver operating characteristic curve determined the most discriminating value of total cumulative morbidities on mortality. Results: Of the 340 patients included, 51(15%) died between WL and 1 year post-HT. On univariate analysis, 7 of 27 FCF morbidities were associated with the mortality (p < 0.2) including: anatomic Fontan pathway obstruction, clinical hypoxia, chronic pleural effusions, sleep apnea, portal variceal disease, acute kidney injury within 1 year prior to WL, and mental health disorders. On multivariable analysis, only clinical hypoxia and portal variceal disease emerged as independent risk factor for mortality (adjusted odds ratio [aOR]: 2.48, p = 0.03 and aOR 2.74 P=0.02 respectively). When assessing the impact of increasing severity of each morbidity, again worsening clinical hypoxia (aOR 1.42 increase with each increase in grade, p=0.01) and portal variceal disease (aOR 1.80 with each increase in grade, p=0.01) had differential effects on mortality. Risk of death increased with greater number of FCF morbidities. Having 2 or more of the 7 univariately significant morbidities was the value best discriminating survivors from those who died (Area under the curve 0.67; sensitivity 78%, negative predictive value 93%). Conclusion: Clinical hypoxia and portal variceal disease confer independent risk for non-survival in patients with Fontan from WL to 1 year after HT. Additionally, the magnitude of mortality risk for both hypoxia and varices worsens as disease severity worsens. Given the impact, consistent evaluation for these morbidities and timely referral for heart failure evaluation is warranted.