Integrated Clinical and Magnetic Resonance Imaging Assessments Late After Fontan Operation

BackgroundSeveral clinical and cardiac magnetic resonance (CMR)-derived parameters have been shown to be associated with death or heart transplant late after the Fontan operation.ObjectivesThe objective of this study was to identify the relative importance and interactions of clinical and CMR-based parameters for risk stratification after the Fontan operation.MethodsFontan patients were retrospectively reviewed. Clinical and CMR parameters were analyzed using univariable Cox regression. The primary endpoint was time to death or (listing for) heart transplant. To identify the patients at highest risk for the endpoint, classification and regression tree survival analysis was performed, including all significant variables from Cox regression.ResultsThe cohort consisted of 416 patients (62% male) with a median age of 16 years (25th, 75th percentiles: 11, 23 years). Over a median follow-up of 5.4 years (25th, 75th percentiles: 2.4, 10.0 years) after CMR, 57 patients (14%) reached the endpoint (46 deaths, 7 heart transplants, 4 heart transplant listings). Lower total indexed end-diastolic volume (EDV_i) was the strongest predictor of transplant-free survival. Among patients with dilated ventricles (EDV_i ≥156 ml/BSA^1.3), worse global circumferential strain (GCS) was the next most important predictor (73% vs. 44%). In patients with smaller ventricles (EDV_i <156 ml/BSA^1.3), New York Heart Association functional class ≥II was the next most important predictor (30% vs. 4%).ConclusionsIn this cohort of patients late after Fontan operation, increased ventricular dilation was the strongest independent predictor of death or transplant (listing). Patients with both ventricular dilation and worse GCS were at highest risk. These data highlight the value of integrating CMR and clinical parameters for risk stratification in this population.