Prognostic Value of Cardiac Magnetic Resonance in Fontan Patients—A Multicenter Study

Background: Patients with a Fontan circulation experience significant long-term morbidity and mortality. Our study aimed to determine CMR-based risk factors for adverse outcomes in a larger cohort of Fontan patients.

Methods: This retrospective multicenter study included 502 Fontan patients (mean age 15.4 ± 9.7 years) from five congenital heart disease centers in Germany, who underwent CMR as part of routine clinical care. Feature tracking analysis was performed to quantify systolic and diastolic strain values of the single ventricle. If available, flow measurements in the ascending aorta (Ao), inferior (IVC) and superior caval veins (SVC) were assessed and systemic-to-pulmonary collateral flow (SPC) was quantified (= Ao − [SVC + IVC]). The combined end-point consisted of death, heart transplantation (HT), or listing for HT.

Results: Over a median follow-up of 6.6 years (range 0.1–15.6), 39 patients reached the primary endpoint (cardiac death n = 30, HT n = 9). Univariate Cox regression analysis identified that increased single-ventricle EDVi (HR 1.01, 95% CI 1.00–1.01, p < 0.001) and ESVi (HR 1.01, 95% CI 1.01–1.02, p < 0.001) as well as reduced EF (HR 0.97, 95% CI 0.95–10.0, p = 0.02), impaired systolic longitudinal strain (HR 1.10, 95% CI 1.01–1.20, p = 0.03), and circumferential early diastolic strain rate (HR 0.16, 95% CI 0.03–0.95, p = 0.04) were significantly associated with adverse outcomes. In a subgroup of 342 subjects with complete flow measurements, higher SPC flow independently predicted death and HT (HR 1.75, 95% CI 1.05–2.93, p = 0.03) regardless of single ventricle size and function.

Conclusion: Fontan patients with dilated single ventricles and impaired systolic function are at an increased risk for adverse events. Elevated SPC flow emerged as an independent risk factor, suggesting the need to explore underlying mechanisms and effective occlusion strategies for these collaterals.