Multi-Center Comparison of Long-Term Outcomes: Extra Cardiac Conduit Fontan vs. Lateral Tunnel Fontan at 15-Year Follow-Up

L. M.. Seese¹, M. Schiff², V. Morell³, L. Olivieri¹, A. Christopher¹, R. Rathod⁴, J. Kreutzer¹, M. Castro-Medina⁵, J. Da Silva⁶, L. Da Fonseca Da Silva¹, M. Viegas³, T. Alsaied^1
1Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania ²University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania ³UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania ⁴Boston Children's Hospital, Boston, Massachusetts ⁵UPMC Chilldren's Hospital of Pittsburgh, Pittsburgh, Pennsylvania ⁶Children's Hospital of Pittsburgh, UPMC, Blawnox, Pennsylvania

Purpose: The extracardiac conduit (ECC) and the lateral tunnel (LT) are the most prevalent systemic venous drainage strategies for the Fontan operation. Understanding the long-term performance of LT and ECC has presented challenges in prior studies. We utilized a multicenter, international database to compare the outcomes of both strategies.

Methods: The FORCE (Fontan Outcomes Registry using CMR Examinations) Fontan registry was queried for patients who underwent ECC or LT Fontan after the year 2000. To mitigate differences between the two groups, 1:1 propensity score matching based on patient sex, age at Fontan surgery, dominant ventricular morphology, suspected heterotaxy, cardiac diagnosis, and calendar year of Fontan surgery was employed. We evaluated each clinical component individually as well as in a composite Fontan outcome variable that included: death, sustained atrial arrhythmias, emergent cardioversion, plastic bronchitis, protein losing enteropathy, catheter-based intervention on the Fontan pathway, and listing for transplantation. Kaplan-Meier survival curves and log-rank tests were used to compare freedom from key clinical outcomes between groups. Shared cluster-level frailty Cox regression models were then used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the relationship between Fontan surgery type and the targeted outcomes, accounting for patients nested within unique sites.

Results: 3072 patients (1,182 ECC and 690 LT) were identified. Propensity score matching resulted in 1290 patients (645 ECC and 645 LT). The median follow-up in Fontan years was 13.0 (IQR: 9.1-16.3). In matched samples, rates of the Fontan composite outcome (32.4% vs 19.8%), sustained atrial arrhythmias (15.0% vs 5.0%), emergent cardioversion, defibrillation, or arrhythmogenic cardiac arrest (2.6% vs 0.8%), and Fontan pathway catheter-based intervention (7.1% vs 3.6%) were significantly higher for LT patients (all, p< 0.05). In the unmatched and matched cohorts, ECC and LT patients had similar rates of mortality, sustained ventricular arrhythmias, pacemakers, plastic bronchitis, PLE, and listing for transplantation (all, p>0.05). Kaplan-Meier analysis demonstrated that the 5-year, 10-year, and 15-year freedom from the composite Fontan outcome was 94.5%, 88.3%, and 79.8% for ECC patients, respectively, compared to 90.2%, 80.9%, and 68.3% for LT patients (Figure, log-rank p< 0.0001). In the matched cohort, the majority of individual variables in the Fontan composite outcome trended towards lower hazards favoring the ECC group. ECC patients had significantly lower hazard for atrial arrhythmia (HR=0.33, 95% CI: 0.20, 0.54, p< 0.0001). Moreover, the ECC patients had a 28% lower hazard of experiencing the composite Fontan outcome compared to LT patients (HR=0.72, 95% CI: 0.54-0.96, p=0.0257).

Conclusion: We identified that Fontan patients with an ECC had lower hazards for the adverse Fontan composite outcome as well as atrial arrhythmias compared to patients with LT. These outcomes persisted at longitudinal follow-up and after matching for sex, age at Fontan surgery, dominant ventricular morphology, heterotaxy, cardiac diagnosis, and calendar year of Fontan surgery.

Identify the source of the funding for this research project: None