Thromboembolic Risk After Atriopulmonary, Lateral Tunnel, and Extracardiac Conduit Fontan Surgery

BACKGROUND Thromboembolic events contribute greatly to morbidity and mortality following Fontan surgery for univentricular hearts. OBJECTIVES This study sought to evaluate the effect of type of Fontan surgery on thromboembolic risk. METHODS A North American multicenter retrospective cohort study enrolled 522 patients with Fontan palliation consisting of an atriopulmonary connection (APC) (21.4%), lateral tunnel (LT) (41.8%), or extracardiac conduit (EC) (36.8%). Thromboembolic complications and new-onset atrial arrhythmia were reviewed and classified by a blinded adjudicating committee. Thromboembolic risk across surgical techniques was assessed by multivariable competing-risk survival regression. RESULTS Over a median follow-up of 11.6 years, 10- and 20-year freedom from Fontan conversion, transplantation, or death was 94.7% and 78.9%, respectively. New-onset atrial arrhythmias occurred in 4.4, 1.2, and 1.0 cases per 100 person-years with APC, LT, and EC, respectively. APC was associated with a 2.82-fold higher risk of developing atrial arrhythmias (p < 0.001), with no difference between LT and EC (p = 0.95). A total of 71 thromboembolic events, 32 systemic and 39 venous, occurred in 12.8% of subjects, for an overall incidence of 1.1%/year. In multivariable analyses, EC was independently associated with a lower risk of systemic (hazard ratio HR: 0.20 vs. LT; 95% confidence interval CI: 0.04 to 0.97) and combined (HR: 0.34 vs. LT; 95% CI: 0.13 to 0.91) thromboembolic events. A lower incidence of combined thromboembolic events was also observed with antiplatelet agents (HR: 0.54; 95% CI: 0.32 to 0.92) but not anticoagulation (p = 0.53). CONCLUSIONS The EC Fontan was independently associated with a lower thromboembolic risk after controlling for time-varying effects of atrial arrhythmias and thromboprophylaxis.