Improved Ventricular Function after TEE-guided Cardioversion of Atrial Arrhythmias in Patients after the Fontan Operation.

OBJECTIVE: Atrial tachyarrhythmias frequently develop after the Fontan operation. Patients with Fontan physiology rely on atrial contribution to cardiac output, and thus control of atrial arrhythmias is important. Outcomes after cardioversion in patients after Fontan have not been reported. We sought to determine if cardioversion results in improved echocardiographic parameters or clinical symptomatology; and, discern risk factors for arrhythmia recurrence.

DESIGN: We retrospectively analyzed the Mayo Clinic echocardiographic database to capture patients after the Fontan operation who underwent transesophageal echocardiography-guided electrical cardioversion from 2000-2015. Clinical and echocardiographic data were collected and compared at baseline and follow-up.

RESULTS: Eight hundred ninety patients with prior Fontan operation underwent echocardiographic evaluation; 341 (38%) developed atrial arrhythmias. Thirty-six patients [20 males, median age 29 (12-51)] underwent transesophageal echocardiography-guided cardioversion of atrial arrhythmias [atrial flutter/intraatrial reentrant tachycardia (75%); atrial fibrillation (25%)]. At follow-up, improvements were noted in ejection fraction by 10% (P < .0001); atrioventricular valve regurgitation grade (39%) (P = .002); New York Heart Association (NYHA) class (61%) (P < .001); and resolution of spontaneous echo contrast in the Fontan circuit (65%) (P < .01). No embolic events occurred following cardioversion. Eighteen patients (50%) developed recurrent atrial arrhythmias at 15 (3-36) months after cardioversion. Five-year freedom from arrhythmia recurrence was 61%. Significant univariate predictors of arrhythmia recurrence were atrial flutter/intraatrial reentrant tachycardia (HR = 4.3, P = .02); NYHA ≥ II (HR = 4.1, P = .03); systemic right ventricle (HR = 5.2; P = .02); and ejection fraction ≤ 40% (HR = 2.8; P = .04). On multivariate analysis, only systemic right ventricle (HR = 3.7; P = .02) remained an independent predictor of arrhythmia recurrence.

CONCLUSION: After the Fontan operation, cardioversion of atrial arrhythmias improves ventricular function, atrioventricular valve regurgitation grade, and NYHA class. Arrhythmia recurrence was common and patients with atrial flutter/intraatrial reentrant tachycardia, systemic right ventricle, or reduced ventricular function may be at risk of arrhythmia recurrence. Further studies are required to identify additional risk factors and protective factors for arrhythmia recurrence.