Outcome of direct current cardioversion for atrial arrhythmia in adult Fontan patients

Background Limited data are available about direct current cardioversion (DCCV) in Fontan patients. Methods Retrospective review of adult Fontan patients that underwent DCCV for atrial arrhythmias at Mayo Clinic, 1994-2014. Study endpoints were to determine procedural success, safety, and the freedom from arrhythmia recurrence after DCCV. Procedural success was defined as termination of the presenting atrial arrhythmia prior to leaving the cardioversion suite. Results 86 patients underwent 152 DCCV; age 27 ± 8 years; male 49 (57%); atriopulmonary Fontan, 64 (74%); atrial flutter/interatrial reentry tachycardia 125 (82%). Freedom from recurrence was 84% and 47% at 12 and 36 months; freedom from repeat DCCV was 91% and 64% at 12 and 36 months. Procedural failure occurred in 41 (27%); predictors of procedural failure were older age (HR 1.91, CI 1.16-2.73 per decade) and prior DCCV (HR 2.71, CI 1.22-3.21). Concomitant oral class I or III antiarrhythmic medication was associated with an increased likelihood of success (HR 0.64, CI 0.41-0.87). Predictors of recurrence were older age (HR 3.26, CI 1.19-6.55 per decade); duration of arrhythmia (HR 1.87, CI 1.14-2.56 per decade); and presence of atriopulmonary Fontan (HR 1.54, CI 1.27-1.85). Procedural complications were symptomatic bradycardia in 2 cases (1%). No thromboembolic complications or deaths occurred. Conclusion DCCV in Fontan patients is safe but is associated with significant procedural failure and recurrence rates. Ideally, antiarrhythmic medication should be instituted prior to DCCV in stable patients and DCCV alone should be considered as a temporizing measure to maintain sinus rhythm.