First Report on Atrial Leadless Pacing in an Extra-Cardiac Fontan Patient.

No reports on atrial leadless pacing have been demonstrated in patients with the extra-cardiac Fontan palliation. We present a case of a patient with an extra-cardiac Fontan and an alternative to pacing for symptomatic bradycardia in the setting of sinus node dysfunction. After internal review board approval, a retrospective case review was performed with follow-up of atrial leadless pacing in a patient with an extra-cardiac Fontan. A 19-year-old male with a medical history of dextro-transposition of the great arteries and valvar and sub-valvar pulmonary stenosis, hypoplastic pulmonary arteries, and an aberrant right coronary artery with eventual Glenn and Fontan palliation had intermittent sinus pauses with a failing epicardial pacemaker system. Given extremely low impedance values and eventual unipolar phrenic pacing after failed bipolar capture, he underwent an atrial pacing study and leadless pacemaker implant. Implant values demonstrated an atrial threshold of 5.5 V at 0.4 ms, impedance at 550 ohms, and sensing at < 1 mV. He was programmed AAIR (VVIR) 60 bpm and discharged on Xarelto 20 mg once a day. Follow-up at 3 months demonstrated no intracardiac thrombus, 8% atrial pacing, threshold of 2.0 V@0.4 ms, impedance of 470 ohms, and R-wave of 1 mV. The estimated device longevity was 17.9 years at last follow-up. Atrial leadless pacing is feasible in the extracardiac Fontan patient from outside of the atrium with higher but acceptable capture threshold, without complication. Larger patient population data sets are needed to assess the safety of this type of pacing long-term.