Efficacy of Intra-Operative Cryoablation with Pulmonary Valve Replacement In Patients with Repaired Tetralogy of Fallot

Purpose: Inducible ventricular tachycardia (VT) with programmed ventricular protocol (PVP) has a positive predictive value of 55% for clinical VT in pts with repaired tetralogy of Fallot (TOF). The inducibility of VT and effect of intra-operative cryoablation (IOCA) with pulmonary valve replacement (PVR) is studied in symptomatic pts with repaired TOF.

Methods: Demographics, electrophysiologic, hemodynamic and follow-up data were collected for symptomatic pts with repaired TOF who underwent PVP between January 2002 and June 2011. 

Results: A total of 31 pts underwent PVP for sensed tachycardia, syncope, or documented VT. VT was not inducible in 14 pts (45%) and inducible in 17 pts (55%), of which 10 pts underwent IOCA with PVR. In comparison, the pts with inducible VT were older at presentation (32 yrs vs. 24 yrs, P<0.05) and had wider baseline QRS complexes (164 ms vs. 142 ms, P<0.05). Among 17 pts with inducible VT, PVP induced monomorphic VT (MVT) in 12 pts and polymorphic VT (PVT) in 5 pts. Ablation was performed for 4 pts with MVT and ICD implanted in 3 pts with PVT. IOCA with PVR was performed in 10 pts (8 with MVT and 2 with PVT). The 2 pts with PVT had re-inducible PVT in the follow-up study and underwent ICD implantation. Of the 8 pts with MVT, followed up for 13 months (1 to 31 months), 1 pt died secondary to post-operative ventricular fibrillation, 4 pts underwent follow up PVP for symptoms of sensed tachycardia in 3 pts (38%), and syncope in 1 pt (13%) with no documented tachyarrhythmia. In the follow up PVP, 3 pts had no inducible VT and 1 pt required ablation of fascicular tachycardia. The other 3 pts have remained asymptomatic. All pts in the non-inducible VT group remained asymptomatic on follow up. 

Conclusion: Patients with inducible VT were older at presentation and had wider QRS complexes in comparison to the patients with non-inducible VT. Patients with inducible PVT did not benefit from IOCA requiring ICD implantation. Intra-operative cryoablation appeared relatively effective in patients with an inducible MVT.