Electrophysiological study prior to planned pulmonary valve replacement in patients with repaired tetralogy of Fallot.

Electrophysiological study prior to planned pulmonary valve replacement in patients with repaired tetralogy of Fallot.

Bouyer B, Jalal Z, Daniel Ramirez F, Derval N, Iriart X, Duchateau J, Roubertie F, Tafer N, Tixier R, Pambrun T, Cheniti G, Ascione C, Yokoyama M, Kowalewski C, Buliard S, Chauvel R, Arnaud M, Hocini M, Haïssaguerre M, Jaïs P, Cochet H, Thambo JB, Sacher F.

J Cardiovasc Electrophysiol. 2023 Jun;34(6):1395-1404. doi: 10.1111/jce.15940. Epub 2023 May 26.

PMID: 37232426

Take Home Points:

  • Estimating risk of sudden cardiac death (SCD) due to ventricular arrhythmias (VAs) in patients with repaired Tetralogy of Fallot (rTOF) remains difficult.
  • Electrophysiology study (EPS) in patients with rTOF planned for surgical/transcatheter pulmonary valve replacement (PVR) may identify patients at higher risk of VA and provide opportunity for targeted ablation.
  • Nearly 1/3rd of the patients had inducible VA post ablation and inducibility AFTER ablation was associated with VT during follow up, suggesting it as a possible marker for ICD implantation.
  • Among inducible patients, all patients had monomorphic VT except one with polymorphic VT.

Commentary by Dr. Srikant Das (Texas Children’s- Austin) Congenital and Pediatric Cardiac EP section editor: 

The authors examine outcomes in 77 patients following programmed ventricular stimulation with or without ablation in rTOF patients planned for primary valve replacement at a single center.  Their patients underwent PVR either surgically or via transcatheter implantation with a Melody valve.  Their cohort was categorized into low-risk group (72/77) and high-risk group (5/77) based on a risk score model developed by Vehmeijer et al, but they analyzed the patients based on inducibility (VA Inducible =18; VA Non-Inducible 59) at the initial EPS. Among inducible patients, all patients had monomorphic VT except one with polymorphic VT.

During initial EPS, they performed percutaneous endocardial catheter ablation in patients with inducible VT, or with slow conduction within their anatomic isthmuses. Surgical cryoablation was performed when endocardial ablation failed. Failed ablation was defined as failure to achieve block at the target isthmus or VT still inducible after ablation. Among inducible group, AFTER catheter ablation, five (5/15, 33%) patients were still inducible. No complications reported from EPS.

During a follow-up of 74 ± 40 months, they report three patients experienced sustained ventricular arrhythmias. All these patients had inducible VT during their initial EPS. No ventricular arrhythmia was reported during the following period in non-inducible group, and this was statistically significant (p<0.001). Although, VT induced and clinical VT during follow-up did not share morphologically characteristics and cycle lengths. No sudden cardiac death reported in the any cohort. The 5 patients with failed transcatheter ablation and 2 with primary surgical cryoablation underwent repeat EPS three months after the PVR, and none of these patients were inducible. Implantable cardioverter defibrillator (ICD) were implanted in five patients after EPS, four of these for primary prevention, and one for secondary prevention. 

Authors advise/conclude that EPS and possible ablation should be performed prior to all pulmonary valve replacement in patients with rTOF. Ventricular arrhythmia inducibility AFTER initial ablation was associated with VT during follow up, suggesting it as a possible marker for ICD implantation.

Perspective:

Risk for monomorphic VT related to post surgical right ventricular changes are well studied and are the main reason for primary prevention ICD placement. Pulmonary valve replacement and repair in rTOF patients reduces pulmonary regurgitation and decreases right ventricular dilation but it’s longtime impact on ventricular tachycardia and mortality is not well known. Thus, accurate VT risk assessment is paramount.

PVR is the most common re-operation performed in adults with congenital heart disease. The post-surgical VT substrate is still present in patients undergoing PVR. The study provides helpful information regarding feasibility and safety of EPS and ablation prior to PVR. Transcatheter technologies are available to treat certain patients with right ventricular tract dysfunction and use of transcatheter PVR is increasing. There is also concern with certain valves posing an obstacle to future catheter ablation due to longer lengths and sometimes covering areas of target for ablation in the right ventricle.

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