Proactive Mapping and Preventive Ablation Reduce Defibrillator Implantation Rates in Tetralogy of Fallot

Area of Science:

• Cardiology
• Electrophysiology
• Congenital Heart Disease

Background:

• Patients with repaired tetralogy of Fallot (rTOF) and spontaneous ventricular tachycardia (VT) benefit from ablation of the slow-conducting anatomical isthmus (SCAI).
• Proactive electroanatomical mapping and preventive SCAI ablation in rTOF patients without prior VT may refine selection for primary prevention implantable cardioverter-defibrillators (ICDs).

Purpose of the Study:

• To assess long-term outcomes following proactive electroanatomical mapping and SCAI ablation in rTOF patients without prior VT.
• To compare the impact of this strategy on primary prevention ICD selection versus existing risk stratification methods.

Main Methods:

• Consecutive rTOF patients without prior VT underwent electroanatomical mapping for VT substrate identification (2005-2020).
• SCAI ablation was performed, and ICD implantation was offered via shared decision-making.
• Retrospective ICD eligibility assessment used clinical risk scores, AHA 2018, ESC 2022 guidelines, and mapping/ablation results.

Main Results:

• Of 97 patients, 33% had SCAI and 20% had inducible VT; 87% of attempted SCAI ablations were successful.
• Current guidelines would have qualified 25-51% for ICDs; proactive mapping/ablation identified only 11% as ICD candidates.
• During 58 months follow-up, 4% experienced VT, all post-ablation failure; these patients were identified as ICD candidates.

Conclusions:

• Repaired tetralogy of Fallot patients without SCAI demonstrate excellent long-term outcomes.
• Proactive electroanatomical mapping and preventive SCAI ablation can substantially decrease primary prevention ICD implantation rates compared to current risk prediction methods.