AVNRT Ablation Success and Risks — EECC MCQ

Correct answer: E — Catheter ablation of the slow pathway for AVNRT has a success rate >95% with a recurrence rate <5%; the main risk is inadvertent AV block requiring permanent pacemaker (~0.5-1% in experienced hands)

AVNRT is the most common regular SVT. The re-entrant circuit uses the fast and slow AV nodal pathways. Catheter ablation targets the slow pathway (located in the posteroseptal region near the coronary sinus ostium) using RF energy or cryoablation. The ESC 2019 SVT Guidelines report: (1) success rate >95%; (2) recurrence rate <5%; (3) major complication: inadvertent complete AV block requiring permanent pacemaker (~0.5-1% — risk is lower with cryoablation, which produces reversible lesions that can be halted if AV conduction is compromised during the freeze). Other risks: vascular access complications, pericardial effusion/tamponade (<0.5%), radiation exposure. Ablation is recommended (Class I) for recurrent symptomatic AVNRT or for patients who prefer definitive cure over long-term medication. First-line medication alternatives are beta-blockers or verapamil/diltiazem.

Reference: ESC (2019): SVT Guidelines