CTI Ablation for Typical Flutter — EECC MCQ

Correct answer: E — Catheter ablation of the cavotricuspid isthmus (CTI) has a success rate >95% for typical atrial flutter — creating a bidirectional conduction block across the CTI is curative; it is the most effective rhythm control strategy for typical flutter

Typical (CTI-dependent) atrial flutter involves a macro-re-entrant circuit in the right atrium, with the cavotricuspid isthmus (CTI — between the tricuspid annulus and IVC) as the critical slow-conduction zone. CTI ablation creates a line of radiofrequency lesions across this isthmus, interrupting the circuit. Success rate: >95% with a recurrence rate of <5-10%. The endpoint is demonstration of bidirectional CTI conduction block. The 2024 ESC AF Guidelines recommend CTI ablation as first-line for symptomatic typical flutter (Class I, LOE A), as it is curative with minimal risk. Important: ~25-50% of patients with typical flutter will develop AF subsequently (shared risk factors), requiring separate management. Atypical flutter (non-CTI-dependent) involves different circuits (often LA-based) and has lower ablation success rates, requiring detailed electroanatomical mapping.

Reference: ESC (2024): AF Guidelines