Abstract 2470: Visually Guided Ablation of Perimitral Flutter: A Novel Approach to Avoid Epicardial Energy Delivery During Blockade of the Superior Mitral Isthmus
Background: Perimitral flutter is a common arrhythmia after atrial fibrillation ablation procedures. A linear ablation at the mitral isthmus (MI) between the inferior left pulmonary vein (LPV) ostium and the mitral annulus (MA) is commonly performed (inferior MI). To achieve bidirectional conduction block across the line epicardial ablation is required in up to 70% of the cases, thereby increasing the risk for serious complications.
Methods and Results: Twelve patients (9 male, 57±9 yrs) presented with persistent perimitral flutter (mean CL 261±23 ms) 95±16 days after an index pulmonary vein isolation procedure. In none of the patients ablation of complex fractionated atrial electrograms or left atrial (LA) linear lesions had been performed. LA diameter was 45±5 mm. After LA electroanatomical reconstruction, visualization of the LA appendage (LAA) was performed by biplane angiography (RAO 30°/15° cranial; LAO 60°/0°). Entrainment manoeuvres proved the posterior-inferior LAA neck being critical part of the re-entrant circuit. An ablation line was drawn from the superior LPV ostium to the MA across the posterior-inferior LAA neck using a 3.5 mm irrigated tip catheter (40W, 25ml/min flow, 43°C maximal temperature). Bidirectional block across the MI was achieved in all patients without epicardial ablation. Total ablation time was 689±411 secs for an ablation line of 27±7 mm. Importantly, no delayed LAA activation was observed. Total procedure and fluoroscopy times were 145±47 min and 14±7 min, respectively. No complications occurred.
Conclusion: Visually guided blockade of the superior mitral isthmus appears to be a promising novel approach to avoid epicardial energy delivery during perimitral flutter ablation.