Comparison of Voltage Map-Guided Left Atrial Anterior Wall Ablation Versus Left Lateral Mitral Isthmus Ablation in Patients With Persistent Atrial Fibrillation
Is mitral isthmus (MI) block achieved more effectively by voltage-guided left atrial anterior wall (LAAW) radiofrequency ablation (RFA) than by left lateral mitral isthmus (LLMI) ablation?
Voltage mapping was performed during sinus rhythm in 29 patients with persistent atrial fibrillation (AF), and the lowest voltage was found along the LAAW. Based on these results, 200 patients (mean age 59 years) with persistent AF were assigned nonrandomly to either voltage-guided LAAW RFA (n = 100) or LLMI RFA (n = 100). An irrigated-tip ablation catheter and power settings of 30-35 W were used in both groups. If MI block was not achieved after two ablation lines across the LLMI, RFA then was performed in the coronary sinus in the LLMI group. The primary outcome was achievement of bidirectional MI block confirmed by pacing maneuvers.
Bidirectional MI block was achieved significantly more often in the LAAW group (69%) than in the LLMI group. The ablation line was significantly longer in the LAAW group (37.9 mm) than in the LLMI group (26.6 mm). The duration of RFA was 18-19 minutes in both groups. Cardiac tamponade was more frequent in the LLMI group (8%) than in the LAAW group (2%).
Bidirectional MI block is achieved more efficiently and safely by voltage-guided LAAW ablation than by LLMI ablation.
There are at least three reasons that MI block is more difficult to achieve by ablation at the LLMI than the LAAW: 1) a thicker atrial wall, 2) the cooling effects of blood flow through the coronary sinus and circumflex coronary artery, and 3) pouches or other anatomic variants at the LLMI.
Keywords: Heart Atria, Coronary Sinus, Coronary Vessels, Catheter Ablation, Cardiac Tamponade
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