Anatomic Characteristics of the Left Atrial Isthmus in Patients with Atrial Fibrillation: Lessons from Computed Tomographic Images

• Published in: Journal of cardiovascular electrophysiology Vol. 17; no. 12; pp. 1274 - 1278
• Main Authors: CHIANG, SHUO-JU, TSAO, HSUAN-MING, WU, MEI-HAN, TAI, CHING-TAI, CHANG, SHIH-LIN, WONGCHAROEN, WANWARANG, LIN, YENN-JIANG, LO, LI-WEI, CHEN, YI-JEN, SHEU, MING-HUEI, CHANG, CHENG-YEN, CHEN, SHIH-ANN
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.12.2006
• Subjects: Anthropometry - methods; atrial fibrillation; Atrial Fibrillation - diagnostic imaging; Atrial Fibrillation - epidemiology; Atrial Fibrillation - pathology; computed tomography; Female; Heart Atria - diagnostic imaging; Heart Atria - pathology; Humans; isthmus; Male; Middle Aged; Reproducibility of Results; Sensitivity and Specificity; Taiwan - epidemiology; Tomography, X-Ray Computed - statistics & numerical data
• ISSN: 1045-3873; 1540-8167
• DOI: 10.1111/j.1540-8167.2006.00645.x

Introduction: Left atrial (LA) isthmus ablation was reported to improve the success rate of catheter ablation of paroxysmal atrial fibrillation (AF). LA isthmus ablation could also cure a subset of LA flutter. Therefore, understanding the anatomy of the LA isthmus is important for performing the ablation effectively. Methods and Results: Group I included 45 patients (40 male, mean age = 50 ± 13 years) with paroxysmal AF who underwent catheter ablation. Group II included 45 patients (37 male, mean age = 54 ± 10 years) without a history of AF. They underwent a 16‐slice multidetector computed tomography (MDCT) scan to delineate the LA structures before the ablation procedure. The average length of the LA isthmus was longer in group I than in group II (lateral isthmus: 3.30 ± 0.68 vs 2.71 ± 0.60 cm, P < 0.001; medial isthmus: 5.12 ± 0.94 vs 4.45 ± 0.63 cm, P < 0.001), and morphological patterns of lateral and medial isthmus were similar between groups. In addition, the average depth of lateral isthmus was similar between groups (0.62 ± 0.32 vs 0.55 ± 0.33 cm, P = 0.41), but the average depth of medial isthmus was larger in group I than in group II (0.60 ± 0.32 vs 0.44 ± 0.25 cm, P = 0.01). The medial isthmus had more ridges, as compared to the lateral isthmus (13% vs 0%, P = 0.026). Furthermore, the distances between esophagus and lateral isthmus were longer in group I than in group II (at the middle of isthmus and mitral annulus level: 21.0 ± 4.8 vs 18.4 ± 6.0 mm, P < 0.001; and 37.1 ± 5.7 vs 29.6 ± 8.1 mm, P < 0.001, respectively). Conclusion: The LA isthmus was longer in the AF patients. The morphology of the isthmus was variable. Compared with the lateral isthmus, the medial isthmus was longer and had more ridges. A peculiar configuration of the isthmus provided by CT images could influence the ablation strategy.