Left atrial thickness under the catheter ablation lines in patients with paroxysmal atrial fibrillation: insights from 64-slice multidetector computed tomography

A detailed understanding of the left atrial (LA) anatomy in patients with atrial fibrillation (AF) would improve the safety and efficacy of the radiofrequency catheter ablation. The objective of this study was to examine the myocardial thickness under the lines of the circumferential pulmonary vein isolation (CPVI) using 64-slice multidetector computed tomography (MDCT). Fifty-four consecutive symptomatic drug-refractory paroxysmal AF patients (45 men, age 61 ± 12 years) who underwent a primary CPVI guided by a three-dimensional electroanatomic mapping system (Carto XP; Biosense-Webster, Diamond Bar, CA, USA) with CT integration (Cartomerge; Biosense-Webster) were enrolled. Using MDCT, we examined the myocardial thickness of the LA and pulmonary vein (PV) regions in all patients. An analysis of the measurements by the MDCT revealed that the LA wall was thickest in the left lateral ridge (LLR; 4.42 ± 1.28 mm) and thinnest in the left inferior pulmonary vein wall (1.68 ± 0.27 mm). On the other hand, the thickness of the posterior wall in the cases with contact between the esophagus and left PV antrum was 1.79 ± 0.22 mm (n = 30). After the primary CPVI, the freedom from AF without any drugs during a 1-year follow-up period was 78 % (n = 42). According to the multivariate analysis, the thickness of the LLR was an independent positive predictor of an AF recurrence (P = 0.041). The structure of the left atrium and PVs exhibited a variety of myocardial thicknesses in the different regions. Of those, only the measurement of the LLR thickness was associated with an AF recurrence.