Conclusion
The MPL was far away from the esophagus with thicker myocardium tissue and more fat pad than the CPL; thus, MPL could serve as a favorable alternative in linear ablation for LAPW isolation.
Keywords: Catheter ablation – atrial fibrillation, Enhanced multidetector computed tomography (CT), Left atrial posterior wall (LAPW) isolation, Modified posterior-inferior line (MPL), Conventional posterior line (CPL)
1 INTRODUCTION
Pulmonary vein (PV) isolation has been considered as the cornerstone for catheter ablation in the treatment of atrial fibrillation (AF).1, 2 However, the ablation of persistent AF (PsAF) remains a challenge for clinical practice. Due to the underlying structural, electrical, and autonomic pathologic remodeling of PsAF, the success rate could decrease over time. Although reports have indicated that atrial and pulmonary vein (PV) muscle sleeve microstructural remodeling is present in AF establishing a vulnerable substrate for AF maintenance, there are more non-PV foci atrial substrates for the maintenance of AF.3 Non-PV foci commonly arise from the left atrial posterior wall (LAPW), left atrial appendage, and the superior vena cava, and so on.4 Based on PV isolation, additional LAPW isolation has been reported as an effective strategy for improving the ablation outcomes for PsAF.5, 6 Furthermore, LAPW isolation has also been performed for paroxysmal AF (PAF).5, 7 One of the classic LAPW isolation approaches involves a wide antral PV isolation, followed by roofline and conventional posterior line (CPL). The CPL is usually connected to the most inferior margin of the inferior PVs6, 8 or the posterior-inferior part of two inferior PVs.9, 10 Due to the anterior aspect of the esophagus was directly opposed to the LAPW, the CPL could not avoid touching the esophagus.11 Therefore, it is predictable that the adjunct ablation on LAPW, theoretically, increases the risk of esophageal injury and even result in an atrio-esophageal fistula (AEF). Previous studies investigated the myocardium of LAPW and tissue layers between LAPW and esophagus by multidetector computed tomography (CT), intracardiac echocardiography, specimen and histological analysis.12-14 However, only a few studies have compared the distance from the endocardium of LAPW to the esophagus between different levels of LAPW.12, 13 In this study, a modified approach of LAPW isolation was proposed by replacing CPL with a modified posterior-inferior line (MPL), which was in a lower region of LAPW than CPL. The anatomical difference between CPL and MPL were compared in patients with AF using enhanced multidetector CT analysis.