4.2 The anatomical differences between MPL and CPL
The distance from the posterior line to the anterior aspect of the esophagus was mainly contributed by the myocardium of the LAPW, parietal pericardium, and the fibrofatty tissue.13 However, the parietal pericardium was identified via histological examination, whereas it was almost impossible to identify this parameter from the CT images in the narrow space between LAPW and the esophagus. In the CT image analyses, the myocardium and the fat pad were the main evaluating factors for the distances. Previous studies indicated that the CPL overlap with the LAPW might be responsible for the esophageal injury and even the atrial-esophageal fistula (AEF).8, 17 Moreover, the location of the AEF was commonly related to the ablation lines of the left inferior PV-LA junctions.17, 18 In our study, instead of CPL, we employed MPL, defined by starting at the anterior-inferior part of left PV, which was at a longer distance from the esophagus (Figure 1). Therefore, the esophagus was separated from LAPW by the left inferior PV, which protected it from ablation injury.