3.4 Anatomical difference between confined group and unconfined group
Precisely, 38.2% (n = 39) of the AF patients were designated as confined group, and 61.8% (n = 63) as unconfined group (Table 3). There were no differences in the AF types, LA diameter, and the average distance from CPL to the esophagus in the confined group, compared with the unconfined group (p > 0.05). The shortest distance from the spine to LAPW at the left inferior PV level was shorter in a confined group than the unconfined group (P < 0.001). The average distance from the MPL to the esophagus in the unconfined group was longer than the confined group (4.0 ± 1.7mm vs 3.2 ± 1.0mm, P = 0.001, Table 3). The thickness of the myocardium in the course of MPL in the unconfined group was thicker than the confined group (3.1 ± 1.2mm vs 2.6 ± 0.7mm, p = 0.023). When CPL was replaced by MPL, the increased ratio of the distance from the endocardium of the posterior wall to the esophagus was higher in the unconfined group than the confined group (2.4 ± 0.9 times vs 1.9 ± 0.6 times, p < 0.001). The presence and the average thickness of the fat pad were similar in both groups (p > 0.05). The average distance from the MPL to the esophagus was longer than from the CPL to the esophagus in both confined and unconfined groups (3.2 ± 1.0mm vs 1.6 ± 0.4mm, p < 0.001; 4.0 ± 1.7mm vs 1.6 ± 0.3mm, P < 0.001), respectively. Type A esophageal route appeared more frequently in the confined group than the unconfined group (57.1% vs 23.9%, p < 0.05), while Type C esophageal route appeared more frequently in the unconfined group than the confined group (19.4% vs 0%, p < 0.05).