Ablation performed before and after ATP injection
The results of the procedure are summarized in Table 2. Before ATP challenge testing, we performed Box isolation in 4 patients and PV isolation in the remaining three patients. SVC isolation was also performed in 4 patients, and mitral isthmus linear ablation, low voltage area ablation, and CFAE ablation were performed in one patient each.
Spontaneous reconnection and ATP provoked dormant conduction of the isolated veins were documented in 2 patients each. In Case 6, GP ablation within the CS eliminated the ATP-induced AF irrespective of the dormant conduction of the left PV (Figure 1).
The ablation sites following the observation of ATP-induced AF were illustrated in Figure 3. The foci included CS in six patients, RA posterior wall adjacent to the interatrial groove in 2, lateral mitral annulus in 2, ligament of Marshall in 1, RA septum below the foramen ovale in 1, and LA posterior wall below the Box lesion in 1, respectively. Among these trigger foci, we confirmed the vagal response by HFS in CS and RA posterior wall in six and two patients (Figures 1 and 2).
After a median RF time of 2.9 minutes (range 2.5 to 11.3) targeting these foci, all the six patients who received repeat ATP injection became non-inducible except for one patient (Case 1) who did not undergo the GP-based approach.