Abstract
BACKGROUND: Cryoablation is an alternative to radiofrequency ablation for the treatment of cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL). However, the anatomical features that make achieving a CTI conduction block using cryoablation challenging remain unclear. METHODS: This study included 100 consecutive patients who underwent CTI cryoablation for AFL. Patients were divided into two groups: the first-pass group, in which first-pass CTI conduction block was achieved (n = 72) and the non-first-pass group, in which it was not achieved (n = 28). We analyzed the anatomical features and the temperature changes of the catheter during the first sequential CTI cryoablation. RESULTS: The distance from the CTI to the right coronary artery (RCA) in the first-pass group was significantly longer than that in the non-first-pass group (p < 0.001). The time to reach nadir freezing temperature in the ventricular side of the CTI was significantly shorter in the first-pass group than in the non-first-pass group (p < 0.001). The time to reach nadir freezing temperature at the ventricular side of the CTI correlated inversely with the distance from the CTI to the RCA (R = -0.410, p < 0.001). The distance from the CTI to the RCA was the only significant factor associated with achieving first-pass CTI conduction block (odds ratio, 4.801, p < 0.001). CONCLUSIONS: The distance from the CTI to the RCA was significantly associated with achieving first-pass CTI conduction block by cryoablation. The warming effect of the RCA blood flow might prevent the CTI conduction block during cryoablation.