Abstract 11209: The Distance From the Right Coronary Artery to the Cavotricuspid Isthmus is a Predictor of First-Pass Conductional Block of Cavotricuspid Isthmus by Cryoablation

Abstract

Background : Several studies have reported that the blood flow in the right coronary artery (RCA), located beneath the anterior cavotricuspid isthmus (CTI), has cooling effect which might prevent CTI block from radiofrequency ablation and make this ablation procedure difficult. However, the details of this effect by RCA blood flow remain unclear in cryoablation of CTI. Methods: This study included 63 consecutive patients (46 men; 66±11 years) who underwent CTI cryoablation for common AFL. A computed tomography (CT) scan with contrast injection was performed before ablation in all patients. Patients were divided into 2 groups: one pass group who achieved first-pass conductional block of the CTI (n=47) and non-one pass group who did not (n=16). CTI ablation was performed with 2.5-min freezing cycles and 8-mm tip cryocatheter. We analyzed anatomical features of the CTI, the presence of Eustachian valves on CT, and the temperature changes at the catheter tip during first pass in CTI cryoablation. Results: The distance from the RCA to the CTI in the one pass group was significantly longer than that in the non-one pass group (2.9±0.7 vs. 2.2±0.6 mm, P <0.001). On the other hand, there was no significant difference in the variants of CTI anatomy or the CTI length or the presence of a Eustachian valve between the two groups. The time to reach the nadir freezing temperature in the anterior CTI, where the RCA was located beneath it, was significantly shorter in the one pass group than in the non-one pass group (31.3±6.5 vs. 34.7±6.1 sec, P =0.034). The time to reach the nadir freezing temperature in the anterior CTI correlated inversely with the distance from the RCA to the CTI (R=-0.404, P =0.001). Using multivariate analysis, the distance from the RCA to the CTI was an independent predictor of achievement of first-pass conductional block of the CTI (odds ratio 8.776, 95% confidence interval 2.358-32.662, P =0.001). The distance from the RCA to the CTI >2.2 mm had 83% sensitivity and 63% specificity to predict one pass conduction block (area under the curve, 0.813). Conclusions: The distance from the RCA to the CTI is a predictor of first-pass conductional block of CTI by cryoablation. The warming effect of the RCA blood flow might prevent CTI block during cryoablation.