Juhani Knuuti

Young Investigator Award Competition : Sunday 3 May 2015, 08

Purpose:Theoutcomeof radiofrequency catheter ablation (RFCA)of atrial fibrillation (AF) has improved by computed tomography (CT) or magnetic resonance (MR) for the characterization of left atrium (LA) anatomy before the procedure. However, no comparative data between CT and MR have been described regarding to the impact of different imaging modality. The aim of this study is to compare the procedural characteristics, overall radiation exposure and clinical outcomes between RFCA guided by image integration with CCT versus CMR. Methods: Four hundred consecutive patients with drug-refractory paroxysmal or persistent AF were randomized to CT (Group 1; N: 200; mean age 61.6+10.9 yo; male:155) or MR (Group 2; N: 200; mean age 59.7+10.4 yo; male:166) for evaluation of LA before RFCA. CT was performed with 64-slices scanner and MR was performed with 1.5-T scanner using a non-triggered contrast enhancement magnetic resonance angiography sequence. All patients were subsequently treated by image integration-supported RFCA. Left atrium diameter, left atrium volume, variant of pulmonary veins anatomy, pulmonary veins ostial dimensions, procedural characteristics, overall radiation exposure and rate of AF recurrence were measured and compared between the two groups. Results: The two groups were homogeneous in terms of demographic characteristics, cardiovascular risk factors, prevalence of persistent AF, medical therapy and echocardiographic characteristics. The mean follow-up was similar (557+302 vs. 523+265 days, respectively, p:0.24). Group 1 showed higher LA volume versus group 2 (117+46 vs. 101+40 mL, p,0.001). The procedural characteristics [fluoroscopy time (32.6+16.0 vs. 35.0+16.6 min, p:0.15); procedural duration (180.2+59.0 vs. 182.8+53.5, p:0.65, pulmonary veins identified (4+0.1 vs. 3.9+0.2, p:0.08); pulmonary veins targeted (3.9+0.4 vs. 3.9+0.4, p: 053); pulmonary veins isolated (3.9+0.4 vs. 3.9+0.4, p:0.9)] and the rate of AF recurrence (29% vs. 26%, p:0.5) were similar between the two groups. Group 1 showed a higher overall cumulative radiation exposure (40.4+23.7 vs. 32.8+23.5, p,0.005). and LA volume measured by MR was the most robust independent predictorofAFrecurrence atmultivariate analysis [(HR:1.08 (1.01–1.15),p:0.02] Conclusions: CT and MR appear to provide similar information before RFCA. However, MR integrationsupported RFCA procedure seems to be associated with a lower overall cumulative radiation despite similar outcome in comparison with CT-guided RFCA.