High prevalence of cooled tip use as compared with 8-mm tip in a multicenter Italian registry on atrial fibrillation ablation: Focus on procedural safety

Background Whether cooling catheters should be preferred for atrial fibrillation (AF) ablation is not yet clear. Methods From April 2005 to October 2006, 991 (74% men) consecutive patients who underwent AF ablation were prospectively enrolled in 10 Italian centers. For the present subanalysis, patients were ranked in the two study groups on the basis of the catheter system chosen: 8-mm tip was used in 86 patients (9% conventional group) and open- irrigated tip in 905 patients (91% cooled group). Results The registry clinical data of both groups showed marked heterogeneity due to the fact that the higher number of patients of the cooled group had longer AF history (4.9 ± 4.1 versus 1.2 ± 1.8 years; P = 0.0001), permanent/persistent AF (41.2 versus 27.9%; P = 0.01), and larger left atrium (LA) size (44.1 ± 6.2 versus 33.4 ± 10.5 mm; P- 0.00001). Moreover, they underwent a longer procedure (207.2 ± 70.8 versus 85.2 ± 58min; P = 0.00001), with longer fluoroscopy time (36.5 ± 20.1 versus 15.6 ± 12 min; P- 0.0000), and LA roof ablation lines were more frequently added (29.6 versus 3.5%; P< 0.0001). Data were confirmed in the multivariate analysis, in which a longer procedure [odds ratio (OR) 1.018; 95% CI 1.009-1.027; P = 0.0001], added linear lesions (OR 16.847; 95% CI 4.288-66.190; P = 0.0001), and a longer AF history (OR 1.311; 95% CI 1.063-1.616; P = 0.01) continued to characterize the cooled group. Even though the lack of homogeneity of the groups could not render any reliable comparison about safety, we report that the rate of cumulative complications (4.7 versus 3.8%; P = NS), cerebral thromboembolism (0 versus 0.4%; P = NS), pulmonary vein (PV) stenosis (0 versus 0.5%; P = NS), pericardial effusions or tamponade (1.2 versus 1.5%; P= NS), and groin complications (4.7 versus 2.0%, P= NS) was low and similar in both the groups. Conclusion In the present subanalysis, both the systems showed a similar safety procedural profile, though the lack of homogeneity observed in the two study groups could render any straight conclusion as mere speculation. The longer availability and the consequent higher use of open- irrigated catheters technology for LA ablation in Europe could explain the large preference given to the latter system in the present registry.