Local coronary flow is associated with an unsuccessful complete block line at the mitral isthmus in patients with atrial fibrillation.

BACKGROUND: The addition of a mitral isthmus (MI) block line after pulmonary vein isolation could lead to a favorable outcome of catheter ablation in patients with atrial fibrillation (AF). However, it is sometimes tough to create a complete MI block line, and the cooling effect because of the local coronary flow may prevent the creation of a successful MI block line. METHODS AND RESULTS: This study enrolled 81 AF patients in whom the creation of an MI block line was attempted in those with persistent or pacing-inducible AF after pulmonary vein isolation. A local coronary artery (LCA) across the MI block line was observed in 43 (53%) of 81 patients, and a bidirectional MI block was successfully accomplished in 53 (65%) of 81 patients, at the estimated MI line. The ratio of a successful MI block line was significantly lower in the patients with an LCA than in those without an LCA (42% versus 92%; P<0.001). The mean diameter of the coronary sinus (0.59 ± 0.18 versus 0.82 ± 0.22 cm; P<0.001) and length of the estimated MI line (33.4 ± 9.9 versus 29.4 ± 7.1 mm; P=0.032) were significantly shorter in the patients with a successful MI block line than in those without a successful MI block line. In the multivariable analysis, an LCA at the MI and a larger coronary sinus diameter were independent risk factors for an unsuccessful MI block line. CONCLUSIONS: Local coronary flow at the MI is associated with an increased incidence of an unsuccessful MI block line.

Multiple arrhythmogenic foci associated with the development of perpetuation of atrial fibrillation.

BACKGROUND: The presence of multiple arrhythmogenic sources may be associated with the perpetuation of atrial fibrillation (AF). In this study, we investigated the hypothesis that multiple foci might be involved in the development of AF persistency. METHODS AND RESULTS: Two hundred fourteen consecutive patients with AF undergoing catheter ablation were enrolled in this study. The location of the arrhythmogenic foci was determined using simultaneous recordings from multipolar catheters before and after pulmonary vein isolation during an isoproterenol administration. We detected 500 arrhythmogenic foci (263 foci as AF initiators, and 237 foci as non-AF initiators). High-dose isoproterenol infusions (ranging from 2 to 20 microg/min) revealed potential arrhythmogenic foci, especially non-pulmonary vein foci (55%). Persistent AF was more highly associated with an incidence of multiple (>2) foci than paroxysmal AF (88% versus 65%, P=0.002), and a multivariate analysis demonstrated that multiple foci (>2) were an independent contributing factor for persistent AF (odds ratio; 95% confidence interval, 4.69; 1.82 to 12.09, P<0.001). In paroxysmal AF, the number of foci was higher in patients with long-term AF (>24 hours) than in those with short-lasting AF (2.64+/-0.14 versus 1.77+/-0.16, P=0.001). In the persistent AF group, the patients with short-lasting AF (<12 months) had a greater number of foci than did those with long-term AF (>12 months) (3.62+/-0.15 versus 1.92+/-0.16, P=0.04). CONCLUSIONS: Multiple foci were likely to be involved in the development of persistent AF. However, if AF persisted for >12 months, they may not have had a significant effect on the AF perpetuation.