Conduction Time Around the Mitral Valve Annulus Could Predict the Incidence of Peri-Mitral Atrial Tachycardia

Background Empirical ablation for mitral isthmus (MI) for AF patient is sometimes challenging for its complex anatomy and wall thickness. It would be helpful in determining the ablation strategies if it could be predicted in advance that peri-mitral atrial tachycardia (PMAT) would occur. Using 3D mapping, a method to confirm MI block has been reported using E-PMCT (estimated peri-mitral conduction time: the doubling the time between coronary sinus (CS) pacing and the wave-front collision at the opposite side of the mitral annulus). Purpose We investigated whether E-PMCT correlated with cycle length of PMAT and was involved in the establishment of PMAT. Methods We retrospectively investigated the AF patients who were created the LA map during CS pacing with multipolar mapping catheter which could measure E-PMCT after pulmonary vein isolation. Amon these cases, 1) PMAT was observed spontaneously or induced (PMAT group, N=25, 68.6±10.9 years old, male 15) and none of the AT occurred by the provocation test and during follow up (no-AT group, N=53, 65.2 years old , male 38) were analyzed. In these group, we evaluated the relationships between E-PMCT and tachycardia circuit of PMAT. Results E-PMCT was significantly longer in PMAT group than non-AT group(216.5±30ms vs 166.7ms, p<0.005). Strong positive correlation was observed between cycle length of PMAT and E-PMCT (Person’s r=0.85, p<0.001). PMAT was non induced in patients with E-PMCT less than 176ms. According to the ROC curve, AUC for the detection of the non-AT group was 0.908 (95% CI 0.843-0.974, sensitivity 91.7%, specificity 81.1%) with the cut off value E-PMCT less than 180ms. The slow conduction during CS pacing were consistent with slow conduction during PMAT in this study. Although left atrial diameter, ejection faction, type of AF(paroxysmal or not), low voltage area in the left atrium and mitral annulus size in 3D mapping system was also different between PMAT group and non-AT group in the univariate analysis, E-PMAT was strongest predicter of occurrence of PMAT in multivariate analysis. Conclusion E-PMCT obtained after PVI could predict the non-inducibility of PMAT and was helpful to decision making for ablation strategy.