No Sbustrate Peri-mitral Atrial Flutter: Electrophysiological Characteristic And Therapeutic Strategy

Objective:Peri-mitral atrial flutter(PMFL)can be terminated by empirical mitral isthmus(MI)ablation,but the procedure is proarrhythmic.Furthermore,the underlying mechanisms of PMFL have not been described.The purpose of this study was to determine the clinical feature and electrophysiological characteristic of no substrate PMFL(N-PMFL)in patients during atrial fibrillation(AF)ablation.Methods:The study consisted of 39 patients who developed PMFL following AF ablation.Electroanatomical mapping were performed using 3-dimensioned electroanatomical mapping system(CARTO,Biosense Webster system or EnSite-NavX system).Quantitative estimation of the bipolar voltage,conduction time and conduction velocity(CV)was measured using 3-dimensional mapping in three areas around the mitral annulus(MA).These regions were defined as the septal-anterior wall(SAW)area from coronary sinus ostium(CSo)to the inferior orifice of left atrial appendage(LAA),The posterior inferior wall(PIW)area cover the CSo to the 4 o'clock of MA,and the MI area covers the area from the LAA inferior orifice to the 4 o'clock position,respectively.Results:Of the 39 PMFL patients 12 Included in this study.10 patients with paroxysmal AF and 2 patients with persistent AF.Mean patients age was 57.6±10.2years,and 92%of patients were male.Median History of AF were 36 months.Average LA diameter was 41.1±4.2mm and average left ventricular ejection fraction was 63.8%±3.9%.Mean tachycardia cycle length of PMFL was 197.8±15:4ms.No low-voltage or abnormal electrograms was found in all patients around MA.There was no difference of the mean voltage in the three area(MI:1.55 ±0.53mV,SAW:1.58±0.45mV,PIW:1.44±0.48mV,P= 0.63).CV in the 3 area had similar findings(MI:0.75 ±0.14m/s,SAW:0.74 ±0.14m/s,PIW:0.83 ± 0.19m/s,P = 0.34).Cardioversion without further ablation after circumferential pulmonary vein isolation(CPVI)was done in all patients.After a mean follow-up of 18 months,one paroxysmal AF patient received redo procedures for recurrence AF due to "gap".Conclusions:No-substrate PMFL more commonly seen in structure normal and paroxysmal AF patients with short tachycardia cycle length probably caused by electrical remodeling.It is reasonable for N-PMFL might not further ablation after cardioversion.