Change in distant atrial activation patterns during circumferential pacemapping of pulmonic vein ostium: Implications for localizing triggers for atrial fibrillation

Introduction: Unique intracardiac activation patterns recorded from multipolar catheters in the coronary sinus ( CS) and posteromedial right atrium ( RA) when pacing from ostium ( os) of each pulmonic vein (PV) can serve as template for determining PV of origin of atrial premature complexes. Development of an accurate template requires knowledge of variations in activation pattern during pacing from different aspects of same PV. Methods: In 25 patients undergoing catheter ablation for AF, a decapolar Lasso mapping catheter was placed at PV os of interest and multipolar catheters were placed in CS and RA - medial to crista terminalis (CT). For each PV, pacing was performed from Lasso catheter poles 1 through 10. For each bipole paced, activation sequence in CS ( proximal to distal & vice-versa) was assessed, activation time ( pacing stimulus to earliest electrogram recorded in catheters in CS/along CT) was measured and difference (CS-CT time) was determined. Significant interpolar variation was defined as the difference between the shortest and longest CS-CT activation time of greater than or equal to 25 msec when pacing from different bipoles of same PV. Results: In 59 PVs [19 right superior (RS), 20 left superior (LS), 8 right inferior ( RI) and 12 left inferior (LI)], 259 bipoles were paced ( median of 4 bipoles/ PV). During circumferential PV pacing activation sequence in CS catheter was distal to proximal in 84.4% left-sided PVs (LSPV and LIPV) and proximal to distal in 92.6% right-sided PVs (RSPV and RIPV) with no change in activation sequence observed during pacing from different bipoles in same PV. Significant interpolar variation was observed with circumferential pacing in 1 of 19 RSPV (5.3%), 2 of 20 LSPV (10%), 1 of 12 LIPV (8.3%) and none of RIPV. Conclusion: Unique intracardiac activation patterns during ostial pacing from individual PV are not influenced by circumferential location of pacing site.