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Postablation scar-related atrial tachycardia: turning the spotlight on P-wave analysis and window settings.

Left atrial flutter (AFL) and localized scar-related atrial tachycardia (AT) are the most common tachyarrhythmias that follow catheter or surgical ablation for atrial fibrillation. Three-dimensional activation mapping can be challenging due to large and often multiple areas of scar interspersed with areas of delayed conduction, resulting in complex reentrant circuits.1 In our experience, there are 3 components of mapping that are crucial to localizing the re-entry circuit and guiding catheter ablation: (1) analysis of the P wave on surface ECG, (2) right and left atrial (LA) intracardiac activation sequence from multielectrode catheters positioned at the right atrium (RA; 20 poles) and proximal coronary sinus (CS; 10 poles; Figure 1A), and (3) careful attention to the mapping window settings based on P-wave analysis and the cycle length of the tachycardia.



Figure 1. 
A , Right anterior oblique (RAO) and left anterior oblique (LAO) fluoroscopic projections with duodecapolar catheter with 2-10-2 mm spacing placed in the right atrium (RA) at the tricuspid annular and a decapolar catheter with 2-5-2 mm spacing placed in the proximal coronary sinus (CS). B1 , Counter clockwise tricuspid annular atrial flutter (CCW-TA-AFL) with correlation of RA activation and P wave in leads V1, II, III, and aVF. B2 , Counter clockwise mitral annular atrial flutter (CCW-MA-AFL) with simultaneous atrial activation in the RA and CS and earliest RA activation at 9 to 10 pair electrodes indicating early RA activation at the high RA septum. The shallow upsloping portion in leads II, III, and aVF is much earlier than the P-wave onset in V1. B3 , CW-MA-AFL with early RA activation located at the low or mid septum, propagating to high and low RA with atrial activation in the proximal CS preceding the lateral atrial activation of RA. C , Activation mapping of the RA during CCW-TA-AFL. The atrial …