P-wave morphology and electrical activity of the isolated left atrial appendage on 12-lead ECG in patients with recurrent atrial tachyarrhythmias after pulmonary vein isolation

Purpose: Left atrial appendage isolation(LAAI) may occur during catheter ablation of complex atrial tachyarrhythmias(aTa). We compare P-waves before and after LAAI and characterize LAA activity on the 12-lead ECG after LAAI. Methods: Twenty-five patients were analyzed after LAAI. P-wave amplitude, duration, and morphology before and after LAAI were analyzed. Automaticity in the isolated LAA was identified, and magnified 12-lead surface ECGs were analyzed for LAA activity, amplitude, duration, and morphology. The isolated LAA area was measured using a 3D mapping system. Results: P-wave amplitude and duration during sinus rhythm was 0.09 mV and 103.57 ms before LAAI and 0.09 mV and 102.25 ms after LAAI, respectively. Precordial leads, I, II, III, and aVF were positive. Lead aVR was negative. Lead aVL was −/+. There were no significant differences in P-wave morphology before and after LAAI. Twenty-one of 25 (84%) patients had LAA automaticity after LAAI. Twelve of 21 (57%) patients had automaticity associated with visible LAA activity on the surface ECG. The average LAA activity amplitude and duration was 0.02 mV and 67.7 ms, respectively. Precordial leads, I, II, III, and aVF were positive. Lead aVR was negative/isoelectric. Lead aVL was positive/isoelectric. The mean isolated LAA area was 29.1 cm². The mean percentage area of isolated LAA vs total LA area was 22.6%. Conclusion: LAA activity can be visible on 12-lead ECG in 57% of patients after LAAI. They have smaller amplitudes and shorter durations compared to P-waves.