The significance of persistent atrial late potentials in right atrium during biatrial pacing

Background: Atrial conduction disturbances are a known substrate of re-entrant atrial arrhythmia, and their detection is important for the selection of proper therapy. Time-domain analysis of P-wave in signal-averaged ECG (SA-ECG) recorded from chest leads is an accepted method evaluating inhomogeneity of atrial excitation, predictive for atrial arrhythmias. Biatrial (BiA) pacing created a new therapeutic option for patients with atrial arrhythmias. The aim of our study was to estimate the effect of BiA pacing on SA-ECG recorded from conventional external and from intraatrial leads. Methods: Recordings were performed on 24 patients during BiA pacing system implantation. A surface SA-ECG was obtained from orthogonal leads, and intraatrial signals were recorded and averaged separately from the right and left atria at sinus rhythm and BiA pacing. We analyzed standard SA-ECG parameters (P/A wave duration, RMS20 and LAS5) and the presence of atrial late potentials (ALP-Pdur > 125 ms and RMS20 < 2.40 mV). Results and conclusions: BiA pacing favorably modifies SA-ECG parameters in the right and left atrium. BiA pacing significantly shortens P duration, significantly increases RMS20 and reduces atrial late potentials (ALP) occurrence in most patients in comparison to sinus rhythm both atria. ALP are still present in 46% of patients in spite of effective BiA pacing, which can be observed mainly in the right atrium and is connected with increased risk of atrial fibrillation recurrence. This phenomenon suggests a limited effect of RAA-based BiA pacing on the synchrony of atrial activation, and a search is needed for another right atrial lead location for permanent BiA pacing. (Cardiol J 2008; 15: 26–38)