P wave signal-averaged electrocardiogram as a new marker for atrial tachyarrhythmias in postoperative Fontan patients

OBJECTIVES This study was undertaken to determine the potential role of P w ave signal-averaged electrocardiogram (PSAECG) for risk assessment of atria l tachyarrhythmias (ATs) in patients after Fontan operation. BACKGROUND Onset of atrial flutter/fibrillation (AFF) in patients who have undergone Fontan operation for univentricular hearts constitutes an unfavor able clinical event associated with a high risk of cardiovascular complicat ions. There is no data available on PSAECG in postoperative Fontan patients to predict potential susceptibility to ATs. METHODS Twenty-four post-Fontan patients and 15 age-matched healthy subject s were prospectively studied with PSAECG, and the following measurements we re made: filtered P wave duration (FPWD), P wave vector integrals (PINTs), root-mean-square voltage for the initial 30 ms (RMSi30), and duration of pe rsistent amplitude signals <4 mu V from the beginning of the P wave(Di4). RESULTS The FPWDs were significantly longer in the study group patients wit h ATs when compared with the study group patients without ATs (p < 0.01) an d compared with the controls (p < 0.001). An FPWD cut point of 135 ms resul ted in a sensitivity of 71% and a specificity of 81% in differentiating pat ients with ATs from patients without ATs among the postoperative Fontan pat ients. The PINT was significantly greater in Fontan patients with AFF and a lso without AFF when compared with controls (p < 0.01, p < 0.05, respective ly). The RMSi30 and the Di4 were not significantly different between study and control groups. CONCLUSIONS Signal averaged P wave duration is significantly prolonged in p ostoperative Fontan patients. A prolonged signal-averaged P wave duration m ay be an effective noninvasive marker to predict risk of development of ATs in this patient group. (C) 2000 by the American College of Cardiorogy.