Identification of sinus node dysfunction by use of P-wave signal-averaged electrocardiograms in paroxysmal atrial fibrillation: a prospective study.

BACKGROUND In patients with paroxysmal atrial fibrillation (Paf), the identification of the coexistence of sinus node dysfunction (SND) has therapeutic implications. This study sought to prospectively determine whether SND in patients with Paf would be identified by use of atrial early potential (EP), low-amplitude potentials early in signal-averaged P wave. METHODS The study population consisted of 149 patients with Paf. Signal-averaged electrocardiography was recorded with the P-wave-triggering technique. The root mean square voltage for the initial 30 MS and the duration of initial low-amplitude signals < 4 microV of signal-averaged P wave were measured in the vector magnitude. The criteria of EP were defined as "the root mean square voltage for the initial 30 MS < 3.0 microV and the duration of initial low-amplitude signals < 4 microV >22 MS." SND was diagnosed by use of the conventional 12-lead electrocardiography, 24-hour Holter monitoring, and bedside electrocardiographic monitoring. RESULTS Thirty-eight of 149 patients with Paf had EP. Eighteen (47%) of 38 patients with Paf and EP had SND, whereas SND was found in only 5 (5%) of the other 111 patients with Paf without EP (P <.0001). EP gave a sensitivity of 78% and a specificity of 84% for the detection of SND in patients with Paf. CONCLUSION EP would be useful for the identification of SND in patients with Paf.