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 ident ification of the coexistence of sinus node dysfunction (SND) has therapeuti c 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-ave raged electrocardiography was recorded with the P-wave-triggering technique . The root mean square voltage for the initial 30 MS and the duration of in itial low-amplitude signals <4 <mu>V of signal-averaged P wave were measure d in the vector magnitude. The criteria of EP were defined as "the root mea n square voltage for the initial 30 MS <3.0 <mu>V and the duration of initi al low-amplitude signals <4 <mu>V >22 MS." SND was diagnosed by use of the conventional 12-lead electrocardiography, 24-hour Halter monitoring, and be dside 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 t he other 111 patients with Paf without EP (P<.0001). EP gave a sensitivity of 78% and a specificity of 84% for the defection of SND in patients with P af. Conclusion EP would be useful for the identification of SND in patients wit h Paf.