Time-Domain Analysis of the ECG P-Wave after External Cardioversion for Persistent Atrial Fibrillation

Abstract

Atrial fibrillation is the most common arrhythmia with an increasing prevalence related to ageing. Its societal impact is large because of the morbidity, predominantly related to stroke as a consequence of embolization from the thrombi in the atrium, but also to heart failure. Normal cardiac impulse initiation begins in the sinoatrial node and then travels through working atrial myocardium. During this time, surface ECG recordings show the P-wave. If the atrial depolarization pattern deviates from the physiological pattern, the morphology of the P-wave changes, resulting in prolonged and highly variable P-waves. Since abnormal P-waves have been observed in patients prone to AF, a more advanced analysis of P-wave characteristics based on the extraction of morphological features might contribute to a better identification of patients at risk. The aim of this study is to evaluate the morphological and time-domain characteristics of the P-wave within 6 months after successful electrical cardioversion. The study included 35 patients with preserved left ventricular function, who underwent successful electrical cardioversion for persistent AF. Five minute ECG recordings were performed for each subject, soon after normal sinus rhythm restoration by external electrical cardioversion, and after 6 months. ECG signals were acquired by using a 16-lead mapping system for high-resolution biopotential measurements (sample frequency 2 kHz, 31 nV resolution, 0-400 Hz bandwidth). Time-domain and morphological characteristics were estimated from averaged P-waves for each lead. The results obtained so far indicate that the morphological and time-domain characteristics of the P-wave do not vary within the 6-months after external successful cardioversion, but can predict AF recurrence.