Correlation of Signal‐Averaged P Wave with Electrophysiological Testing for Atrial Vulnerability in Strokes of Unexplained Etiology

Abstract

Atrial fibrillation is considered the main cause of cardioembolic strokes. After detailed investigations, about 30% of ischemic strokes remain unexplained. A percentage of these ischemic attacks may result from asymptomatic episodes of paroxysmal atrial fibrillation (PAF). Previous studies have demonstrated that electrophysiological testing and signal-averaged P wave (SAPW) ECG are useful to detect patients with PAF. Twenty patients with unexplained ischemic strokes had electrophysiological studies (EPS) to determine atrial vulnerability and SAPW recordings. At EPS, patients were classified in group I (10 patients) if they had a latent atrial vulnerability index < 2 and/or more than 1 minute of sustained atrial arrhythmia. Otherwise they were classified in group II (10 patients). In group I, the filtered P wave duration was greater: 142 versus 120 msec (P = 0.03) and RMS 30 tended to be lower: 2.54 versus 4.13 microV (P = 0.11) than in group II. A filtered P wave duration > 125 msec associated with a RMS 30 < 3 microV had a positive predictive value of 78% and a negative predictive value of 88% for the detection of patients with abnormal atrial vulnerability at EPS. SAPW may be useful to identify patients at risk of PAF who may be candidates for EPS.