Prediction of Transition to Chronic Atrial Fibrillation in Patients With Paroxysmal Atrial Fibrillation by Signal- Averaged Electrocardiography

Abstract

Background It is well known that paroxysmal atrial fibrillation (PAF) often precedes the establishment of chronic atrial fibrillation (CAF). However, there have been no definite methods to predict the transition from PAF to CAF. The purpose of this report was to determine prospectively whether P-wave–triggered signal-averaged ECG (P-SAE) is useful for the prediction of the transition to CAF in patients with PAF. Methods and Results One hundred twenty-two consecutive patients with PAF were prospectively followed after P-SAE, echocardiography, and 24-hour Holter monitoring at study entry. The duration (Ad) and root-mean-square voltage for the last 30 ms (LP30) of the filtered P wave were measured in P-SAE. The abnormality of P-SAE for the prediction of transition to CAF was defined as Ad ≥145 ms and LP30 <3.0 μV. Twenty-three (19%; group 1) of the patients had the abnormality of P-SAE, whereas the others (group 2) did not. During the follow-up period (mean, 26±12 months), 10 patients (43%) in group 1 acquired CAF, whereas the transition to CAF was observed in only 4 patients (4%) in group 2. Kaplan-Meier analysis revealed that the transition to CAF was significantly observed more often in group 1 than in group 2 (log-rank test, P <.0001). The Cox proportional hazards regression model identified that the variables most significantly associated with the transition to CAF were Ad (χ 2 =8.6, P =.003) and LP30 (χ 2 =5.1, P =.02), although significant differences in the left atrial dimension (40.8±5.3 versus 37.3±5.5 mm, P <.01) and the number of atrial premature contractions (3641±4524 versus 1489±2895 beats/d, P <.05) were observed between groups 1 and 2. Conclusions These results indicate that P-SAE could be useful to identify patients at risk for the transition from PAF to CAF.