Signal-averaged P-wave analysis of normal controls and patients with paroxysmal atrial fibrillation: a study in gender differences, age dependence, and reproducibility.

BACKGROUND: Atrial fibrillation is often first recognized after a complication such as embolic stroke has occurred. Limited data are available for the prospective identification of patients at risk for developing atrial fibrillation. HYPOTHESIS: Demonstration of areas of slow conduction in the atrium by means of P-wave signal averaging may identify individuals at risk for atrial fibrillation.
METHODS: P-wave signal averaging from the surface electrocardiogram was performed in 199 normal controls and 81 patients with paroxysmal atrial fibrillation using an automated, P-triggered, high-resolution signal for analysis.
RESULTS: Of the variables measured, the filtered P-wave duration and P-wave integral were significantly different between controls and patients (filtered P-wave duration 120 +/- 9 vs. 145 +/- 21 and P-wave integral 666 +/- 208 vs. 868 +/- 352), whereas the terminal root-mean-square (RMS) voltages (RMS 20, RMS 30, RMS 40) showed no significant differences between the two groups. Regression analysis of the first and second measurement of the filtered P-wave duration obtained during consecutive tests showed excellent reproducibility (r and r2 of 0.96 and 0.92). The duration of the filtered P wave showed no age dependence but was shorter in women.
CONCLUSION: Utilizing the 90th percentile value of the filtered P-wave duration of 133 ms in men and 130 ms in women, the sensitivity was 80 and 81%, the specificity 92 and 90%, the positive predictive value 84 and 73%, and the negative predictive value 90 and 93%, respectively.