Long-term follow-up of changes in fibrillation waves in patients with persistent atrial fibrillation - Spectral analysis of surface ECG

Abstract

Background: Little is known about the shortening of atrial refractoriness as a result of electrical remodeling in atrial fibrillation (AF) in clinical cases, especially in terms of long-term follow-up, because of a lack of noninvasive testing methods. Methods and Results: The present study population comprised 38 consecutive patients with persistent AF (PAF, >1 month). Before and after the follow-up period of 1-14 months, surface ECGs were recorded for analysis. In each case, the fibrillation wave was purified by subtracting the QRS-T complex template and then power spectral analysis was performed. The mean fibrillation cycle length (FCL) and FCL coefficient of variation (FCL-CV) were determined from peak power frequency in 20 epochs in each recording. The change in FCL (ΔFCL) was calculated by subtracting the baseline FCL from the FCL after the follow-up period. To correct for the difference in the follow-up period, ΔFCL was divided by the follow-up period in each case. In 38 cases, mean FCL decreased from 160±20 ms to 151±19 ms (p<0.05), and the FCL-CV also decreased from 15±9% to 12±5% (p<0.05). The corrected ΔFCL was -2.4±7.6 (ms/month) and there was a significant negative correlation between corrected ΔFCL and baseline FCL (p<0.01). Conclusion: Shortening of the FCL during a relatively long-term follow-up period was observed in patients with PAF.