Quantitative analysis of circadian variation in atrial fibrillation frequency

In English Circadian variation in atrial fibrillation (AF) frequency
is explored in this paper by employing recent advances in
signal processing. Once the AF frequency has been estimated
and tracked by a hidden Markov model approach,
the resulting trend is analyzed for the purpose of detecting
and characterizing the presence of circadian variation.
With cosinor analysis, the results show that the shortterm
variations in AF frequency exceeds the variation that
may be attributed to circadian. Using the autocorrelation
method, circadian variation was detected in 13 of 18
ambulatory ECG recordings (Holter) acquired from patients
with long standing persistent AF. Using the ensemble
correlation method, the highest AF frequency usually occurred
during the afternoon, whereas the lowest usually
occurred during late night. It is concluded that circadian
variation is present in most patients with long standing
persistent AF but the short-term variation in AF frequency
is considerable.