ANALYSIS OF THE CARDIAC-RHYTHM PRECEDING EPISODES OF PAROXYSMAL ATRIAL-FIBRILLATION

Aims This study seeks to elucidate whether there was a common mode of initiation of paroxysmal atrial fibrillation (PAF) episodes that might suggest new therapies. Methods A library of 177 digitized and analyze d 24-hour Holter recordings from PAF pharmacotherapy trials was studie d. All noise-free PAF episodes greater than or equal to 0.5 minutes we re identified. PAF episodes and the preceding 2 minutes of sinus rhyth m were printed as tachograms and visually inspected. Heart rate and ec topic beat behavior were used to characterize modes of PAF onset by co mparing half-minute segments of the final 2 minutes of sinus rhythm. R esults Thirty-four recordings (from 19 patients, aged 61.7 +/- 11.5 ye ars) provided 231 PAF episodes suitable for analysis. No patients had a consistent mode of PAF onset. This was confirmed by systematic analy sis of the five patients with the most episodes. Overall, a highly sig nificant increase in ectopic beats, from 1.34 to 6.52 min(-1) (p < 0.0 01) was found, but heart rate did not significantly change (mean heart rate at onset = 64 beats/min). PAF was initiated by a solitary ectopi c bear in more than half of the cases. No consistent evidence for shor t-long-short sequences, seen in ventricular arrhythmias, was found. Co nclusion The mode of onset of atrial fibrillation is inconsistent, bot h across a population with PAF and within individuals. This has implic ations for understanding the mechanisms of atrial fibrillation onset i n human beings and for the treatment of the disorder.