OBJECTIVES We investigated the electrophysiologic characteristics in the in
itiation of paroxysmal atrial fibrillation (PAF) from a focal area.
BACKGROUND The electrophysiologic characteristics in the initiation of PBF
are still not clear.
METHODS The study group consisted of 77 patients (M/F = 65/12, age 66 +/- 1
2 years) with frequent episodes of PAF; we analyzed: 1) 15 cycle lengths of
electrical activity before the onset of atrial fibrillation (AF); 2) coupl
ing interval (CI) of the first ectopic beat just before the initiation of A
F: and 3) the prematurity; of an ectopic beat (prematurity index [PI] = CI/
mean of preceding 15 cycle lengths).
RESULTS A total of 111 episodes of sustained AF were identified, Two patter
ns of AF initiation were observed: group I (59/111, 53%) included the episo
des preceded bu cycle length oscillation, and group II (52/111, 47%) includ
ed the episodes initiated by a single ectopic beat with preceding cycle. le
ngth relatively constant. The PI of group I episodes was significantly grea
ter than that of group II (0.41 +/- 0.12 vs. 0.34 +/- 0.10, p < 0.01). The
CI (267 +/- 54 ms vs. 217 +/- 55 ms, p < 0.05), AF1 (194 +/- 36 ms rs. 153
+/- 37 ms, p < 0.05) and PI (0.49 +/- 0.13 ts. 0.37 +/- 0.11, p < 0.01) of
the AF episodes from the superior vena cava (SVC) were significantly longer
and greater than those of AF episodes from pulmonary veins (PVs).
CONCLUSIONS In patients with PAF originating from PVs or the SVC, two major
initiating patterns were found. Moreover, the electrophysiologic character
istics in the initiation of AF originating from the SVC were also different
from those of AF initiating from the PVs. (J Am Coll Cardiol 2001;37:1658-
64! (C) 2001 by the,American College of Cardiology.