DEPENDENCY ON ATRIAL ELECTROPHYSIOLOGICAL PROPERTIES OF APPEARANCE OFPAROXYSMAL ATRIAL-FIBRILLATION IN PATIENTS WITH WOLFF-PARKINSON-WHITE-SYNDROME - EVIDENCE FROM ATRIAL VULNERABILITY BEFORE AND AFTER RADIOFREQUENCY CATHETER ABLATION AND SURGICAL CRYOABLATION
Y. Muraoka et al., DEPENDENCY ON ATRIAL ELECTROPHYSIOLOGICAL PROPERTIES OF APPEARANCE OFPAROXYSMAL ATRIAL-FIBRILLATION IN PATIENTS WITH WOLFF-PARKINSON-WHITE-SYNDROME - EVIDENCE FROM ATRIAL VULNERABILITY BEFORE AND AFTER RADIOFREQUENCY CATHETER ABLATION AND SURGICAL CRYOABLATION, PACE, 21(2), 1998, pp. 438-446
The pathogenesis of paroxysmal atrial fibrillation in patients with Wo
lff-Parkinson-White syndrome and the effects of elimination of accesso
ry pathways on the appearance of atrial fibrillation are still controv
ersial. Fifty-four patients with Wolff-Parkinson-White syndrome were c
lassified into three groups: a No AF group (n = 24), patients without
paroxysmal atrial fibrillation; an RF-AF Group (n = 12), patients with
paroxysmal atrial fibrillation whose accessory path ways were elimina
ted using radiofrequency catheter ablation; and a Cryo-AF Group (n = 1
8), patients with paroxysmal atrial fibrillation whose accessory pathw
ays were eliminated with surgical cryoablation. The electrophysiologic
al characteristics of each group were evaluated prior to and following
the elimination of their accessory path ways. As indices of atrial vu
lnerability, the presence of fragmented atrial activity and repetitive
atrial firing zones were assessed, Inducibility of atrial fibrillatio
n was significantly reduced following ablation of accessory pathways i
n the Cryo-AF group (83.3%-5.6%, P < 0.0001), while it was unchanged i
n the RF-AF group (83.3%-75%). In preablation studies, the effective r
efractory periods of the atrium in the RF-AF group and the Cryo-AF gro
up was significantly shorter compared with the No AI; group (204 +/- 1
8 ms, 197 +/- 16 ms vs 246 +/- 44 ms, respectively, P < 0.0001). Follo
wing ablation, the effective refractory period for patients in the Cry
o-AF group was significantly prolonged compared with before ablation (
197 +/- 16 ms to 232 +/- 24 ms, P < 0.0001). As a result of this prolo
ngation of the effective refractory period of the atrium, the fragment
ed atrial activity and repetitive atrial response zones narrowed follo
wing ablation in the Cryo-AF group, but not in the RF-AF group. Theref
ore, the pathogenesis of atrial fibrillation in patients with Wolff-Pa
rkinson-White syndrome may depend on the refractory period of the atri
um rather than on the presence of accessory pathways.