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Background: The clinical significance of induced left atrial macro-reentrant tachycardia (LA-AT) after encircling pulmonary vein isolation (EPVI) is unclear. Our objective was to determine whether induced LA-ATs are associated with the clinical recurrence of ATs., Methods: We studied 185 consecutive patients with paroxysmal atrial fibrillation (PAF) who underwent their first EPVI with an 8-mm tip, nonirrigated catheter approach. AT was induced by atrial burst pacing after the completion of EPVI, and the atrial activation pattern was evaluated using EnSite NavX. Induced LA-ATs were ablated only in patients with clinical ATs of suspected LA origin. The factors associated with occurrence of AT after the procedure were examined., Results: LA-ATs were induced in 38 patients and ablated in 5 patients. During a follow-up of 23 ± 7 months, the occurrence of AT did not differ between patients with nonablated LA-ATs (4/33, 12 %) and those without any inducible ATs (16/113, 14 %, p > 0.99). In multivariate analysis, the number of ablation points for completing EPVI was the only independent predictor of AT occurrence (odds ratio 1.07, p < 0.01). A repeat procedure was performed in 22 of 26 patients who developed AT. Nineteen patients became free from AT and AF after ablation of the conduction gaps (EPVI, n = 17; another line, n = 4), extra PV firing (n = 4), focal AT (n = 4), and induced LA-ATs (n = 3)., Conclusions: In patients who had EPVI for PAF using an 8-mm tip, nonirrigated catheter, the occurrence of AT after EPVI was mainly due to conduction gaps in the ablation line or extra PV triggers. In patients with PAF, LA-ATs induced during the first procedure did not require ablation if they were not associated with clinical AT.

It is important to clarify how electrical remodeling develops in clinical cases of paroxysmal atrial fibrillation (PAF), because it has been suggested that this electrophysiological phenomenon promotes an increase in the frequency of PAF. In the present study, the f-f interval during PAF was analyzed from the ambulatory ECG recordings of 21 patients with PAF (total PAF duration >2/24 h with normal atrial size) to monitor the atrial electrophysiological changes. The patients were clinically followed-up for 6 months without any antiarrhythmic drugs. Before and after the follow-up period 24-h Holter monitoring was carried out and the duration of both the PAF and the f-f intervals during the PAF episode were evaluated. In selected cases, the atrial effective refractory period (ERP) was evaluated in an electrophysiologic study before and after the follow-up period. The total PAF duration was prolonged from 187+/-50 to 223+/-79 min (p=0.034) and the f-f interval was shortened from 0.14+/-0.03 to 0.12+/-0.02 ms (p=0.003). There was an inverse relationship between the changes in total PAF duration and f-f interval (p=0.027). The ERP was shortened from 214+/-15 to 194+/-5 ms (n=5, p=0.025) and there was a direct correlation between the changes in ERP and f-f interval (p=0.048). In clinical cases, the prolongation of the PAF was related to the shortening of the f-f interval during the PAF episodes and to the shortening of the atrial ERP. Electrical remodeling plays a role in promoting the development of the atrial fibrillation in patients with PAF.

Background: [corrected] Bepridil, a multiple ion-channel blocker, has been reported to prevent paroxysmal atrial fibrillation (PAF). The f-f interval of PAF during treatment with bepridil versus class Ic antiarrhythmic drugs was compared., Methods: Fifty-two patients with PAF were randomized to bepridil, 200 mg/day (n = 14) versus flecainide, 100 to 200 mg/day (n = 15) or pilsicainide, 75 to 150 mg/day (n = 23). The drug was considered effective when symptomatic episodes of PAF were decreased to < 50% during a follow-up of 2 to 6 months. The f-f interval was measured in 12-lead ECGs of initial PAF episodes., Results: Bepridil and Ic were effective in 10 of 14 (71.4%) and 24 of 38 patients (63.2%), respectively (ns). In the Ic group, the f-f interval was longer in successfully (114 +/- 48 ms) than in unsuccessfully (68 +/- 25 ms) treated patients (P = 0.002). In the bepridil group, the f-f interval was shorter in successfully (84 +/- 27 ms) than unsuccessfully (155 +/- 68 ms) treated patients (P = 0.015). When comparing unsuccessfully treated patients, the f-f interval in the bepridil group was significantly longer than in the Ic group (P = 0.007)., Conclusions: Bepridil was as effective as Ic drugs in the prevention of PAF. Because it was more effective in smaller (functional) than larger (anatomical) reentrant circuits, the effect of bepridil was considered to be mainly attributable to a class III antiarrhythmic action.

Bepridil, a multi-ion channel blocker, is effective for some types of cardiac arrhythmias, and so its effect on the paroxysmal atrial fibrillation (PAF) was evaluated in the present study, comparing it with class Ic antiarrhythmic drugs. The relationship between efficacy and the f-f interval in the surface ECG recording was also analyzed. Sixty-one symptomatic PAF patients were randomized to a bepridil group (200 mg/day, n=23) or class Ic drug group (flecainide 100-200 mg/day or pilsicainide 75-150 mg/day, n=38). The drug was considered effective for PAF prevention when symptomatic episodes of PAF were decreased to less than 50% during the follow-up period of 2-6 months. The f-f interval in the surface 12-lead ECG trace was evaluated during a PAF episode. Both bepridil and the class Ic drugs were effectively prevented PAF (15/23 (65.2%) vs 24/38 (63.1%) patients, NS). In the class Ic drug group, the f-f interval was longer in the effective cases (114+/-48 ms) than in the non-effective cases (68+/-26 ms, p=0.0002). In contrast, in the bepridil group the f-f interval was shorter in the effective cases (85+/-26 ms) than in the non-effective ones (152+/-45 ms, p=0.0005). When comparing the non-effective cases in the 2 groups, the bepridil group showed a significantly longer f-f interval than the class Ic drug group (p=0.0003). As a result of drug administration, the class Ic drugs prolonged the f-f interval from 78+/-33 ms to 128+/-46 ms (p=0.0004) whereas bepridil showed no change (109+/-39 ms vs 135+/-47 ms). For clinical PAF prevention, the effect of bepridil matched that of class Ic antiarrhythmic drugs. Because bepridil was effective in PAF patients with relatively shorter f-f intervals without prolonging the f-f interval, bepridil is considered to work mainly as a class III antiarrhythmic drug.