Atrial electrophysiological features in patients with Wolff-Parkinson-White and atrial fibrillation: absence of rate adaptation of intraatrial conduction time parameters

Effect of pulmonary vein isolation on atrial fibrillation recurrence after ablation of paroxysmal supraventricular tachycardia in patients with high dispersion of atrial refractoriness

PURPOSE

This study aimed to assess pulmonary vein isolation (PVI) efficacy on atrial fibrillation (AF) recurrence and to determine a predictive dispersion of atrial refractoriness (dERP) value for performing PVI in paroxysmal supraventricular tachycardia (PSVT) patients.

METHODS

Of 67 PSVT patients with past AF episodes who underwent accessory pathway (AP) or slow pathway of atrioventricular node ablation, 63 (4 lost to follow-up or death) were assigned into two groups (A and B; 29 and 34 patients, respectively) based on whether they underwent or not subsequent PVI, and all were followed-up up to 3 years. Atrial effective refractory period (AERP) and dERP were measured during the ablation procedure.

RESULTS

In receiver operating characteristic (ROC) curve analysis, dERP = 74.5 ms effectively predicted AF recurrence in PSVT patients (p = 0.003). Difference in AF recurrence rate between groups did not reach statistical significance (17.2%, 5/29 vs. 29.4%, 10/34, p = 0.203). AF recurrence rate was lower in patients with dERP >74.5 ms who underwent AP or slow-pathway ablation with vs. without PVI (18.2%, 2/11 vs. 77.8%, 7/9, p = 0.012).

CONCLUSIONS

PVI addition after successful AP or slow pathway of atrioventricular node ablation significantly reduced AF recurrence in PSVT patients with high atrial vulnerability (dERP >74.5 ms).

Atrial Fibrillation in the Wolff-Parkinson-White Syndrome

Since the advent of catheter ablation for atrial fibrillation (AF) aiming the pulmonary veins a few years ago, there has been an overwhelming interest and a dramatic increase in AF investigation. AF has a different dimension in the context of the Wolff-Parkinson-White (WPW) syndrome. Indeed, AF may be a nightmare in a young person that has an accessory pathway (AP) with fast anterograde conduction. It may be life-threatening if an extremely rapid ventricular response develops degenerating into ventricular fibrillation. Therefore, it is very important to know the mechanisms involved in the development of AF in the WPW syndrome. There are several possible mechanisms that may be involved in the development of AF in the WPW syndrome, namely, spontaneous degeneration of atrioventricular reciprocating tachycardia into AF, the electrophysiological properties of the AP, the effects of AP on atrial architecture, and intrinsic atrial muscle vulnerability. Focal activity, multiple reentrant wavelets, and macroreentry have all been implicated in AF, perhaps under the further influence of the autonomic nervous system. AF can also be initiated by ectopic beats originating from the pulmonary veins, and elsewhere. Several studies demonstrated a decrease incidence of AF after successful elimination of the AP, suggesting that the AP itself may play an important role in the initiation of AF. However, since AF still occurs in some patients with the WPW syndrome even after successful ablation of the AP, there should be other mechanisms responsible for the development of AF in the WPW syndrome. There is a clear evidence of an underlying atrial muscle disease in patients with the WPW syndrome. Atrial myocardial vulnerability has been studied performing an atrial endocardial catheter mapping during sinus rhythm, and analizing the recorded abnormal atrial electrograms. This review analizes the available data on this singular setting since AF has a reserved prognostic significance in patients with the WPW syndrome, and has an unusually high incidence in the absence of any clinical evidence of organic heart disease.

Electrophysiological characteristics of orthodromic reentrant tachycardia in patients with Wolf-Parkinson-White syndrome and atrial fibrillation

The aim of this study was to evaluate differences in the electrophysiological features of atrioventricular reentrant tachycardia (AVRT) in patients with Wolf-Parkinson-White syndrome (WPW) associated with or without atrial fibrillation (AF). We included 119 patients with WPW and orthodromic AVRT during electrophysiological study. The patients were divided into two groups; group I with documented episodes of AF (n=39, mean age 33.3+/-11.5 years), and group II without AF (n=80, mean age 35.3+/-13.8). We compared parameters of accessory pathway (AP), atrium and ventricle between two groups and found no significant difference. We next assessed the electrophysiological parameters of AVRT in both groups in terms of conduction times and atrioventricular (AV) activation relations. A significant negative correlation was found in group II between anterograde and retrograde conduction times measured as AV and VA intervals at the site of the earliest atrial activation (r=-0.43, P<0.0001), whereas no significant correlation was seen in group I (r=-0.29, P=0.1). Comparative analysis between two groups revealed significant difference in A-V/V-V index (P=0.05). These data suggest the presence of different electrophysiological properties of AP during AVRT in only few respects in patients with AF compared to those without it.

Evaluation of atrial vulnerability immediately after radiofrequency catheter ablation of accessory pathway in patients with Wolff-Parkinson-White syndrome

PURPOSE

The intrinsic atrial vulnerability is proposed as one of the mechanisms of paroxysmal atrial fibrillation (PAF) in Wolff-Parkinson-White (WPW) syndrome. In this study, we examined the early changes in atrial refractoriness and intra- and inter-atrial conduction times after radiofrequency (RF) catheter ablation of accessory pathway (AP).

METHODS

Twenty-four consecutive patients with WPW syndrome and documented AV reciprocating tachycardia but without history of PAF (fourteen male, mean age 39 +/- 9.5 years) and 27 control subjects (six female, mean age 51.4 +/- 10.1 years) with AV nodal reentrant tachycardia (AVNRT) who underwent ablation of the slow AV nodal pathways were enrolled into the study. Regional atrial effective refractory periods (AERPs), AERP dispersion, and intra- and inter-atrial conduction times were obtained before and 30 min after ablation and were compared between two groups. In the study group, patients with and without inducible AF were also compared regarding these parameters.

RESULTS

In the study group, AERPs in higher right atrium and right posterolateral atrium were significantly increased, and AERP dispersion, intra-atrial, and inter-atrial conduction times were significantly decreased after ablation; AERP in distal coronary sinus was unchanged. In control group, no significant difference was observed in these parameters. Inducibility of AF was significantly reduced following ablation of AP in the study group (from seven to zero of 24 patients, p = 0.016). Comparison between patients with (n = 7) and without (n = 17) AF revealed that left atrium diameter was larger, AERPs in the right posterolateral atrium before and after ablation, and ERP of AP were shorter in AF group.

CONCLUSION

In WPW syndrome patients, RF catheter ablation of AP results in an 'immediate' decrease in atrial vulnerability. Since inducibility of AF becomes more difficult in this less vulnerable atrium, the AP itself may play an important role in the development of AF.

Electrophysiological features of orthodromic atrioventricular reentry tachycardia in patients with wolff-Parkinson-white syndrome and atrial fibrillation

The aim of this study was to compare the electrophysiological features of tachycardia between WPW patients with and without AF. The study population consisted of 114 patients with WPW syndrome and reciprocating tachycardia during electrophysiological study. Two groups were selected: group I with AF during the procedure(n = 42)and the control group n = 72 without AF (group II). Cycle length (V-V interval), antero A-V, retrograde V-A conduction time during tachycardia and indexes V-A/V-V were analyzed. In addition, the relation between antero-, retrograde conduction time, and V-V was evaluated. Selection of the most predictive factor for AF presence was performed using regression analysis. Significant differences between the two groups were observed. These included a higher rate of tachycardia, shorter anterograde conduction time, A-V/V-V-indexes, longer retrograde conduction time, and V-A/V-V-indexes in group I compared with group II. Significant, positive correlations between anterograde conduction time and V-V were present in both groups, but retrograde conduction correlated significantly with the V-V-interval only in group II and group I (r = 0.37 vs r =-0.01, respectively). Significant, negative correlations between A-V and V-A conduction time in all analyzed points has been found to exist in group I (r =-0.45 for the point of maximal preexcitation [PMP]), whereas there were no significant correlations between these parameters in group II (r = 0.04). The most powerful AF predictor has been identified as the V-A/V-V index. The presence of AF in WPW syndrome may be associated with discrete patient characteristics. Ventricular activation occurs earlier, and atrial later, in the tachycardia cycle in AF than in patients free of AF. The different ability of the accessory pathway for adaptation to tachycardia rate changes in group I causes prolonged retrograde conduction over the pathway while the tachycardia rate increases.