Efficacy of cryoballoon ablation in patients with paroxysmal atrial fibrillation without time to pulmonary vein isolation assessment.

BACKGROUND: Real-time visualization of the electrical activity of the pulmonary veins (PV) is not always possible in the setting of atrial fibrillation (AF) cryoballoon ablation. We investigated the relation between the effective documentation of time to PV isolation and the clinical outcome in a cohort of patients with paroxysmal AF who underwent cryoballoon ablation. METHODS: One thousand forty two consecutive patients were enrolled. An inner lumen mapping catheter was typically used to visualize real-time electrical activity inside the PVs. RESULTS: Time to PV isolation was documented in all targeted PVs in 391 patients (Group 1), in 651 patients it was not possible to record PV potentials and assess time to PV isolation in at least one PV (Group 2). In Group 1 a longer procedure duration and ablation time were observed, while a longer fluoroscopy time was observed in Group 2. After a mean follow-up of 14 ±â€¯11 months, 209/1042 (20%) patients had an atrial arrhythmia recurrence (20.2% in Group 1, 19.9% in Group 2, p = 0.25). Complications occurred in 54/1042 (5.2%) patients without any difference among the two study groups. CONCLUSION: In our retrospective analysis, in about two thirds of patients undergoing cryoballoon ablation it was not possible to acutely assess time to PV isolation in all PVs. However, one-year freedom from clinically symptomatic atrial tachyarrhythmia was similar to that of patients in which time to PV isolation was documented in all targeted veins. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov (NCT01007474).

Assessment of spatial organization in the atria during paroxysmal atrial fibrillation and adrenergic stimulation.

Non-linear parameters were computed to assess the extent of spatial organization in the atria in terms of coupling/synchronization between electrograms recorded in different atrial sites. Recordings of 9 patients suffering from paroxysmal atrial fibrillation were tested during four clinical experimental conditions: sinus rhythm and atrial fibrillation, both before and after isoproterenol infusion, a drug mimicking adrenergic activation. Two non-linear metrics were investigated: an index of non-linear association (NLA) and a synchronization (S) index based on the cross-conditional entropy. Results evidence the presence of reduced coupling after drug infusion in both sinus rhythm and atrial fibrillation. Moreover, passing from the NLA to the S index, the capability of the parameter to capture the subtle changes due to isoproterenol administration increased.

Assessment of the dynamics of atrial signals and local atrial period series during atrial fibrillation: effects of isoproterenol administration.

BACKGROUND: The autonomic nervous system (ANS) plays an important role in the genesis and maintenance of atrial fibrillation (AF), but quantification of its electrophysiologic effects is extremely complex and difficult. Aim of the study was to evaluate the capability of linear and non-linear indexes to capture the fine changing dynamics of atrial signals and local atrial period (LAP) series during adrenergic activation induced by isoproterenol (a sympathomimetic drug) infusion. METHODS: Nine patients with paroxysmal or persistent AF (aged 60 +/- 6) underwent electrophysiological study in which isoproterenol was administered to patients. Atrial electrograms were acquired during i) sinus rhythm (SR); ii) sinus rhythm during isoproterenol (SRISO) administration; iii) atrial fibrillation (AF) and iv) atrial fibrillation during isoproterenol (AFISO) administration. The level of organization between two electrograms was assessed by the synchronization index (S), whereas the degree of recurrence of a pattern in a signal was defined by the regularity index (R). In addition, the level of predictability (LP) and regularity of LAP series were computed. RESULTS: LAP series analysis shows a reduction of both LP and R index during isoproterenol infusion in SR and AF (RSR = 0.75 +/- 0.07 RSRISO = 0.69 +/- 0.10, p < 0.0001; RAF = 0.31 +/- 0.08 RAFISO = 0.26 +/- 0.09, p < 0.0001; LPSR = 99.99 +/- 0.001 LPSRISO = 99.97 +/- 0.03, p < 0.0001; LPAF = 69.46 +/- 21.55 LPAFISO = 55 +/- 24.75; p < 0.0001). Electrograms analysis shows R index reductions both in SR (RSR = 0.49 +/- 0.08 RSRISO = 0.46 +/- 0.09 p < 0.0001) and in AF (RAF = 0.29 +/- 0.09 RAFISO = 0.28 +/- 0.08 n.s.). CONCLUSIONS: The proposed parameters succeeded in discriminating the subtle changes due to isoproterenol infusion during both the rhythms especially when considering LAP series analysis. The reduced value of analyzed parameters after isoproterenol administration could reflect an important pro-arrhythmic influence of adrenergic activation on favoring maintenance of AF.