Electrophysiological characteristics of localized reentrant atrial tachycardia occurring after catheter ablation of long-lasting persistent atrial fibrillation.
ABSTRACT Mapping of recurrent atrial tachycardia (AT) after extensive ablation for long-lasting persistent atrial fibrillation (AF) is complex. We sought to describe the electrophysiological characteristics of localized reentry occurring after ablation of long-lasting persistent AF.
Out of 70 patients undergoing catheter ablation of long-lasting persistent AF, 9 patients (13%, 55 +/- 8 years, 8 males) in whom localized reentry was demonstrated in a repeat ablation were studied. Localized reentry was defined as reentry in which the circuit was localized to a small area and did not have a central obstacle. The mechanism of AT was determined by electroanatomical and entrainment mapping.
Nine localized reentries with cycle length of 243 +/- 41 ms were mapped in 9 patients. The location of AT was the left atrial appendage in 4 patients, anterior left atrium in 2, left septum in 2, and mitral isthmus in 1. In all ATs, a critical isthmus of <10 mm in width was identified in the vicinity of the prior linear lesions or ostia of isolated pulmonary veins. Ablation of the critical isthmus, which was characterized by continuous low-voltage activity (median voltage: 0.15 mV, mean duration: 117 +/- 31 ms), terminated AT and rendered it noninducible. Additionally, ablation was performed for all of inducible ATs. At 11 +/- 7 months after the procedure, 8 of 9 patients (89%) were free from any arrhythmias.
After ablation of long-lasting persistent AF, localized reentry may arise from a site in the vicinity of the prior ablation lesions. Ablation of the critical isthmus eliminates the arrhythmia.
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ABSTRACT: Radiofrequency ablation of focal atrial tachycardias (AT) is a validated technique with high success rates. However, electrophysiological (EP) characteristics and ablation strategy of localized reentrant AT originating from the coronary sinus ostium (CSo) have not been reported in detail so far. From January 2009 to July 2010, 1,453 patients underwent clinically motivated EP studies. Four patients were diagnosed with localized reentrant AT originating from the CSo. P wave morphology and consistency of tachycardia cycle length were studied. Subsequently, if reentry was suggested as an underlying mechanism for AT, color-coded 3-dimensional (3D) entrainment mapping was performed to localize the reentrant circuit or differentiate a localized reentrant AT from macroreentant AT, and also confirm reentry as an underlying mechanism of AT by evaluating consistency of return cycles after entrainment at multiple sites in both atria. Finally, activation mapping was performed to localize the earliest activation site. The P wave morphologies and isoelectric line between the P waves suggested most likely an AT originating from the CSo with a centrifugal activation pattern, which was confirmed by activation mapping. Consistency of return cycles and continuously fragmented local electrograms at successful ablation sites suggested reentry as an underlying AT mechanism. Color-coded 3D entrainment mapping in all 4 patients located the reentrant circuit in the CSo. There were also two specific features observed. One was fragmented and/or double potentials recorded in the CSo with prominent prolonged electrogram duration compared to those during sinus rhythm. The other is a significant conduction delay within the CS. The myocardium of the CSo was suggested as a part of the critical isthmus within the reentrant circuit, while the rest of atria distal to the CSo and myocardial coat of the distal CS were not involved in the tachycardia circuit, which was confirmed by entrainment mapping. Although CSo myocardium has been implicated to be a part of atrioventricular nodal reentrant tachycardia, to the best of our knowledge, this is the first report showing the localized reentrant AT confined to the CSo. Three of our patients (75%) had concomitant atrial fibrillation (AF). Further studies should be warranted to clarify the role of AT from the CS in triggering AF.Herzschrittmachertherapie & Elektrophysiologie 05/2012; 23(2):121-7.
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ABSTRACT: A low incidence of thromboembolic events after successful catheter ablation of atrial fibrillation (AF) during a mid-term follow-up period was recently reported. However, because the incidence of such events over the long term is unknown, we investigated the late incidence of thromboembolic events after catheter ablation. Patients with paroxysmal and persistent AF undergoing catheter ablation and being followed up for at least 24 months formed the study group (n = 524); 82 patients (16%) had CHADS₂ scores of at least 2. Mean follow-up was 44 ± 13 months. Warfarin was discontinued in 400 (93%) of 429 patients (82% of 524 patients) without AF recurrence. None of the patients without AF recurrence suffered thromboembolic events, whereas 3 of 95 patients (3%) with AF recurrence did (P < 0.001). One of the 3 was a late AF recurrence occurring > 12 months after catheter ablation. There were 2 nonfatal major hemorrhagic events in patients with AF recurrence who continued on warfarin, but no hemorrhagic events were observed in patients free from AF (P = 0.002). Maintenance of sinus rhythm after catheter ablation of AF was associated with a lower incidence of thromboembolic events during long-term follow-up >3 years. This result suggests that catheter ablation reduces thromboembolic events if patients continue anticoagulation regardless of the ablation outcome.Circulation Journal 07/2011; 75(10):2343-9. · 3.58 Impact Factor
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ABSTRACT: The efficacy of catheter-based ablation techniques to treat atrial fibrillation is limited not only by recurrences of this arrhythmia but also, and not less importantly, by new-onset organized atrial tachycardias. The incidence of such tachycardias depends on the type and duration of the baseline atrial fibrillation and specially on the ablation technique which was used during the index procedure. It has been repeatedly reported that the more extensive the left atrial surface ablated, the higher the incidence of organized atrial tachycardias. The exact origin of the pathologic substrate of these trachycardias is not fully understood and may result from the interaction between preexistent regions with abnormal electrical properties and the new ones resultant from radiofrequency delivery. From a clinical point of view these atrial tachycardias tend to remit after a variable time but in some cases are responsible for significant symptoms. A precise knowledge of the most frequent types of these arrhythmias, of their mechanisms and components is necessary for a thorough electrophysiologic characterization if a new ablation procedure is required.Cardiology research and practice. 01/2011; 2011:957538.