Role of the notched unipolar electrogram in guiding catheter ablation of frequent premature ventricular contractions originating from the ventricular outflow tract.

OBJECTIVE: To investigate the value of a notched unipolar electrogram (N-uniEGM) in confirming the origin of premature ventricular contractions originating from the ventricular outflow tract (VOT-PVC) during mapping and ablation procedures. METHODS: This retrospective study enrolled consecutive patients with symptomatic idiopathic frequent VOT-PVCs that underwent radiofrequency ablation. The characteristics of the uniEGM of the successful ablation targets were analysed. N-uniEGM was defined as the uniEGM presenting a QS morphology with ≥1 steep notches on the downstroke deflection. All patients were followed-up for 3 months post-ablation. RESULTS: The study enrolled 190 patients with a mean ± SD age of 49.0 ± 15.3 years. N-uniEGMs were recorded in 124 of 190 (65.3%) patients. The N-uniEGM distribution area was limited to a mean ± SD of 0.8 ± 0.4 cm2. N-uniEGM showed consistency with the outcomes of activation mapping and pace mapping. Patients with an N-uniEGM had an ablation success rate of 98.4% (122 of 124) and their ablation times were significantly shorter than those without an N-uniEGM (7.6 ± 3.8 s versus 15.8 ± 8.8 s, respectively). The sensitivity and specificity of N-uniEGM in predicting successful ablation of VOT-PVCs were 72.6% and 91.7%, respectively. CONCLUSION: N-uniEGM was a highly specific and moderately sensitive predictor of successful radiofrequency ablation in patients with VOT-PVCs.

Pace capture and adenosine triphosphate provocation are complementary rather than mutually exclusive methods to ensure durable pulmonary vein isolation.

INTRODUCTION: Adenosine triphosphate (ATP)-provoked dormant conduction (DC) and pacing for unexcitability are used to identify conduction gaps along the ablation lines after circumferential pulmonary vein isolation (CPVI). We aim to determine whether ATP provocation and pacing are interchangeable as endpoints for ablation of paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: A total of 107 patients with PAF were randomly divided into two groups after completion of CPVI. In group I (A-P group, n = 53), ATP was administered first. If DC was uncovered, additional ablation was performed until ATP tests were negative. Bipolar pacing along the ablation line was performed subsequently. In group II (P-A group, n = 54), the same protocol was used, but the pacing and the ATP tests were performed in the opposite sequence. The 12-month ablation outcomes of all patients were compared with those of a historical control group of 107 patients with PAF in whom only ATP test was performed. Regardless of which test was performed first, the other modality still identified conduction gaps. In group I, pacing maneuvers identified gaps in 49% (n = 26) of patients who had negative ATP tests. In group II, ATP tests uncovered DC in 18.5% (n = 10) of patients in whom pacing identified no gaps. After 12 months, a higher proportion of patients (91.6%) were free from atrial tachyarrhythmias compared with the historical control group (81.3%; P = 0.031). CONCLUSION: Pacing along the ablation lines and ATP provocation are complementary tests for evaluating the durability of CPVI and can lead to better long-term outcomes when used in combination.

Low-Dose Ibutilide Combined with Catheter Ablation of Persistent Atrial Fibrillation: Procedural Impact and Clinical Outcome.

BACKGROUND: In patients with persistent atrial fibrillation (AF), the procedural and clinical outcomes of ablation combined with infusion of antiarrhythmic drug are unknown. OBJECTIVES: To determine the impact of low-dose ibutilide after circumferential pulmonary vein isolation (CPVI) and/or left atrial (LA) substrate modification on acute procedural and clinical outcome of persistent AF. METHODS: In a prospective cohort of 135 consecutive patients with persistent AF, intravenous 0.25 mg ibutilide was administered 3 days before the procedure and intraprocedurally, if required, after CPVI and/or additional LA substrate modification of sites with continuous, rapid or fractionated, and low-voltage (0.05-0.3 mv) atrial activity. RESULTS: Persistent AF was terminated by CPVI alone (n=15) or CPVI + ibutilide (n=32) in 47 (34.8%) patients (CPVI responders). Additional LA substrate modification without (n=33) or with subsequent administration of 0.25 mg ibutilide (n=19) terminated AF in another 52 (38.5%) patients (substrate modification responders). Sinus rhythm was restored by electrical cardioversion in the remaining 36 (26.7%) patients (nonresponders). The mean LA substrate ablation time was 14 ± 6 minutes. At follow-up of 24 ± 10 months, the rates of freedom from atrial tachyarrhythmias among the responders in CPVI and substrate modification groups were mutually comparable (66.0% and 69.2%) and higher than among the nonresponders (36.1%; P < 0.01). Among the responders, there was no difference in clinical outcome between patients whose persistent AF was terminated without or with low-dose ibutilide. CONCLUSION: Administration of low-dose ibutilide during ablation of persistent AF may allow select patients wherein substrate ablation is not or minimally required to optimize procedural and clinical outcomes.

The safety and efficacy of hybrid ablation for the treatment of atrial fibrillation: A meta-analysis.

INTRODUCTION: Hybrid ablation, an emerging therapy that combines surgical intervention and catheter ablation, has become a viable option for the treatment of persistent atrial fibrillation. In this analysis, we aimed to evaluate the safety and efficacy of hybrid ablation, as well as compare the outcomes of one-step and staged approaches. METHODS: We conducted a search in major online databases and selected the studies that met the inclusion criteria. The primary endpoint was defined as no episode of atrial fibrillation or atrial tachycardia lasting longer than 30 seconds without administration of antiarrhythmic drugs. RESULTS: Sixteen studies including 785 patients (paroxysmal atrial fibrillation, n = 83; persistent atrial fibrillation, n = 214; long-standing persistent atrial fibrillation, n = 488) were selected. Average history of atrial fibrillation was (5.0±1.6) years. The pooled proportion of patients who were arrhythmia-free at the primary endpoint was 73% (95% CI, 64%-81%, Cochran's Q, P<0.001; I2 = 81%). The pooled rate of severe short-term complications was 4% (95% CI, 2%-7%, Cochran's Q, P = 0.01; I2 = 51%). The success rate after one-step procedures (69%) was lower than that after staged procedures (78%). The staged approach could ultimately prove to be safer, although complication rates were relatively low for both approaches (2% and 5%, respectively). CONCLUSIONS: Hybrid ablation is an effective and generally safe procedure. The current data suggest that staged hybrid ablation could be the optimal approach, as it is associated with a higher success rate and a seemingly lower complication rate. Additional randomized controlled trials are necessary to confirm these results.

Catheter ablation of persistent atrial fibrillation with and without a history of paroxysmal atrial fibrillation.

BACKGROUND: It is unclear whether a history of paroxysmal atrial fibrillation (PAF) would impact the effect of catheter ablation on persistent atrial fibrillation (AF). This study aimed to compare the effect of catheter ablation on persistent AF with and without a history of PAF. METHODS: One hundred and eighty-three patients underwent catheter ablation of persistent AF lasting for > 1 month and were reviewed. Patients were divided into two groups according to whether they had a history of PAF or not. Group I consisted of persistent AF patients with a history of PAF, and group II consisted of persistent AF patients without such a history. All patients received catheter ablation focused on pulmonary vein isolation and were observed for arrhythmia recurrences, which were defined as documented episodes of AF or atrial tachycardia after a blanking period of 3 months. RESULTS: One hundred and three patients (60.9%) in group I and sixty-six patients (39.1%) in group II were successfully followed and included in analysis. There were no significant differences in clinical and echocardiographic characteristics between both groups except for a younger age and more male patients in group II. After (15.5 ± 10.7) months of follow-up, 59 (57.3%) patients in group I and 49 (74.2%) patients in group II maintained sinus rhythm free of anti-arrhythmia drugs (P = 0.025). Multivariate analyses found left atrial anteroposterior diameter (P = 0.006) and persistent AF with a history of PAF (OR 1.792, 95%CI 1.019 - 3.152; P = 0.043) as the only independent statistical predictors of arrhythmia recurrences. CONCLUSION: The arrhythmia recurrence rate of catheter ablation based on pulmonary vein isolation in persistent AF with a history of PAF was higher than those without a history of PAF.

Epicardial isolation of pulmonary veins with ethanol in open chest dogs.

BACKGROUND: Radiofrequency (RF) ablation has become a widely accepted treatment for atrial fibrillation (AF). This study aimed to identify the efficacy and safety of pulmonary vein (PV) ablation with ethanol and to explore an alternative energy source for catheter ablation of AF. METHODS: Twelve open-chest mongrel dogs were randomized into ethanol ablation group and control group. Both the injections and electrophysiological mapping procedures were performed epicardialy. In ethanol ablation group (n = 6), injections were performed to circumferentially ablate the root of each PV (0.2 ml each site, 3 mm apart) with 95% ethanol using an 1 ml injector. In control group (n = 6), saline was injected other than ethanol. PV isolation was confirmed with a circular catheter immediately after the procedure and at follow up of 30 days. PV isolation was defined as the absence of PV potentials at each electrode of the circular catheter positioned at the PV side of the lesions, as well as complete conduction block into left atrium (LA) during PV pacing. RESULTS: PV electrical isolation with complete bidirectional conduction block was achieved with ethanol immediately and at 30 days in 95% of PVs, while saline injection caused only transient conduction changes between LA and PVs. In ethanol group, histologic analysis showed transmural lesions at 30 days. And there was no evidence of PV stenosis or thrombus formation. Mean LA diameter was not significantly different between baseline and 30 days. CONCLUSION: Ethanol is a safe energy source to effectively isolate PV in canine model and may be promising in endocardial ablation procedure of AF patients in the future.

Additional ablation of complex fractionated atrial electrograms after pulmonary vein isolation in patients with atrial fibrillation: a meta-analysis.

BACKGROUND: The efficacy of additional complex fractionated atrial electrogram (CFAE) ablation after pulmonary vein antrum isolation (PVAI) in patients with atrial fibrillation (AF) remains controversial. This meta-analysis was performed to assess the additional efficacy of CFAEs ablation after a single procedure without antiarrhythmic drugs. METHODS AND RESULTS: Trials were identified in MEDLINE, Cochrane Library, Embase, Google Scholar, reviews, and reference lists of relevant papers. Controlled cohort studies comparing the long-term efficacy of combined CFAEs plus PVAI ablation with PVAI alone were included. The primary end point was the maintenance of sinus rhythm without antiarrhythmic drugs. Seven controlled trials (9 comparisons) with a total of 622 participants (332 patients underwent PVAI plus CFAE ablation and 330 patients underwent PVAI alone) were included in the meta-analysis. In an overall pooled estimate, compared with PVI alone, long-term rates of sinus rhythm maintenance (relative risk, 1.17, 95% confidence interval, 1.03 to 1.33, P=0.019) were increased by additional CFAE ablation. Subgroup analysis demonstrated that additional CFAEs ablation increased rates of sinus rhythm maintenance in nonparoxysmal AF (relative risk, 1.35; 95% confidence interval, 1.04 to 1.75; P=0.022), whereas had no effect on patients with paroxysmal AF (relative risk, 1.04; 95% confidence interval, 0.92 to 1.18; P=0.528). CONCLUSIONS: Adjuvant CFAE ablation in addition to standard PVAI increases the rate of long-term sinus rhythm maintenance in nonparoxysmal AF patients after a single procedure without antiarrhythmic drugs but does not provide additional benefit to sinus rhythm maintenance in paroxysmal AF patients.

Ablation of right-sided accessory pathways with atrial insertion far from the tricuspid annulus using an electroanatomical mapping system.

BACKGROUND: It is difficult to ablate a right-sided accessory pathway (AP) with atrial insertion far from the tricuspid annulus (TA). We report our initial experience of ablating this rare AP by a 3-dimensional electroanatomical mapping system (CARTO). METHODS: From January of 2006 to April of 2008, 18 patients with right-sided APs who failed previous outside ablations were enrolled in this study. Retrograde AP conduction was mapped during pacing at the right ventricular apex by activation-mapping the right atrium (RA) using a 3-dimensional electroanatomical mapping system. AP atrial insertion was defined as the earliest retrograde atrial activations and successful ablation of the APs at this site. RESULTS: Among the 18 patients who had failed previous ablation, 10 patients (7 patients with right manifest APs and 3 patients with right conceal APs) had atrial insertions far from the TA. Of the 10 patients, the atrial insertions were found at the base of the RA appendage in 3 patients, at the high lateral RA in 5 patients, at the low lateral RA in other 2 patients. Ablation at the atrial insertions successfully abolished the AP conduction. The mean distance between the atrial insertion sites and the TA was 20.2 ± 2.7 mm. No patients reported recovered AP conduction or recurrent tachycardias after 6-month follow-up. CONCLUSIONS: The right-sided APs may have atrial insertion far from the TA. These uncommon variation of APs can be reliably identified and ablated using CARTO system.