Ablation therapies for paroxysmal atrial fibrillation: A systematic review and patient-level network meta-analysis

Introduction: Despite promising trials, catheter ablation is still regarded as an adjunct to antiarrhythmic drugs (AADs) in the treatment of paroxysmal atrial fibrillation (PAF). This study aimed to compare the effectiveness of various ablation therapies and AAD. Method: Randomised controlled trials or propensity score-matched studies comparing atrial tachyarrhythmia recurrence among any combination of ablation modalities or AAD were retrieved. Kaplan-Meier curves and risk tables for this outcome were graphically reconstructed to extract patient-level data. Frequentist network meta-analysis (NMA) using derived hazard ratios (HRs), as well as 2 restricted mean survival time (RMST) NMAs, were conducted. Treatment strategies were ranked using P-scores. Results: Across 24 studies comparing 6 ablation therapies (5,132 patients), Frequentist NMA-derived HRs of atrial fibrillation recurrence compared to AAD were 0.35 (95% confidence interval [CI]=0.25–0.48) for cryoballoon ablation (CBA), 0.34 (95% CI=0.25–0.47) for radiofrequency ablation (RFA), 0.14 (95% CI=0.07–0.30) for combined CBA and RFA, 0.20 (95% CI=0.10–0.41) for hot-balloon ablation, 0.43 (95% CI=0.15–1.26) for laser-balloon ablation (LBA), and 0.33 (95% CI=0.18–0.62) for pulmonary vein ablation catheter. RMST-based NMAs similarly showed significant benefit of all ablation therapies over AAD. The combination of CBA + RFA showed promising long-term superiority over CBA and RFA, while LBA showed favourable short-term efficacy. Conclusion: The advantage of ablation therapies over AAD in preventing atrial tachyarrhythmia recurrence suggests that ablation should be considered as the first-line treatment for PAF in patients fit for the procedure. The promising nature of several specific therapies warrants further trials to elicit their long-term efficacy and perform a cost-benefit analysis. Keywords: Atrial fibrillation, catheter ablation, network meta-analysis

Pulmonary vein isolation using multi-electrode radiofrequency vs conventional point-by-point radiofrequency ablation: A meta-analysis of randomized and non-randomized studies

Aims

Pulmonary vein isolation is effective in reducing atrial fibrillation (AF) episodes. Previous studies suggest single-shot techniques are effective and safe for this purpose. Procedural and clinical outcomes were compared between multi-electrode and point-by-point radiofrequency ablations by performing a meta-analysis of all randomized and non-randomized studies.

Methods and results

Systematic reviews of MEDLINE and Cochrane Library databases were performed. Studies comparing procedural (procedure and fluoroscopy times) and clinical (AF recurrence) outcomes were included in the meta-analysis. A total of 13 clinical studies (5 randomized and 8 non-randomized) including 2152 patients met the inclusion criteria. In patients underwent multi-electrode ablation, there were significant reductions in both total procedure and fluoroscopy times, compared with point-by-point ablation (mean difference = −34.3 min [95% CI (−50.1 to −18.5)], p < 0.001 and mean difference = −7.1 min [95% CI (−12.0 to −2.2)], p < 0.01, respectively). These significances also continued in patients with paroxysmal AF. No such difference was observed in regard to AF recurrence between the 2 ablation strategies (RR = 0.90 [95% CI (0.80–1.01)], p = 0.066). This insignificance was also observed in patients with paroxysmal AF.

Conclusions

In a heterogeneous AF population, multi-electrode ablation is as effective as point-by-point ablation, with better procedural and fluoroscopy durations.

One-Year Success Rate of Pulmonary Vein Isolation Using a Novel Irrigated Multipolar Mapping and Ablation Catheter With Reduced Power Settings

The use of a novel irrigated multipolar ablation and mapping catheter for pulmonary vein isolation in patients with atrial fibrillation (AF) has demonstrated reasonable acute success rates and short procedure times, however, long-term outcome data are limited. The aim of this study was to analyze the long-term efficacy of this novel ablation system utilizing a reduced power setting for safety purposes.A total of 89 patients with paroxysmal (63 of 89 patients; 71%) or persistent AF underwent PVI with a reduced power setting of maximum 20 Watts (W) unipolar radiofrequency energy and 30 seconds in duration. In cases of persistent AF, atrial substrate ablation was performed additionally. Follow-up was based on outpatient clinic visits at 3, 6, and 12 months and included 5-day Holter ECGs. All of the 347 identified pulmonary veins were successfully isolated. Mean procedure times in PVI and PVI plus substrate ablation were 102 ± 25 minutes and 126 ± 32 minutes, respectively, applying a mean total radiofrequency time of 14 ± 6 minutes and 19 ± 9 minutes. Mean fluoroscopy time was 17 ± 8 minutes and 18 ± 6 minutes, respectively. Follow-up was available for all 89 patients. At one-year follow-up, 44 (70%) patients with paroxysmal AF and 11 (42%) patients with persistent AF remained in stable sinus rhythm after a singleprocedure and off antiarrhythmic drugs.The use of a novel irrigated multipolar ablation catheter with a reduced power setting is safe and feasible, and demonstrates a one-year success rate of 70% in paroxysmal AF and 42% in persistent AF.

Multielectrode Pulmonary Vein Ablation Catheter (PVAC(®)): current data on results and risks

Electrical isolation of pulmonary veins is the cornerstone of catheter ablation for patients with symptomatic atrial fibrillation. However, uncertainty surrounds the choice of energy source in pulmonary vein isolation (PVI). Various alternative techniques such as the Pulmonary Vein Ablation Catheter (PVAC(®), Medtronic Inc., Minneapolis, MN, USA) have been developed to facilitate PVI. This over-the-wire multielectrode catheter is delivering duty-cycled bipolar and unipolar radiofrequency (RF) energy at relatively low power.PVI with this "one-shot" PVACatheter can shorten the procedure duration and lower fluoroscopy time compared to irrigated RF. It enables mapping and ablation with the same array, but fails to show signals during RF energy delivery. The effectiveness of PVAC is comparable to other technologies in randomized studies. The overall complication rate of PVAC PVI is comparable to irrigated RF and possibly slightly higher for cryoballoon PVI. Special attention has to be paid to an effective anticoagulation throughout the ablation procedure, avoidance of embolic events and pulmonary venous stenosis.The novel catheter design of the PVAC Gold(®) array may improve safety by reducing embolic events through avoidance of electrode 1-to-10 interaction and by better tissue contact due to the 20° forward tilt. Although clinical data with this new array are lacking so far, the PVAC system has been shown to be a promising tool for PVI. However, prospective studies especially with the novel array are required to determine its true role for catheter ablation of atrial fibrillation in the future.

Phased RF Ablation: Results and Concerns

Treatment of atrial fibrillation (AF) with catheter ablation has proven to be a safe and effective treatment modality which is offered to an increasing number of patients in many centers. Pulmonary vein isolation (PVI) is an established cornerstone of AF ablation strategies. Athough the isolation of the pulmonary veins (PVs) with irrigated focal radiofrequency (RF) catheters using a point-by-point method is considered as the gold standard, it can be challenging to create contiguous lesions, time consuming, and require advanced three dimensional (3D) mapping and navigational systems. The phased RF ablation system was designed to address many of these challenges associated with conventional focal RF ablation. In this review, we describe the main features of phased RF ablation and summarize the data available on clinical outcome with this technology.

Safety and efficacy of multipolar pulmonary vein ablation catheter vs. irrigated radiofrequency ablation for paroxysmal atrial fibrillation: a randomized multicentre trial

Aims

The current challenge in atrial fibrillation (AF) treatment is to develop effective, efficient, and safe ablation strategies. This randomized controlled trial assesses the medium-term efficacy of duty-cycled radiofrequency ablation via the circular pulmonary vein ablation catheter (PVAC) vs. conventional electro-anatomically guided wide-area circumferential ablation (WACA).

Methods and results

One hundred and eighty-eight patients (mean age 62 ± 12 years, 116 M : 72 F) with paroxysmal AF were prospectively randomized to PVAC or WACA strategies and sequentially followed for 12 months. The primary endpoint was freedom from symptomatic or documented >30 s AF off medications for 7 days at 12 months post-procedure. One hundred and eighty-three patients completed 12 m follow-up. Ninety-four patients underwent PVAC PV isolation with 372 of 376 pulmonary veins (PVs) successfully isolated and all PVs isolated in 92 WACA patients. Three WACA and no PVAC patients developed tamponade. Fifty-six percent of WACA and 60% of PVAC patients were free of AF at 12 months post-procedure (P = ns) with a significant attrition rate from 77 to 78%, respectively, at 6 months. The mean procedure (140 ± 43 vs. 167 ± 42 min, P<0.0001), fluoroscopy (35 ± 16 vs. 42 ± 20 min, P<0.05) times were significantly shorter for PVAC than for WACA. Two patients developed strokes within 72 h of the procedure in the PVAC group, one possibly related directly to PVAC ablation in a high-risk patient and none in the WACA group (P = ns). Two of the 47 patients in the PVAC group who underwent repeat ablation had sub-clinical mild PV stenoses of 25–50% and 1 WACA patient developed delayed severe PV stenosis requiring venoplasty.

Conclusion

The pulmonary vein ablation catheter is equivalent in efficacy to WACA with reduced procedural and fluoroscopy times. However, there is a risk of thrombo-embolic and pulmonary stenosis complications which needs to be addressed and prospectively monitored.

ClinicalTrials.gov Identifier

NCT00678340.