Our Approach to Maximizing the Durability of Pulmonary Vein Isolation During a Paroxysmal Atrial Fibrillation Ablation Procedure

Safety and efficacy of steerable versus non-steerable sheaths for catheter ablation of atrial fibrillation systematic review and meta-analysis

OBJECTIVES

With the development of radiofrequency (RF) ablation technology. In recent years, more and more patients with atrial fibrillation (AF) have been treated with RF ablation. Steerable sheaths (SS) have been widely used in RF ablation of AF. The aim of this meta-analysis was to compare the efficacy and safety of AF ablation using SS and non-steerable sheaths (NSS).

METHODS

From the beginning to March 2022, we conducted a comprehensive, systematic search of the databases PubMed, MEDLINE, EMBASE, Web of Science and the Cochrane Library to finish the study. For categorical and continuous data, we used ORs and mean difference to calculate the effect. We also estimated the 95% CI.

RESULTS

Five studies of RF ablation of AF were selected, three prospective and two retrospective, involving 282 SS and 236 NSS ablation patients. The rate of recurrence of AF or atrial arrhythmias was 27.3% versus 42.8% (OR: 0.52, 95% CI 0.36, 0.76, z=3.41, p=0.0006) and acute pulmonary vein (PV) reconnection (8.7% vs 17.4%, OR: 0.47, 95% CI 0.23, 0.95, z=2.10, p=0.04). In the SS group and the NSS group, the total ablation time (p=0.25), fluoroscopy time (p=0.26) and total operative time (p=0.35) were not significantly different.

CONCLUSIONS

Compared with the use of NSS, the use of SS for RF ablation of AF can effectively reduce the recurrence rate of AF and the occurrence of acute PVs reconnection events. However, there is no advantage in shortening the total RF time, fluoroscopy time, total surgical time and reducing complications.

Efficacy of ablation index-guided pulmonary vein isolation in patients with paroxysmal atrial fibrillation

BACKGROUND

Ablation index (AI) is a novel technology of ablation lesion quality to help improve homogeneity of lesion size and continuity. In this study, we aim to evaluate whether AI-guided PVI improves clinical outcomes compared to CF-guided PVI in patients with paroxysmal AF (PAF).

METHODS

Patients undergoing first-time radiofrequency ablation for PAF were randomized in a 2:1 ratio to two groups: AI-guided PVI and CF-guided PVI. In the AI group, AI ≥500 was recommended at the anterior/superior/inferior walls, 350-400 at the posterior wall, and inter-lesion distance ≤4 mm. The primary endpoint is the freedom from atrial arrhythmia recurrence during 12 months follow-up, without antiarrhythmic drug therapy (ADT). The key secondary endpoints include intra-procedural efficiency and peri-procedural complications.

RESULTS

225 patients were randomized (AI group (n = 149) and CF group(n = 76)). First-pass isolation rate in AI group was significantly higher than that in CF group (58.3% vs. 43.4%, p = 0.035). After a median follow-up of 12.2 months, 154/225(68.4%) of patients were free from atrial arrhythmia recurrence without ADT, which was higher in AI group compared with CF group, but without significant difference (71.1% vs. 63.2%, p = 0.253). The incidence of peri-procedural complications is low and without difference between two groups.

CONCLUSIONS

AI-guided ablation provided higher acute efficacy than CF-guided ablation in PV isolation for patients with paroxysmal AF. The long-term success rate in AI group was higher than CF group, but did not reach statistical significance. This article is protected by copyright. All rights reserved.

Radiofrequency induced lesion characteristics according to force-time integral in experimental model

Contact force (CF)-sensing technology has enabled accurate real-time CF measurement in tissue. Average CF, which is quantified by the force–time integral (FTI), correlates with lesion volume. Little is known about which of the time and force factors that compose FTI plays a more important role and which is a better index for predicting lesion size, FTI, or force–power–time index (FPTI). Investigators sought to identify a better index for predicting radiofrequency ablation lesion formation with experimental model. Radiofrequency current was delivered to the swine skeletal muscle at radiofrequency energy current was delivered at 4 fixed power settings (15, 25, 30, and 40 W) for 6 variable time durations (5, 10, 20, 30, 40, and 50 s) with 6 variable CF settings (5, 10, 20, 30, 40, and 50 g). At each setting, the following parameters were evaluated: (1).. transmural lesion depth, (2).. lesion width, and (3).. lesion volume. Between FTI factors, the time factor was more important than the force factor for lesion formation. The area under the curve was greater for FPTI (0.943) than for FTI (0.870). On univariate linear regression analysis, the explanatory power of the linear regression model was better explained by FPTI (56.4%) than FTI (32.1%). Under the same FTI condition, the time factor had a greater effect on lesion formation. When power was included, the power factor had a greater effect on lesion formation and steam pop.

MEMS-Based Flexible Force Sensor for Tri-Axial Catheter Contact Force Measurement

Atrial fibrillation (AFib) is a significant healthcare problem caused by the uneven and rapid discharge of electrical signals from pulmonary veins (PVs). The technique of radiofrequency (RF) ablation can block these abnormal electrical signals by ablating myocardial sleeves inside PVs. Catheter contact force measurement during RF ablation can reduce the rate of AFib recurrence, since it helps to determine effective contact of the catheter with the tissue, thereby resulting in effective power delivery for ablation. This paper presents the development of a three-dimensional (3D) force sensor to provide the real-time measurement of tri-axial catheter contact force. The 3D force sensor consists of a plastic cubic bead and five flexible force sensors. Each flexible force sensor was made of a PEDOT:PSS strain gauge and a PDMS bump on a flexible PDMS substrate. Calibration results show that the fabricated sensor has a linear response in the force range required for RF ablation. To evaluate its working performance, the fabricated sensor was pressed against gelatin tissue by a micromanipulator and also integrated on a catheter tip to test it within deionized water flow. Both experiments simulated the ventricular environment and proved the validity of applying the 3D force sensor in RF ablation.

Central Sympathetic Inhibition: a Neglected Approach for Treatment of Cardiac Arrhythmias?

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Overactivation of the sympathetic nervous system (SNS) plays an important role in the pathogenesis of comorbidities related to AF such as hypertension, congestive heart failure, obesity, insulin resistance, and obstructive sleep apnea. Methods that reduce sympathetic drive, such as centrally acting sympatho-inhibitory agents, have been shown to reduce the incidence of spontaneous or induced atrial arrhythmias, suggesting that neuromodulation may be helpful in controlling AF. Moxonidine acts centrally to reduce activity of the SNS, and clinical trials indicate that this is associated with a decreased AF burden in hypertensive patients with paroxysmal AF and reduced post-ablation recurrence of AF in patients with hypertension who underwent pulmonary vein isolation (PVI). Furthermore, device-based approaches to reduce sympathetic drive, such as renal denervation, have yielded promising results in the prevention and treatment of cardiac arrhythmias. In light of these recent findings, targeting elevated sympathetic drive with either pharmacological or device-based approaches has become a focus of clinical research. Here, we review the data currently available to explore the potential utility of sympatho-inhibitory therapies in the prevention and treatment of cardiac arrhythmias.

Better Lesion Creation And Assessment During Catheter Ablation

Permanent destruction of abnormal cardiac tissue responsible for cardiac arrhythmogenesis whilst avoiding collateral tissue injury forms the cornerstone of catheter ablation therapy. As the acceptance and performance of catheter ablation increases worldwide, limitations in current technology are becoming increasingly apparent in the treatment of complex arrhythmias such as atrial fibrillation. This review will discuss the role of new technologies aimed to improve lesion formation with the ultimate goal of improving arrhythmia-free survival of patients undergoing catheter ablation of atrial arrhythmias.

Adenosine testing after second-generation cryoballoon ablation (ATSCA) study improves clinical success rate for atrial fibrillation

AIMS

Adenosine administration after pulmonary vein (PV) isolation using radiofrequency, laser, and cryoablation can cause acute recovery of conduction to the PVs and predict atrial fibrillation (AF) recurrence. This study evaluates whether ablation of dormant potentials post-adenosine administration following second-generation cryoballoon (CB-2G) ablation may improve the success rate for AF.

METHODS AND RESULTS

In 45 of 90 patients after a waiting period of 30 min, a bolus 15-21 mg of adenosine was administered followed by rapid saline flush. The response was assessed for each PV using a circular octapolar catheter. If needed, further ablation using a cryoballoon and/or cryocatheter was performed until no reconduction was observed after repeat adenosine administration. The remaining 45 patients did not receive adenosine after the procedure. Acute PV isolation was achieved in 352 of 358 PVs (98.3%) of 86 of 90 patients (95.6%) using CB-2G. The adenosine group showed dormant reconduction in 5 of 45 patients (11%), 8 of 179 PVs (4.5%), including 1 left superior pulmonary vein, 3 left inferior pulmonary vein, 1 right superior pulmonary vein, and 3 right inferior pulmonary vein. The success rate for adenosine and without adenosine group was 84 and 79%, respectively, after a mean follow-up of 397 ± 47 and 349 ± 66 days, without any AF recurrence in patients in whom adenosine-induced dormant conduction was ablated.

CONCLUSION

Adenosine testing after second-generation cryoballoon ablation study showed that reablation of initially isolated PVs increases the clinical success rate for AF.

Improvements In AF Ablation Outcome Will Be Based More On Technological Advancement Versus Mechanistic Understanding

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias. Catheter ablation has proven more effective than antiarrhythmic drugs in preventing clinical recurrence of AF, however long-term outcome remains unsatisfactory. Ablation strategies have evolved based on progress in mechanistic understanding, and technologies have advanced continuously. This article reviews current mechanistic concepts and technological advancements in AF treatment, and summarizes their impact on improvement of AF ablation outcome.

Electrophysiological Evaluation of Pulmonary Vein Isolation

Since the pulmonary veins (PVs) were identified as a major source of AF triggers, ablation strategies targeting the PVs have evolved from focal ablation inside the PVs to wide area circumferential PV isolation (PVI) which at this juncture is the standard approach. Despite the widespread popularity of PVI, a universal definition is lacking. While "entrance block" is a generally accepted endpoint for PVI, the role of "exit block" has yet to be determined. Inexcitability of the circular ablation line has been introduced as a promising additional endpoint for PVI and was associated with an improved clinical outcome in a randomized trial. Correct interpretation of PV electrograms during an ablation procedure is critical in terms of efficacy and safety. A variety of electrophysiological techniques help to correctly differentiate components of complex PV electrograms. Resumption of PV conduction after initially successful PVI leading to AF recurrence remains a major problem and confirmation of bi-directional conduction block does not exclude reversible tissue damage along the ablation line. Prolongation of post-PVI monitoring and application of provocative procedures such as the administration of adenosine after initial PVI to unmask dormant PV conduction may improve clinical outcome although there is lack of valid data supporting these strategies. This article aims on clarifying the electrophysiological criteria for complete pulmonary vein isolation and the explain the importance of this cornerstone in almost all atrial fibrillation ablation procedures.