Durability of cryothermal pulmonary vein isolation — Creating contiguous lesions is necessary for persistent isolation

Cryoablation Utilizing the KODEX-EPD Mapping System Versus Conventional Cryoballoon Ablation in the Management of Patients With Atrial Fibrillation: A Literature Review and Meta-Analysis

Atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia globally. AF is associated with different consequences, such as peripheral vascular embolism, stroke, dementia, heart failure, and death. Catheter ablation (CA) has become a reliable therapeutic option for symptomatic AF. Utilizing mapping systems in conducting cryoablation is supposed to improve pulmonary vein isolation (PVI) durability and overall treatment success rate. We performed a review of relevant articles. We formulated a search strategy as follows: (atrial fibrillation AND ("cryoballoon ablation" OR cryoablation) AND (KODEX-EPD AND KODEX OR mapping). Data were collected from Web of Science, PubMed, Cochrane Library, and SCOPUS databases. We assessed the efficacy, procedural characteristics, and safety of cryoablation using the KODEX-EPD mapping system versus conventional cryoablation. We demonstrated the superiority of cryoablation guided by the KODEX-EPD system as it was associated with a significantly lower recurrence rate after the procedure (RR = 0.61, P = 0.03). Furthermore, it allowed a significant reduction in the volume of contrast medium used during the procedure (MD = -20.46, P = 0.04) when compared to the conventional cryoablation. We found no significant difference between both procedures in terms of successful cryoballoon-based PVI (P = 1.00), procedural duration (P = 0.95), procedural complications (P = 0.607), fluoroscopic time (P = 0.36), and fluoroscopic dose (P = 0.16). The use of the novel KODEX-EPD mapping system in the cryoablation procedure was associated with a significant reduction of the volume of contrast medium use and the recurrence rate compared with the conventional cryoablation while preserving similar efficacy, safety profile, and procedure time.

One-year outcomes of wide antral cryoballoon ablation guided by high-density mapping vs. conventional cryoballoon ablation for atrial fibrillation: a propensity score-matched study

Background

Pulmonary vein isolation with wide antral ablation leads to better clinical outcomes for the treatment of atrial fibrillation, but the isolation lesion is invisible in conventional cryoballoon ablation. In this study, we aim to investigate the efficacy of the wide pulmonary vein isolation technique that includes the intervenous carina region, guided by high-density mapping, compared with pulmonary vein isolation alone without the mapping system.

Methods

We conducted a propensity score-matched comparison of 74 patients who underwent a wide cryoballoon ablation guided by high-density mapping (mapping group) and 74 controls who underwent conventional cryoballoon ablation in the same period (no-mapping group). The primary outcome was a clinical recurrence of documented atrial arrhythmias for >30 s during the 1-year follow-up.

Results

Of 74 patients in the mapping group, residual local potential in the pulmonary vein antrum was found in 30 (40.5%) patients, and additional cryothermal applications were performed to achieve a wide pulmonary vein isolation. Compared with the no-mapping group, the use of the mapping system in the mapping group was associated with a longer fluoroscopic time (26.97 ± 8.07 min vs. 23.76 ± 8.36 min, P = 0.023) and greater fluoroscopic exposure [339 (IQR181-586) mGy vs. 224 (IQR133-409) mGy, P = 0.012]. However, no significant differences between the two groups were found in terms of procedural duration and left atrial dwell time (104.10 ± 18.76 min vs. 102.45 ± 21.01 min, P = 0.619; 83.52 ± 17.01 min vs. 79.59 ± 17.96 min, P = 0.177). The rate of 12-month freedom from clinical atrial arrhythmia recurrence was 85.1% in the mapping group and 70.3% in the no-mapping group (log-rank P = 0.029).

Conclusion

Voltage and pulmonary vein potential mapping after cryoballoon pulmonary vein isolation can identify residual potential in the pulmonary vein antrum, and additional cryoablation guided by mapping leads to improved freedom from atrial arrhythmias compared with conventional pulmonary vein isolation without the mapping system.

Clinical Trial Registration Number

ChiCTR2200064383.

Clinical utility of the "balloon lever technique" in the right inferior pulmonary vein cryoballoon ablation

Background

The acute success rate of pulmonary vein isolation (PVI) with cryoballoon (CB) is reported to be lower in the right inferior pulmonary vein (RIPV). This study aimed to investigate the utility of the "balloon lever technique (BLT)" for RIPV CB ablation.

Methods

We retrospectively studied consecutive patients who underwent CB-PVI for atrial fibrillation between February 21, 2020 and June 3, 2022. RIPV cryoablation was performed according to a specific protocol. The patients underwent RIPV cryoablation using the conventional method. If the method was found ineffective, BLT cryoablation was performed. The acute success rate of RIPV CB ablation was examined. We also investigated the RIPV isolation rate and procedural parameters during conventional and BLT cryoablation.

Results

Ninety-three patients were included in the analysis. RIPV isolation was achieved in 89.2% (83/93) of the patients using conventional method and subsequent BLT cryoablation. Meanwhile, 68 patients underwent BLT cryoablation because the conventional method was ineffective. RIPV was isolated with BLT in 85.3% (58/68) of patients. Additionally, BLT was found to be superior to conventional cryoablation in terms of nadir balloon temperature, freezing time, and thawing time to a specific temperature in patients who underwent both conventional and BLT cryoablations.

Conclusions

BLT is useful in RIPV cryoablation when the conventional method is ineffective. BLT cryoablation may be helpful, mainly because of the BLT-mediated contact of the balloon with the bottom of the RIPV, which leads to optimal RIPV occlusion.

The Electrophysiology of Atrial Fibrillation: From Basic Mechanisms to Catheter Ablation

The electrophysiology of atrial fibrillation (AF) has always been a deep mystery in understanding this complex arrhythmia. The pathophysiological mechanisms of AF are complex and often remain unclear despite extensive research. Therefore, the implementation of basic science knowledge to clinical practice is challenging. After more than 20 years, pulmonary vein isolation (PVI) remains the cornerstone ablation strategy for maintaining the sinus rhythm (SR). However, there is no doubt that, in many cases, especially in persistent and long-standing persistent AF, PVI is not enough, and eventually, the restoration of SR occurs after additional intervention in the rest of the atrial myocardium. Substrate mapping is a modern challenge as it can reveal focal sources or rotational activities that may be responsible for maintaining AF. Whether these areas are actually the cause of the AF maintenance is unknown. If this really happens, then the targeted ablation may be the solution; otherwise, more rough techniques such as atrial compartmentalization may prove to be more effective. In this article, we attempt a broad review of the known pathophysiological mechanisms of AF, and we present the recent efforts of advanced technology initially to reveal the electrical impulse during AF and then to intervene effectively with ablation.

Pulmonary veins anatomical determinants of cooling kinetics during second-generation cryoballoon ablation

AIM

The aim of the study was to investigate the role of anatomical characteristics of the pulmonary veins (PVs) determining cooling kinetics during second-generation cryoballoon ablation (CbA).

METHODS AND RESULTS

we enrolled all consecutive patients who underwent CbA for symptomatic atrial fibrillation in our center from January 2019 to March 2019. All patients had complete computed tomography scans of the heart before the ablation. Anatomical characteristics were tested for prediction of a nadir temperature (NT) ≤ -48°C. Significant differences were noted among PV max diameter (20.8 ± 2.8 vs 18.5 ± 2.5 mm; P < .001); PV minimum diameter (15.2 ± 3.0 vs 13.0 ± 3.1 mm; P < .001); PV area (268.1 ± 71.9 vs 206.2 ± 58.7 mm² ; P < .001); PV ovality (1.4 ± 0.3 vs 1.5 ± 0.3; P = .005); and PV trunk length (27.4 ± 7.4 vs 21.3 ± 6.5 mm; P < .001). A scoring system was created by assigning one point each ranging from 0 (best anatomical combination) to 5. In the group with a score of 0, 94.0% of the CbA could reach a NT ≤ -48°C whereas with a score of 5, only 29.0% (P < .001). Left superior pulmonary vein with short trunk length and acute angle of PV branch was significantly associated with warmer NT (11.8% satisfactory CbA; P = .003). Regarding right inferior pulmonary vein, trunk length (P = .004), maximum diameter (P = .044), and transverse angle (P = .008) were independently associated with good NT.

CONCLUSION

Anatomical PV features are associated with cooling kinetics and an anatomical score could predict lower NT during second-generation CbA. Specific characteristics were identified for inferior PV. Although heart imaging is not mandatory prior CbA, it can be a useful tool to predict cooling kinetics.

Second-generation cryoballoon ablation for recurrent atrial fibrillation after an index procedure with radiofrequency versus cryo: Different pulmonary vein reconnection patterns but similar long-term outcome-Results of a multicenter analysis

INTRODUCTION

Repeated procedures are often needed for long-term success of atrial fibrillation ablation. There are scarce data regarding cryoballoon use for such procedure.

METHODS AND RESULTS

We analyzed acute effect and long-term follow-up of second-generation cryoballoon ablation, performed as a repeat procedure after an index radiofrequency vs cryoballoon ablation. Sixty-one patients from three centers were included. In 36 cases radiofrequency (RF-I) and in 25 cryoballoon ablation (CB-I) was the index procedure. During redo procedure, pulmonary vein reconnection was less frequent in CB-I vs RF-I (51.5% vs 66.9%; P = 0.017). After cryoballoon, left inferior (P =  0.027) and right superior (P = 0.06) pulmonary veins were less likely to exhibit reconnection. Moreover, patients after initial RF ablation frequently presented multiple-vein reconnection (P = 0.018), while patients after cryoablation more often had only one vein reconnected (P = 0.008). During reablation procedures, all 149 reconnected veins in both groups were isolated, with no differences in procedural parameters, except for procedure time, shorter in CB-I group (65.5 vs 71.1 minutes; P = 0.04). Transient phrenic nerve palsy was the only complication in both groups (5.6% and 8.0%; ns). After mean follow-up of 15 ± 9 months, 70.3% of patients were free from atrial fibrillation (AF), with no differences between the groups (P = 0.71). In multivariate Cox-regression analysis, the persistent form of arrhythmia (P = 0.009) and relapse in the blanking period (P = 0.0004) were the only independent predictors of AF recurrence.

CONCLUSIONS

The use of second-generation cryoballoon is associated with less frequent pulmonary vein reconnection compared with RF ablation. Cryoballoon is safe and effective for repeated AF ablation, regardless of the technique used for the initial procedure.

Second-generation cryoballoon ablation for recurrent atrial fibrillation after an index cryoballoon procedure: a staged strategy with variable balloon size

PURPOSE

Currently, information on the optimal approach of redo procedures for paroxysmal atrial fibrillation (PAF) is limited. Radiofrequency ablation is the preferred technique, with reported success rates of 50-70% at 1-2 years, whereas only few reports exist on redo cryoballoon (CB) ablations. We describe outcomes on a systematic approach of repeat procedures with a second-generation cryoballoon (CB-2) after a successful index CB ablation.

METHODS

Cohort study of 40 consecutive patients with recurrent PAF (55% male), median CHA2DS2-VASc score 1 (IQR 0-3). Per protocol, a staged variable balloon size strategy was followed with a different balloon size during the redo as compared to the index procedure. Minimal follow-up was 12 months (median 17 months [IQR 14-39]).

RESULTS

Overall, 120 pulmonary veins (PVs) (75%) showed chronic isolation: 64% (41/64) for first-generation cryoballoon (CB-1) and 82% (79/96) for CB-2 index procedures, respectively (p = 0.01). The overall mean number of reconnected PVs per patient was 1.0 (40/40): 1.4 for CB-1 and 0.7 for CB-2 index procedures (p = 0.008). Phrenic nerve palsies (n = 7) resolved before the end of the procedure. At 1 year, 70% of patients were free of recurrent AF. In multivariate analysis, the only independent predictor of recurrence was the number of prior cardioversions.

CONCLUSIONS

A systematic approach of repeat procedures with a CB-2 using a different balloon size than during the index CB ablation is safe, with acceptable 1-year outcomes. Future comparative studies on the optimal redo technique and approach are warranted to further improve rhythm control in AF.

Atrial fibrillation: review of current treatment strategies

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in modern clinical practice, with an estimated prevalence of 1.5-2%. The prevalence of AF is expected to double in the next decades, progressing with age and increasingly becoming a global medical challenge. The first-line treatment for AF is often medical treatment with either rate control or anti-arrhythmic agents for rhythm control, in addition to anti-coagulants such as warfarin for stroke prevention in patient at risk. Catheter ablation has emerged as an alternative for AF treatment, which involves myocardial tissue lesions to disrupt the underlying triggers and substrates for AF. Surgical approaches have also been developed for treatment of AF, particularly for patients requiring concomitant cardiac surgery or those refractory to medical and catheter ablation treatments. Since the introduction of the Cox-Maze III, this procedure has evolved into several modern variations, including the use of alternative energy sources (Cox-Maze IV) such as radiofrequency, cryo-energy and microwave, as well as minimally invasive thoracoscopic epicardial approaches. Another recently introduced technique is the hybrid ablation approach, where in a single setting both epicardial thoracoscopic ablation lesions and endocardial catheter ablation lesions are performed by the cardiothoracic surgeon and cardiologist. There remains controversy surrounding the optimal approach for AF ablation, energy sources, and lesion sets employed. The goal of this article is review the history, classifications, pathophysiology and current treatment options for AF.