The Hot and the Cold: Radiofrequency Versus Cryoballoon Ablation for Atrial Fibrillation

Feasibility of double-blinded, placebo-controlled interventional study for assessing catheter ablation efficacy in persistent atrial fibrillation: Insights from the ORBITA AF feasibility study

BACKGROUND

To date, there are no randomized, double-blinded clinical trials comparing catheter ablation to DC cardioversion (DCCV) with medical therapy in patients with persistent atrial fibrillation (PersAF). Conducting a large-scale trial to address this question presents considerable challenges, including recruitment, blinding, and implementation. We conducted a pilot study to evaluate the feasibility of conducting a definitive placebo-controlled trial.

METHODS

This prospective trial was carried out at Barts Heart Centre, United Kingdom, employing a randomized, double-blinded, placebo-controlled design. Twenty patients with PersAF (duration <2 years) were recruited, representing 10% of the proposed larger trial as determined by a power calculation. The patients were randomized in a 1:1 ratio to receive either PVI ± DCCV (PVI group) or DCCV + Placebo (DCCV group). The primary endpoint of this feasibility study was to evaluate patient blinding. Patients remained unaware of their treatment allocation until end of study.

RESULTS

During the study, 35% of patients experienced recurrence of PersAF prior to completion of 12 months follow-up. Blinding was successfully maintained amongst both patients and medical staff. The DCCV group had a trend to higher recurrence and repeat procedure rate compared to the PVI group (recurrence of PersAF 60% vs 30%; p = .07 and repeat procedure 70% vs 40%; p = .4). The quality of life experienced by individuals in the PVI group showed improvement, as evidenced by enhanced scores on the AF specific questionnaire (AF PROMS) (3 [±4] vs 21 [±8]) and SF-12 mental-component raw score (51.4 [±7] vs 43.24 [±15]) in patients who maintained sinus rhythm at 12 months.

CONCLUSION

This feasibility study establishes the potential for conducting a blinded, placebo-controlled trial to evaluate the efficacy of PVI versus DCCV in patients with PersAF.

Atrial Flutter in the Elderly Patient: The Growing Role of Ablation in Treatment

The prevalence of atrial flutter (AFL) is increasing among the elderly population, and managing this condition presents specific challenges within this demographic. As patients age, they often exhibit reduced responsiveness to conservative treatment, necessitating a more invasive approach. We present a case of a 93-year-old female who presented to the hospital with acute decompensated heart failure (ADHF) and AFL. A year prior, she was diagnosed with arrhythmia-induced cardiomyopathy. Despite recovering her ejection fraction (EF) through guideline-directed medical therapy (GDMT), her EF deteriorated again. The patient declined invasive management for her arrhythmia on multiple occasions. Managing such patients is challenging since the approach with pharmacotherapy alone often fails to maintain sinus rhythm or adequately control the ventricular rate. Growing evidence shows that invasive management, especially ablation, may be a safe and effective procedure for this patient population. Furthermore, the studies suggest that ablation may yield particular benefits for patients with simultaneous heart failure and atrial fibrillation/AFL (AF/AFL). Unfortunately, limited data exist regarding the invasive management of AFL in the elderly. Therefore, this case report aims to provide a comprehensive review of the current evidence regarding the safety and efficacy of ablation as a therapeutic option for AFL in elderly patients, with a particular focus on how patients with concomitant heart failure may benefit from ablation.

Catheter Ablation Energy Sources and Myocardial Injury and Coagulation Biomarkers During Uninterrupted Periprocedural Edoxaban Use - A Subanalysis of KYU-RABLE

BACKGROUND

The effects of catheter ablation (CA) energy sources on myocardial injury and coagulation biomarkers among Japanese non-valvular atrial fibrillation patients receiving uninterrupted periprocedural edoxaban are unclear. This KYU-RABLE exploratory subanalysis compared the effects of CA using radiofrequency energy vs. cryoballoon on: (1) myocardial injury; and (2) plasma edoxaban and coagulation biomarker concentrations measured before and after CA.Methods and Results:Plasma creatine kinase (CK), edoxaban, D-dimer, and prothrombin fragment 1+2 (F1+2) concentrations within 1 h before CA were compared with concentrations the day after. All biomarkers increased after CA, regardless of the energy source, but especially with cryoballoon. Significantly higher increases in CK concentrations from before to the day after CA were seen with cryoballoon compared with radiofrequency energy (P<0.0001). Edoxaban concentrations were similar in both groups. Concentrations of D-dimer and F1+2 increased in both groups, but were significantly higher in the cryoballoon group (P<0.0001 and P=0.006, respectively). There were no significant between-group differences in the incidence of thrombotic or bleeding events.

CONCLUSIONS

Uninterrupted edoxaban concentrations were similar in both groups. Both myocardial injury and coagulation biomarkers increased after CA, especially with cryoballoon, but there was no difference in the incidence of thrombotic or bleeding events. These findings suggest the efficacy of uninterrupted edoxaban, regardless of the CA energy source. Periprocedural anticoagulation, particularly with cryoballoon, should be undertaken with care.

Early markers of atrial fibrillation recurrence after pulmonary vein isolation

BACKGROUND

Postprocedural atrial extrasystole (AES) frequency predicts atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) in patients with paroxysmal AF. However, the predictive value of preprocedural AES frequency is unknown. We investigate whether preprocedural AES frequency is a feasible marker to predict (timing of) AF recurrence after PVI.

METHODS

Patients (N = 684) with paroxysmal or persistent AF undergoing first-time PVI were evaluated for (a) the frequency of AES/day on Holter recordings without AF prior to PVI, (b) AF episodes during the 90 days blanking period, and (c) AF recurrences afterward. The correlation between AES/day and both development and timing of AF recurrences was tested.

RESULTS

Preprocedural AES/day was similar in patients with paroxysmal (66 [20-295] AES/day) and persistent AF (115 [12-248] AES/day, P = .915). During the blanking period, 302 (44.2%) patients showed AF episodes. AF recurred in 379 (55.4%) patients at 203 (105-400) days after PVI. AF recurred more frequently in patients with persistent (N = 104 [69.3%]) than in patients with paroxysmal AF (N = 275 [51.5%], P < .001). Frequency of AES prior to PVI was not correlated with development (P = .203) or timing (P = .478) of AF recurrences. AF recurrences occurred both more frequently (P < .001) and earlier (P < .000) in patients with AF during the blanking period.

CONCLUSION

AES/day prior to PVI is not correlated with (timing of) AF during the blanking period or AF recurrences, and is therefore not a feasible marker for AF recurrences in patients with PAF. AF during the blanking period is correlated with AF recurrence.

Recent advances in cryoballoon ablation for atrial fibrillation

Introduction: Pulmonary vein isolation (PVI), by catheter ablation, represents the current treatment for drug-resistant atrial fibrillation (AF). Nowadays cryoballoon (CB) is a recognized ablation method in patients with atrial fibrillation, mainly due to its ease of use, leading to reproducible and fast procedures. This novel single shot technology literally revolutionized the approach to AF ablation. Areas covered: The historical development of the cryoballoon, ablation techniques and new approaches beyond the ordinary PVI and complications are summarized here. Expert opinion: Although cryoballoon ablation has greatly standardized the approach to PVI a few critical points still need to be clarified scientifically in order to further uniform this procedure in cath labs worldwide. Duration and dosage of the cryoapplication is undoubtedly a topic of great interest.

Efficacy and safety of cryoballoon ablation versus radiofrequency catheter ablation in atrial fibrillation: an updated meta-analysis

Introduction

Cryoballoon ablation (CBA) and irrigated radiofrequency catheter ablation (RFCA) are the main treatments for drug-refractory symptomatic atrial fibrillation (AF).

Aim

To compare the efficacy and safety between CBA and RFCA for the treatment of AF.

Material and methods

We searched the Embase and Medline databases for clinical studies published up to December 2016. Studies that satisfied our predefined inclusion criteria were included.

Results

After searching through the literature in the two major databases, 20 studies with a total of 9,141 patients were included in our study. The CBA had a significantly shorter procedure time (weighted mean difference (WMD) –30.38 min; 95% CI: –46.43 to –14.33, p = 0.0002) and non-significantly shorter fluoroscopy time (WMD –3.18 min; 95% CI: –6.43 to 0.07, p = 0.06) compared with RFCA. There was no difference in freedom from AF between CBA and RFCA (CBA 78.55% vs. RFCA 83.13%, OR = 1.15, 95% CI: 0.95–1.39, p = 0.14). The CBA was associated with a high risk of procedure-related complications (CBA 9.02% vs. RFCA 6.56%, OR = 1.56, 95% CI: 1.05–2.31, p = 0.03), especially phrenic nerve paralysis (PNP, OR = 10.72, 95% CI: 5.59–20.55, p < 0.00001). The risk of pericardial effusions/cardiac tamponade was low in the CBA group (CBA 1.05% vs. RFCA 1.86%, OR = 0.62, 95% CI: 0.41–0.93, p = 0.02).

Conclusions

For AF, CBA was as effective as RFCA. However, CBA had a shorter procedure time and a non-significantly shorter fluoroscopy time, a significantly high risk of PNP and a low incidence of pericardial effusions/cardiac tamponade compared with RFCA.

Cryoballoon ablation for atrial fibrillation - is cryoenergy applied only to the pulmonary vein ostium?

This case report shows that cryoablation of pulmonary veins (PV) may occasionally result in deeper lesions than expected and collateral damage in spite of proper ostial positioning of cryoballoon. The use of intracardiac vascular ultrasound and repeated computed tomography enabled detailed examination of these findings.

Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields

Background

Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations.

Methods

We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies) to create linear lesions of 12–18 mm length. Hearts were stained either with tetrazolium chloride (TTC) or propidium iodide (PI) to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume.

Results

In all animals (12/12), we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C) of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters.

Conclusions

Ablation with nsPEFs is a promising alternative to radiofrequency (RF) ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation.