Comparing energy sources for surgical ablation of atrial fibrillation: a Bayesian network meta-analysis of randomized, controlled trials

Efficiency and safety of ablation procedure for the treatment of atrial fibrillation in valve surgery: A PRISMA-compliant cumulative systematic review and meta-analysis

BACKGROUND

Atrial fibrillation is the main complication of patients who suffer from valvular heart disease (VHD), which may lead to an increased susceptibility to ventricular tachycardia, atrial dysfunction, heart failure, and stroke. Therefore, seeking a safe and effective therapy is crucial in prolonging the lives of patients with VHD and improving their quality of life.

METHODS

Our target database included PubMed, Web of Science, Embase, and Cochrane Library, from which published articles were retrieved from inception to June 2020. We retrieved all randomized controlled trials (RCTs) that compared patients undergoing valve surgery with (VSA) or without ablation (VS) procedure. Studies to be included were screened and data extraction was performed independently by 2 investigators. The Cochrane risk-of-bias table was used to evaluate the methodological quality of the included RCTs. The mean difference (MD) with 95% confidence interval (CI) and relative risk (RR) ratio was calculated to analyze the data. Heterogeneity was evaluated using I2 and chi-square tests. Egger test and the trim and fill analysis were used to further determine publication bias.

RESULTS

Fourteen RCTs that included 1376 patients were eventually selected for this meta-analysis. Surgical ablation was found to be effective in restoring sinus rhythm in valvular surgery patients at discharge (RR 2.91, 95% CI [1.17, 7.20], I2 97%, P = .02), 3 to 6 months (RR 2.85, 95% CI [2.27, 3.58], I2 49%, P < .00001), 12 months, and more than 1 year after surgery (RR 3.54, 95% CI [2.78, 4.51], I2 27%, P < .00001). All-cause mortality (RR 0.98, 95% CI [0.64, 1.51], I2 0%, P = .94) and stroke (RR 1.29, 95% CI [0.70, 2.39], I2 0%, P = .57) were similar in the VSA and VS groups. Compared with VS, VSA prolonged cardiopulmonary bypass time (MD 30.44, 95% CI [17.55, 43.33], I2 88%, P < .00001) and aortic cross-clamping time (MD 19.57, 95% CI [11.10, 28.03], I2 89%, P < .00001). No significant differences were found between groups with respect to the risk of bleeding (RR 0.64, 95% CI [0.37, 1.12], I2 0%, P = .12), heart failure (RR 1.11, 95% CI [0.63, 1.93], I2 0%, P = .72), and low cardiac output syndrome (RR 1.41, 95% CI [0.57, 3.46], I2 18%, P = .46). However, the demand for implantation of a permanent pacemaker was significantly higher in the VSA group (RR 1.84, 95% CI [1.15, 2.95], I2 0%, P = .01).

CONCLUSION

Although we found high heterogeneity in the restoration of sinus rhythm at discharge, we assume that the comparison is valid at this time, given the current state in the operating room. This study provides evidence of the efficacy and security of concomitant ablation intervention for patients with VHD and atrial fibrillation. Surgical ablation would increase the safety of implantation of a permanent pacemaker in the population that underwent valve surgery.

Safety and efficacy of concomitant ablation for atrial fibrillation in rheumatic mitral valve surgery: A meta-analysis

OBJECTIVES

This review aimed to evaluate the safety and efficacy of concomitant surgical ablation (SA) for patients with atrial fibrillation (AF) undergoing rheumatic mitral valve (MV) surgery.

METHODS

A systematic search of relevant studies focusing on SA for patients with AF undergoing rheumatic MV surgery was performed. The primary outcomes included mortality, efficacy, and complications.

RESULTS

Four randomized controlled trials (RCTs) and four observational studies covering 1931 patients met the inclusion criteria. In RCTs, no significant differences in reoperation for bleeding, low cardiac output syndrome, thromboembolic events, and early (risk ratio [RR], 2.07; 95% confidence intervals [CI], 0.37-11.40; p = .41) and midterm all-cause death (RR, 1.07; 95% CI, 0.40-2.88; p = .89) were noted between the SA group and the nonablation group. These results were similar to those obtained from observational studies. However, ablation was associated with a higher incidence of permanent pacemaker implantation (RR, 2.44; 95% CI, 1.15-5.18; p = .02) in observational studies but not in RCTs (RR, 2.03; 95% CI, 0.19-21.26; p = .56). Furthermore, additional SA was significantly more effective in sinus rhythm (SR) restoration than MV surgery alone at discharge and at the 12-month and 3-year follow-ups.

CONCLUSIONS

Concomitant SA during rheumatic MV surgery does not increase perioperative adverse events. In addition, SA promotes considerable restoration of SR. Although some evidence exists that permanent pacemaker implantation is more common after ablation, not all studies support this notion.

Surgical Ablation of Permanent Atrial Fibrillation: Age, LV Dilatation, Obesity

OBJECTIVES

 Although concomitant surgical ablation can help to reach freedom from atrial fibrillation (FREEAF) even in patients with permanent atrial fibrillation (AF), some cardiac surgeons hesitate to perform concomitant ablation to avoid perioperative risk escalation. Here, we investigated outcome and predicators of therapeutic success of concomitant surgical ablation in an all-comers study.

METHODS

 Ablation-naïve patients with formerly accepted permanent AF (FAP, n = 41) or paroxysmal AF (parAF, n = 24) underwent concomitant epicardial bipolar radio frequency ablation and implantable loop recorder (ILR) at two surgical departments. Follow-up examination for 24 months included electrocardiogram, ILR readout, 24h Holter monitoring, echocardiography, and blood sampling.

RESULTS

 Eighty-six percent of parAF and 70% of FAP patients reached FREEAF (month 24). Mortality was low (parAF/FAP: 5.3 ± 0.2%/4.1 ± 0.3%; p < 0.05; EuroScoreII; 6.1 ± 0.7%/6.4 ± 0.4%, p = ns) and no strokes occurred. FREEAF induced atrial reverse remodeling (left atrial [LA] diameter: -6.7 ± 2.2 mm) and improved cardiac function (left ventricular ejection fraction [LVEF]: +7.3 ± 2.8%), while AF resulted in further atrial dilation (+8.0 ± 1.0 mm, p < 0.05) and LVEF reduction (-7.0 ± 1.3%, p < 0.05). Higher LV (odds ratio [OR]: 1.164) and LA diameter (OR: 1.218), age (OR: 1.180) and body mass index (BMI) (OR: 1.503) increased the risk factors of AF recurrence. Patients remaining in sinus rhythm (SR) demonstrated a decrease in BMI, while AF recurrence was associated with stable overweight. Further aging did not reduce FREEAF.

CONCLUSIONS

 Long-term SR is achievable by concomitant surgical ablation even in FAP patients. Therefore, it should be offered routinely. Obesity influences therapeutic long-term success but may also offer addressable therapeutic targets to reach higher FREEAF rates.

Immunopathogenesis and biomarkers of recurrent atrial fibrillation following ablation therapy in patients with preexisting atrial fibrillation

INTRODUCTION

Recurrent atrial fibrillation (RAF) following ablation therapy occurs in about 50% of patients. The pathogenesis of RAF is unknown, but is believed to be driven by atrial remodeling in the setting of background inflammation. Structural, electrophysiological and mechanical remodeling has been associated with atrial fibrillation (AF). Inflammation and fibrotic remodeling are the major factors perpetuating AF, as mediators released from the atrial tissues and cardiomyocytes due to mechanical and surgical injury could initiate the inflammatory process. In this article, we have critically reviewed the key mediators that may serve as potential biomarkers to predict RAF. Areas covered: Damage associated molecular patterns, heat shock proteins, inflammatory cytokines, non-inflammatory markers, markers of inflammatory cell activity, and markers of collagen deposition and metabolism are evaluated as potential biomarkers with molecular treatment options in RAF. Expert commentary: Establishing biomarkers to predict RAF could be useful in reducing morbidity and mortality. Investigations into the role of DAMPs participating in a sterile immune response may provide greater insight into the pathogenesis of RAF. Markers evaluating immune cell activity, collagen deposition, and levels of heat shock proteins show the greatest promise as potential biomarkers to predict RAF and develop novel therapies.

Effectiveness and safety of simultaneous hybrid thoracoscopic endocardial catheter ablation of atrial fibrillation in obese and non-obese patients

Background

We evaluated the safety and effectiveness of the hybrid thoracoscopic endocardial epicardial ablation technique for the treatment of atrial fibrillation (AF) in obese versus non-obese patients.

Methods

Between January 2010 and January 2015, a cohort of 61 patients were retrospectively identified to undergo ablation of AF as a stand-alone procedure using a thoracoscopic, hybrid epicardial-endocardial technique. All patients underwent continuous 7-day Holter monitoring at 3, 6 months, 1 year and yearly thereafter.

Results

A total of 40% of the obese cohort had persistent or long-standing AF, compared to 54.9% of the non-obese cohort. There were no deaths or conversion to cardiopulmonary bypass required. At 3-year follow-up, 60% of the obese group were in sinus rhythm (SR) with no episode of AF, atrial flutter or atrial tachycardia lasting 30 s off anti-arrhythmic drugs. This was compared to 70.6% in the non-obese group, with no significant difference between the groups (P=0.468). For success rates on anti-arrhythmic drugs, this was 80% in the obese group compared to 86% in the non-obese group at 3-year follow-up (P=0.637). No patient died and no thromboembolic/bleeding events or procedure-related complications occurred during the follow-up.

Conclusions

In a retrospective cohort with approximately half with persistent or long-standing AF, thoracoscopic hybrid epicardial endocardial ablation proved to be equally effective and safe in obese versus non-obese patients. Current preliminary findings require further validation in multi-institutional prospective studies with larger sample sizes.

Surgical and Hybrid Ablation of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia in humans and is known to be associated with an increased risk of stroke, dementia, heart failure and mortality. Non-pharmacological therapy with ablation using either surgical or percutaneous techniques is recommended in drug refractory AF. Early attempts to devise procedures to ablate AF and restore sinus rhythm culminated with the Cox-Maze procedure, the first truly successful procedure. Since then, ablation surgery has been conducted predominately as a concomitant procedure. The Cox Maze procedure is complex and technically demanding and has, therefore, been extensively modified with new techniques for creating the linear ablation lines, new lesion sets, minimally invasive surgical techniques and most recently hybrid surgical-catheter ablation techniques. Surgical ablation techniques result in a marked reduction in atrial fibrillation when compared to conventional therapy with only a small increase in procedural risk. However, further research is required to more accurately quantify those benefits and to determine the optimal lesion sets, specific to the underlying arrhythmia mechanism and the optimal energy sources for ablation.

Current Interventional and Surgical Management of Congenital Heart Disease: Specific Focus on Valvular Disease and Cardiac Arrhythmias

Successful outcome in the care of patients with congenital heart disease depends on a comprehensive multidisciplinary team. Surgery is offered for almost every heart defect, despite complexity. Early mortality for cardiac surgery in the neonatal period is ≈10% and beyond infancy is <5%, with 90% to 95% of patients surviving with a good quality of life into the adult years. Advances in imaging have facilitated accurate diagnosis and planning of interventions and surgical procedures. Similarly, advances in the perioperative medical management of patients, particularly with intensive care, has also contributed to improving outcomes. Arrhythmias and heart failure are the most common late complications for the majority of defects, and reoperation for valvar problems is common. Lifelong surveillance for monitoring of recurrent or residual structural heart defects, as well as periodic assessment of cardiac function and arrhythmia monitoring, is essential for all patients. The field of congenital heart surgery is poised to incorporate new innovations such as bioengineered cells and scaffolds that will iteratively move toward bioengineered patches, conduits, valves, and even whole organs.

Surgical Treatment of Atrial Fibrillation in Patients with Rheumatic Valve Disease

OBJECTIVE:

To assess heart rhythm and predictive factors associated with sinus rhythm after one year in patients with rheumatic valve disease undergoing concomitant surgical treatment of atrial fibrillation. Operative mortality, survival and occurrence of stroke after one year were also evaluated.

METHODS:

Retrospective longitudinal observational study of 103 patients undergoing rheumatic mitral valve surgery and ablation of atrial fibrillation using uni- or bipolar radiofrequency between January 2013 and December 2014. Age, gender, functional class (NYHA), type of atrial fibrillation, EuroSCORE, duration of atrial fibrillation, stroke, left atrial size, left ventricular ejection fraction, cardiopulmonary bypass time, myocardial ischemia time and type of radiofrequency were investigated.

RESULTS:

After one year, 66.3% of patients were in sinus rhythm. Sinus rhythm at hospital discharge, lower left atrial size in the preoperative period and bipolar radiofrequency were associated with a greater chance of sinus rhythm after one year. Operative mortality was 7.7%. Survival rate after one year was 92.3% and occurrence of stroke was 1%.

CONCLUSION:

Atrial fibrillation ablation surgery with surgical approach of rheumatic mitral valve resulted in 63.1% patients in sinus rhythm after one year. Discharge from hospital in sinus rhythm was a predictor of maintenance of this rhythm. Increased left atrium and use of unipolar radiofrequency were associated with lower chance of sinus rhythm. Operative mortality rate of 7.7% and survival and stroke-free survival contribute to excellent care results for this approach.

Characteristics of the new AtriCure cryoFORM® cryoablation probe for the surgical treatment of cardiac arrhythmias

INTRODUCTION

Atrial fibrillation has a significant impact on patient mortality and morbidity. In particular, stroke is a frequent complication associated with atrial fibrillation. In recent years, various treatment options have been developed that are based on the elimination of atypical electrically active atrial areas. Areas covered: This manuscript presents a new cryoablation probe from AtriCure Inc. In addition to describing the characteristics of the probe, we also discuss atrial fibrillation and its surgical therapy options as well as the basics of cryosurgery. The cryoFORM® cryoablation probe is an ablation system developed for cardiothoracic surgeons that utilizes nitrous oxide (N₂O) to create continuous transmural lesions that block propagation of atrial activation. The main features of the probe are an excellent working capacity due to the use of N₂O, high flexibility, and, in combination with the cryoICE® Box V6, an active defrost mode for quick detachment. Expert commentary: The cryoFORM® ablation probe is a new device for the treatment of atrial fibrillation using N₂O as an energy source. The probe is made from stainless steel and has a corrugated surface, a design that provides a higher flexibility than the cryoICE probe.

Atrial flutter after surgical maze: incidence, diagnosis, and management

PURPOSE OF REVIEW

The prevalence of atrial fibrillation is increasing and surgical ablation is becoming more common, both as a stand-alone procedure and when performed concomitantly with other cardiac surgery. Although surgical ablation is effective, with it unique challenges arise, including iatrogenic macroreentrant tachycardias that are often highly symptomatic and difficult to manage conservatively.

RECENT FINDINGS

Postsurgical ablation, localization of the arrhythmic circuit is difficult to determine using surface ECG alone because of alterations in the atrial myocardium, and multiple different pathways are often present. Most, however, localize to the left atrium, and percutaneous catheter ablation is emerging as an effective treatment modality.

SUMMARY

Patients with complex postoperative arrhythmias should be referred to a dedicated atrial fibrillation center when possible and symptomatic arrhythmias mapped and ablated. Knowledge of the previously performed surgical lesion set is of vital importance in understanding the mechanism of the arrhythmia and increasing procedural success rates.

VIDEO ABSTRACT

http://links.lww.com/HCO/A31.

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.

Concomitant atrial fibrillation surgery for people undergoing cardiac surgery

BACKGROUND

People with atrial fibrillation (AF) often undergo cardiac surgery for other underlying reasons and are frequently offered concomitant AF surgery to reduce the frequency of short- and long-term AF and improve short- and long-term outcomes.

OBJECTIVES

To assess the effects of concomitant AF surgery among people with AF who are undergoing cardiac surgery on short-term and long-term (12 months or greater) health-related outcomes, health-related quality of life, and costs.

SEARCH METHODS

Starting from the year when the first "maze" AF surgery was reported (1987), we searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (March 2016), MEDLINE Ovid (March 2016), Embase Ovid (March 2016), Web of Science (March 2016), the Database of Abstracts of Reviews of Effects (DARE, April 2015), and Health Technology Assessment Database (HTA, March 2016). We searched trial registers in April 2016. We used no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials evaluating the effect of any concomitant AF surgery compared with no AF surgery among adults with preoperative AF, regardless of symptoms, who were undergoing cardiac surgery for another indication.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted data. We evaluated the risk of bias using the Cochrane 'Risk of bias' tool. We included outcome data on all-cause and cardiovascular-specific mortality, freedom from atrial fibrillation, flutter, or tachycardia off antiarrhythmic medications, as measured by patient electrocardiographic monitoring greater than three months after the procedure, procedural safety, 30-day rehospitalisation, need for post-discharge direct current cardioversion, health-related quality of life, and direct costs. We calculated risk ratios (RR) for dichotomous data with 95% confidence intervals (CI) using a fixed-effect model when heterogeneity was low (I² ≤ 50%) and random-effects model when heterogeneity was high (I² > 50%). We evaluated the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework to create a 'Summary of findings' table.

MAIN RESULTS

We found 34 reports of 22 trials (1899 participants) with five additional ongoing studies and three studies awaiting classification. All included studies were assessed as having high risk of bias across at least one domain. The effect of concomitant AF surgery on all-cause mortality was uncertain when compared with no concomitant AF surgery (7.0% versus 6.6%, RR 1.14, 95% CI 0.81 to 1.59, I² = 0%, 20 trials, 1829 participants, low-quality evidence), but the intervention increased freedom from atrial fibrillation, atrial flutter, or atrial tachycardia off antiarrhythmic medications > three months (51.0% versus 24.1%, RR 2.04, 95% CI 1.63 to 2.55, I² = 0%, eight trials, 649 participants, moderate-quality evidence). The effect of concomitant AF surgery on 30-day mortality was uncertain (2.3% versus 3.1%, RR 1.25 95% CI 0.71 to 2.20, I² = 0%, 18 trials, 1566 participants, low-quality evidence), but the intervention increased the risk of permanent pacemaker implantation (6.0% versus 4.1%, RR 1.69, 95% CI 1.12 to 2.54, I² = 0%, 18 trials, 1726 participants, moderate-quality evidence). Investigator-defined adverse events, including but limited to, need for surgical re-exploration or mediastinitis, were not routinely reported but were not different between the two groups (other adverse events: 24.8% versus 23.6%, RR 1.07, 95% CI 0.85 to 1.34, I² = 45%, nine trials, 858 participants), but the quality of this evidence was very low.

AUTHORS' CONCLUSIONS

For patients with AF undergoing cardiac surgery, there is moderate-quality evidence that concomitant AF surgery approximately doubles the risk of freedom from atrial fibrillation, atrial flutter, or atrial tachycardia off anti-arrhythmic drugs while increasing the risk of permanent pacemaker implantation. The effects on mortality are uncertain. Future, high-quality and adequately powered trials will likely affect the confidence on the effect estimates of AF surgery on clinical outcomes.

Epicardial thoracoscopic ablation versus endocardial catheter ablation for management of atrial fibrillation: a systematic review and meta-analysis

OBJECTIVES

In the treatment of patients with atrial fibrillation (AF), the efficacy and safety of epicardial thoracoscopic ablation (TA) versus endocardial catheter ablation (CA) using radiofrequency energy remains unclear. This meta-analysis was performed to assess the efficacy and safety of each ablation technique using a pooled comparative analysis.

METHODS

Studies comparing the efficacy and safety of TA and CA were identified by searching electronic databases. Those that reported patients' freedom from atrial arrhythmia and significant side effects were included.

RESULTS

Three randomized controlled trials (RCTs) and two retrospective cohort studies with a total of 587 patients were included in the meta-analysis (273 patients underwent TA and 314 patients underwent CA). The proportion of patients who were free of atrial arrhythmia without antiarrhythmic drugs during 12 months of follow-up was significantly higher after TA than after CA in the RCTs [P < 0.001; relative risk (RR), 1.77; 95% confidence interval (CI), 1.34-2.32] and in the retrospective cohort studies (P = 0.010; RR, 1.68; 95% CI, 1.12-2.51). The incidence of significant side effects during the post-procedural period was significantly higher in the TA group than in the CA group in both the RCT (P = 0.007; RR, 7.23; 95% CI, 1.71-30.49) and the retrospective cohort studies (P = 0.020; RR, 4.39; 95% CI, 1.33-14.46).

CONCLUSIONS

Based on the available data, TA was found to be more effective than CA in achieving freedom from atrial arrhythmia; however, TA had a higher rate of immediate post-procedural complications than CA.

Electrophysiological Perspectives on Hybrid Ablation of Atrial Fibrillation

To overcome limitations of minimally invasive surgical ablation as a standalone procedure in eliminating atrial fibrillation (AF), hybrid approaches incorporating adjunctive endovascular catheter ablation have been proposed in recent years. The endovascular component targets residual conduction gaps and identifies additional electrophysiological targets with the goal of minimizing recurrent atrial arrhythmia. We performed a systematic review of published studies of hybrid AF ablation, analyzing 432 pooled patients (19% paroxysmal, 29% persistent, 52% long-standing persistent) treated using three different approaches: A. bilateral thoracoscopy with bipolar radiofrequency (RF) clamp-based approach; B. right thoracoscopic suction monopolar RF catheter-based approach; and C. subxiphoid posterior pericardioscopic ("convergent") approach. Freedom from recurrence off antiarrhythmic medications at 12 months was seen in 88.1% [133/151] for A, 73.4% [47/64] for B, and 59.3% [80/135] for C, with no significant difference between paroxysmal (76.9%) and persistent/long-standing persistent AF (73.4%). Death and major surgical complications were reported in 8.5% with A, 0% with B and 8.6% with C. A critical appraisal of hybrid ablation is presented, drawing from experiences and insights published over the years on catheter ablation of AF, with a discussion of the rationale underlying hybrid ablation, its strengths and limitations, where it may have a unique role in clinical management of patients with AF, which questions remain unanswered and areas for further investigation.