Left Atrium Volume Reduction Procedure Concomitant With Cox-Maze Ablation in Patients Undergoing Mitral Valve Surgery: A Meta-Analysis of Clinical and Rhythm Outcomes

BACKGROUND

The management of an enlarged left atrium (LA) in mitral valve (MV) disease with atrial fibrillation (AF) is still being debated. It has been postulated that a reduction in LA size may improve patient outcomes. This meta-analysis aimed to assess rhythm and clinical outcomes of combined surgical AF treatment with or without LA volume reduction (LAVR) in patients undergoing MV surgery.

METHODS

A systematic review was performed and all available literature to May 2022 was included. The primary endpoint was analysis of early and late mortality and rhythm outcomes. Secondary outcomes included early and late cerebrovascular accident (CVA) and permanent pacemaker implantation.

RESULTS

The search strategy yielded 2,808 potentially relevant articles, and 19 papers were eventually included. The pooled estimated rate of 30-day mortality was 3.76% (95% CI 2.52-5.56). The incidence rate of late mortality and late cardiac-related mortality was 1.75%/year (95% CI 0.63-4.84) and 1.04%/year (95% CI 0.31-3.53), respectively. At subgroup analysis when comparing the surgical procedure with and without AF ablation, the ablation subgroup showed a significantly lower rate of postoperative CVA (p<0.0001) and higher restoration to sinus rhythm at discharge (p=0.0124), with only a trend of lower AF recurrence at 1 year (p=0.0608). At univariable meta-regression, reintervention was significantly associated with higher late mortality (p=0.0033).

CONCLUSION

In enlarged LA undergoing MV surgery, LAVR combined with AF ablation showed a trend of improved rhythm outcomes when compared with AF ablation without LAVR. Each LAVR technique has its advantages and disadvantages, which must be managed accordingly.

A new procedure for elimination of atrial fibrillation associated with mitral valve disease: a proof-of-concept study

BACKGROUND

Left atrial enlargement and fibrosis have been linked to the pathogenesis of atrial fibrillation (AF). The authors aimed to introduce a novel concept and develop a new procedure for AF treatment based on these characteristics.

METHODS

The study included three stages. The first stage was a descriptive study to clarify the characteristics of the left atrial enlargement and fibrosis' distribution in patients with mitral valve disease and long-standing persistent AF. Based on these characteristics, the authors introduced a novel concept for AF treatment, and then translated it into a new procedure. The second stage was a proof-of-concept study with this new procedure. The third stage was a comparative effectiveness research to compare the clinical outcomes between patients with this new procedure and those who received Cox-Maze IV treatment.

RESULTS

Based on the nonuniform fashion of left atrial enlargement and fibrosis' distribution, the authors introduced a novel concept: reconstructing a left atrium with appropriate geometry and uniform fibrosis' distribution for proper cardiac conduction, and translated it into a new procedure: left atrial geometric volume reduction combined with left appendage base closure. As compared to the Cox-Maze IV procedure, the new procedure spent significantly shorter total surgery time, cardiopulmonary bypass time, and aortic cross-clamp time ( P <0.001). Besides, the new procedure was related to a shorter ICU stay period (odd ratio (OR)=0.45, 95% CI=0.26-0.78), lower costs (OR=0.15, 95% CI=0.08-0.29), and a higher rate of A wave of transmitral and transtricuspid flow reappearance (OR=1.76, 95% CI=1.02-3.04).

CONCLUSIONS

The new procedure is safe and effective for eliminating AF associated with mitral valve disease.

The Impact of Left Atrial Reduction During Surgical Ablation of Atrial Fibrillation

Enlarged left atrium (LA) is a risk factor for ablation failure after atrial fibrillation (AF) surgery. It predisposes patients to thromboembolic events, even in successful ablation; therefore, concomitant resection of the LA wall during surgical ablation was introduced. This study examined the clinical impacts of LA reduction in patients undergoing concomitant ablation for AF. This study enrolled 1484 patients with enlarged LA (≥50 mm) who underwent surgical AF ablation during major cardiac surgery between January 2001 and August 2018. Among them, 876 (59%) patients underwent concomitant LA reduction (Reduction group), whereas in the remaining 608 (41%), the LA wall was unresected (Preservation group). The primary outcome of interest was overall stroke. The secondary outcomes were overall mortality, late recurrence of AF, early postoperative complications and postoperative echocardiographic parameters. Outcomes were compared after adjusting baseline characteristics with inverse probability of treatment weighting (IPTW) using propensity score. The median follow-up was 60.1 months. After IPTW adjustment, long-term mortality (P = 0.250) and AF-free rates (P = 0.196) did not significantly differ between groups. However, the Reduction group showed a decreased risk of stroke (hazard ratio 0.54; 95% confidence interval 0.32-0.90; P = 0.018). Early postoperative complications rate such as mortality or reoperation for bleeding, was not significantly different between the 2 groups. The Reduction group showed smaller LA diameter (50.6 ± 8.0 mm vs 53.6 ± 8.9 mm; P < 0.001) on follow-up echocardiography. LA reduction effectively decreased LA size and appeared to decrease the stroke risk in patients with enlarged LA undergoing ablation for AF.

Surgical Atrial Fibrillation Ablation With and Without Left Atrium Reduction for Patients Scheduled for Mitral Valve Surgery: A Prospective Randomised Study

BACKGROUND

The influence of left atrium (LA) enlargement on atrial arrhythmia recurrence (AAR) after surgical ablation in patients with mitral valve (MV) disease remains unresolved.

OBJECTIVE

Left atrial size is critical to the success of concomitant atrial fibrillation (AF) ablation in patients scheduled for MV surgery. However, a large LA should not be a limiting factor when evaluating surgical candidates with AF if they receive appropriate treatment during concomitant ablation. This randomised study assessed whether adding LA reduction (LAR) to the maze procedure for MV surgery patients can improve freedom from AAR.

METHODS

From September 2014 to September 2017, 140 patients were randomly assigned into two groups. The maze group underwent MV surgery with concomitant surgical AF ablation (n=70). The maze + LA reduction group underwent MV surgery with concomitant AF ablation and LA reduction procedure (n=70). Rhythm outcomes were estimated by Holter monitoring, according to Heart Rhythm Society guidelines.

RESULTS

The concomitant LA reduction procedure did not increase early mortality and complications rates. Significant differences in freedom from AAR were observed at 24 months (maze, 78.4%; maze + LAR group, 92.3%; p=0.025). A significant difference in LA volume was detected at discharge (p<0.0001); however, it was not significantly different at 24 months (p=0.182).

CONCLUSIONS

Adding LA reduction to the maze procedure led to improvements in freedom from AAR for patients with AF and LA enlargement scheduled for MV surgery. A concomitant LA reduction procedure did not increase mortality and perioperative risk.

Atrial remodelling and function: implications for atrial fibrillation surgery

The exact mechanism of atrial fibrillation (AF) is still incompletely understood. A number of alterations that impact focal electrical discharge, the atrial substrate and modulating factors contribute to its pathogenesis. Atrial remodelling (resulting in atrial cardiomyopathy) sets the stage for AF development. Once present, AF results in the loss of synchronized atrial contraction, which affects ventricular filling and atrial reservoir and conduit functions. Passive atrial function is particularly important in patients with left ventricular diastolic dysfunction. AF can cause tachycardiomyopathy, a mostly reversible cardiac alteration induced by tachycardia. At a structural level, atrial support is also instrumental to the function of atrioventricular valves. All of these functions can be recovered to variable degrees via rhythm control strategies. Surgical and hybrid ablation show very promising results, especially in patients with a more advanced disease substrate. This review highlights the pathophysiological aspects of AF related to left atrial function and their practical implications for surgical rhythm management.

The Need for Consistent Predictors of Success for Surgical Ablation of Atrial Fibrillation

Objective

As with any medical therapy, identification of consistent and reliable outcome predictors is essential to understanding the efficacy of surgical ablation for atrial fibrillation. We originally intended to conduct a meta-analysis on atrial fibrillation surgical ablation to identify clinical factors that are most often associated with success. However, these studies are greatly heterogeneous. We conducted a systematic review to identify trends in outcome predictors and to provide recommendations for more uniform data analysis and reporting.

Methods

Relevant studies published between January 2005 and September 2013 were identified. To minimize heterogeneity, data were extracted only from multivariate analyses of outcome predictors. The initial approach for meta-analytic analyses was abandoned for a systematic review approach.

Results

From 604 initial citations, 19 studies with 5200 patients were included in the review. Systematic review of multivariable atrial fibrillation recurrence rates after surgical ablation revealed that studies were statistically heterogeneous, but atrial fibrillation recurrence after surgical ablation in mid-term follow-up was most often predicted by left atrium size, duration of atrial fibrillation, fine-wave atrial fibrillation, age of patient, and atrial fibrillation type.

Conclusions

The innate heterogeneity of published data precludes a meta-analysis for predictors of surgical ablation success. Of the few published studies that allow comparison, the most consistent predictors of failure were enlarged left atrium and long atrial fibrillation duration. These results underscore the need for consistent and reliable outcome predictors. We strongly recommend the development of a standardized system of measurement for consistent clinical parameters that can be used in outcome analyses for surgical ablation of atrial fibrillation.

Concomitant surgical ablation for atrial fibrillation (AF) in patients with significant atrial dilation >55 mm. Worth the effort?

Background

Concomitant Surgical AF ablation is an established procedure, recommended in guidelines. However many surgeons are reluctant to perform AF ablation in patients with significantly enlarged left atrium. We therefore analyzed outcomes of patients with left-atrial diameter >55 mm undergoing concomitant AF ablation.

Methods

Between 05/2003 and 12/2012 124 patients with significantly enlarged left-atrium >55 mm underwent concomitant surgical AF ablation. Rhythm monitoring was accomplished by implantable loop recorder (ILR) interrogation (n = 54), or 24-h Holter-ECG (n = 70). Successful ablation was defined as AF Burden <0.5 % in ILR interrogation or absence of AF episode >30 s in 24-h Holter-ECG. Primary endpoint of the study was freedom from AF at 12 months follow-up.

Results

Mean patient’s age was 65.7+/−9.6 years, 69.4 % were male. No major ablation or ILR related complications occurred. Mean LA diameter was 60.7+/−4.4 mm. Survival rate at one-year follow up was 94.4 %. 11 (8.8 %) patients received additional catheter-based ablation, while 23 (18.5 %) had an electrical cardioversion during follow-up period. Overall freedom from AF rate after one-year follow-up was 64.4 % and 59.4 % off antiarrhythmic drugs respectively. Logistic regression analysis identified preoperative paroxysmal AF, duration of AF and LA diameter > 70 mm as predictors for rhythm outcome at 12 months follow-up.

Conclusion

In this patient cohort with significantly enlarged LA diameter, concomitant surgical AF ablation provided freedom from AF of 64.4 % after one-year follow-up. However in this patient population, an accurate postoperative care with interventions like medical or- electrical cardioversion and additional catheter based ablation is necessary to achieve satisfactory results.

The CURE-AF trial: a prospective, multicenter trial of irrigated radiofrequency ablation for the treatment of persistent atrial fibrillation during concomitant cardiac surgery

BACKGROUND

Ablation technology has been introduced to replace the surgical incisions of the Cox-Maze procedure in order to simplify the operation. However, the efficacy of these ablation devices has not been prospectively evaluated.

OBJECTIVE

The purpose of this study was to examine the efficacy and safety of irrigated unipolar and bipolar radiofrequency ablation for the treatment of persistent and long-standing persistent atrial fibrillation (AF) during concomitant cardiac surgical procedures.

METHODS

Between May 2007 and July 2011, 150 consecutive patients were enrolled at 15 U.S. centers. Patients were followed for 6 to 9 months, at which time a 24-hour Holter recording and echocardiogram were obtained. Recurrent AF was defined as any atrial tachyarrhythmia (ATA) lasting over 30 seconds on the Holter monitor. The safety end-point was the percent of patients who suffered a major adverse event within 30 days of surgery. All patients underwent a biatrial Cox-Maze lesion set.

RESULTS

Operative mortality was 4%, and there were 4 (3%) 30-day major adverse events. Overall freedom from ATAs was 66%, with 53% of patients free from ATAs and also off antiarrhythmic drugs at 6 to 9 months. Increased left atrial diameter, shorter total ablation time, and an increasing number of concomitant procedures were associated with recurrent AF (P <.05).

CONCLUSION

Irrigated radiofrequency ablation for treatment of AF during cardiac surgery was associated with a low complication rate. No device-related complications occurred. The Cox-Maze lesion set was effective at restoring sinus rhythm and had higher success rates in patients with smaller left atrial diameters and longer ablation times.

Guideline for the surgical treatment of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and its prevalence is ∼1-2% of the general population, but higher with increasing age and in patients with concomitant heart disease. The Cox-maze III procedure was a groundbreaking development and remains the surgical intervention with the highest cure rate, but due to its technical difficulty alternative techniques have been developed to create the lesions sets. The field is fast moving and there are now multiple energy sources, multiple potential lesion sets and even multiple guidelines addressing the issues surrounding the surgical treatment of AF both for patients undergoing this concomitantly with other cardiac surgical procedures and also as stand-alone procedures either via sternotomy or via videothoracoscopic techniques. The aim of this document is to bring together all major guidelines in this area into one resource for clinicians interested in surgery for AF. Where we felt that guidance was lacking, we also reviewed the evidence and provided summaries in those areas. We conclude that AF surgery is an effective intervention for patients with all types of AF undergoing concomitant cardiac surgery to reduce the incidence of AF, as demonstrated in multiple randomized studies. There is some evidence that this translates into reduced stroke risk, reduced heart failure risk and longer survival. In addition, symptomatic patients with AF may be considered for surgery after failed catheter intervention or even as an alternative to catheter intervention where either catheter ablation is contraindicated or by patient choice.