Very long-term results of surgical and transcatheter ablation of long-standing persistent atrial fibrillation

Lesion durability found during mandated percutaneous catheter ablation after surgical cryo-ablation for treatment of non-paroxysmal atrial fibrillation

OBJECTIVES

Current recommendations support surgical treatment of atrial fibrillation (AF) in patients indicated for cardiac surgery. These procedures are referred to as concomitant and may be carried out using radiofrequency energy or cryo-ablation. This study aimed to assess the electrophysiological findings in patients undergoing concomitant cryo-ablation.

METHODS

Patients with non-paroxysmal AF undergoing coronary artery bypass grafting and/or valve repair/replacement were included in the trial if concomitant cryo-ablation was part of the treatment plan according to current guidelines. The patients reported in this study were assigned to undergo staged percutaneous radiofrequency catheter ablation (PRFCA), i.e., hybrid treatment, as a part of the SURHYB trial protocol.

RESULTS

We analyzed 103 patients who underwent PRFCA 105 ± 35 days after surgery. Left and right pulmonary veins (PVs) were found isolated in 65 (63.1%) and 63 (61.2%) patients, respectively. The LA posterior wall isolation and mitral isthmus conduction block were found in 38 (36.9%) and 18 (20.0%) patients, respectively. Electrical reconnections (gaps) in the left PVs were more often localized superiorly than inferiorly (57.9% vs. 26.3%, P = 0.005) and anteriorly than posteriorly (65.8% vs. 31.6%, P = 0.003). Gaps in the right PVs were more equally distributed anteroposteriorly but dominated in superior segments (72.5% vs. 40.0%, P = 0.003). There was a higher number of gaps on the roof line compared to the inferior line (131 (67.2%) vs. 67 (42.2%), P < 0.001). Compared to epicardial cryo-ablation, endocardial was more effective in creating PVs and LA posterior wall isolation (P < 0.05). Cryo-ablation using nitrous oxide (N20) or argon (Ar) gas as cooling agents was similarly effective (P = NS).

CONCLUSIONS

The effectiveness of surgical cryo-ablation in achieving transmural and durable lesions in the left atrium is surprisingly low. Gaps are located predominantly in the superior and anterior portions of the PVs and on the roof line. Endocardial cryo-ablation is more effective than epicardial ablation, irrespective of the cooling agent used.

Sequential hybrid ablation vs. surgical CryoMaze alone for treatment of atrial fibrillation: results of multicentre randomized controlled trial

AIMS

Data on the hybrid atrial fibrillation (AF) treatment are lacking in patients with structural heart disease undergoing concomitant CryoMaze procedures. The aim was to assess whether the timely pre-emptive catheter ablation would achieve higher freedom from AF or atrial tachycardia (AT) and be associated with better clinical outcomes than surgical ablation alone.

METHODS AND RESULTS

The trial investigated patients with non-paroxysmal AF undergoing coronary artery bypass grafting and/or valve repair/replacement with mandatory concomitant CryoMaze procedure who were randomly assigned to undergo either radiofrequency catheter ablation [Hybrid Group (HG)] or no further treatment (Surgery Group). The primary efficacy endpoint was the first recurrence of AF/AT without class I or III antiarrhythmic drugs as assessed by implantable cardiac monitors. The primary clinical endpoint was a composite of hospitalization for arrhythmia recurrence, worsening of heart failure, cardioembolic event, or major bleeding. We analysed 113 and 116 patients in the Hybrid and Surgery Groups, respectively, with a median follow-up of 715 (IQR: 528-1072) days. The primary efficacy endpoint was significantly reduced in the HG [41.1% vs. 67.4%, hazard ratio (HR) = 0.38, 95% confidence interval (CI): 0.26-0.57, P < 0.001] as well as the primary clinical endpoint (19.9% vs. 40.1%, HR = 0.51, 95% CI: 0.29-0.86, P = 0.012). The trial groups did not differ in all-cause mortality (10.6% vs. 8.6%, HR = 1.17, 95%CI: 0.51-2.71, P = 0.71). The major complications of catheter ablation were infrequent (1.9%).

CONCLUSION

Pre-emptively performed catheter ablation after the CryoMaze procedure was safe and associated with higher freedom from AF/AT and improved clinical outcomes.

Sequential hybrid ablation versus surgical CryoMaze alone for treatment of atrial fibrillation (SurHyb Trial): a protocol of the multicentre randomized controlled trial

BACKGROUND

Atrial fibrillation is common in patients with structural heart disease who are undergoing cardiac surgery. Surgical CryoMaze has been shown to be an effective treatment in several trials, but success rates have varied considerably, between 47-95%. The sequential hybrid approach, combining surgical CryoMaze followed by radiofrequency catheter ablation, can achieve high freedom from atrial arrhythmias. However, in patients with concomitant surgical atrial fibrillation treatment, data comparing the hybrid approach to CryoMaze alone are lacking.

METHODS

The SurHyb study was designed as a prospective, open-label, multicentre randomized trial. Patients with non-paroxysmal atrial fibrillation who were scheduled for coronary artery bypass grafting or valve repair/replacement were randomized to either surgical CryoMaze alone or surgical CryoMaze followed by radiofrequency catheter ablation 3 months post-surgery. The primary outcome measure was arrhythmia-free survival without class I or III antiarrhythmic drugs, which has been evaluated using implantable cardiac monitors.

CONCLUSIONS

This is the first randomized study that compares concomitant surgical CryoMaze alone with the staged hybrid surgical CryoMaze followed by catheter ablation, in patients with non-paroxysmal atrial fibrillation using rigorous rhythm monitoring. The results may contribute to the optimization of the treatment in patients undergoing concomitant CryoMaze for atrial fibrillation.

Atrial fibrillation fundamentals: from physiopathology to transcatheter ablation

Atrial fibrillation (AF) is a common and harmful arrhythmia. Its complex pathogenesis can be outlined using Coumel's Triangle, that considers at the base of AF three different factors: substrate, trigger, and catalyst factor. The triangle can serve as a guide to understand the mechanism of action of the different possible treatments. Anti-arrhythmic drug therapies have a modest efficacy and no proven benefit on prognosis. Interventional therapy is more effective, especially if employed in the first stages of the disease, and can reduce mortality in selected populations. Ablative schemes must be different depending on the type of AF (paroxysmal, persistent) and the presence or absence of atrial dilation.

The long-term outcomes and durability of the Cox-Maze IV procedure for atrial fibrillation

OBJECTIVE

Surgical ablation of atrial fibrillation (AF) is indicated both in patients with AF undergoing concomitant cardiac surgery and in those who have not responded to medical and/or catheter-based ablation therapy. This study examined our long-term outcomes following the Cox-Maze IV procedure (CMP-IV).

METHODS

Between May 2003 and March 2018, 853 patients underwent either biatrial CMP-IV (n = 765) or a left-sided CMP-IV (n = 88) lesion set with complete isolation of the posterior left atrium. Freedom from atrial tachyarrhythmia (ATA) was assessed for up to 10 years. Rhythm outcomes were compared in multiple subgroups. Predictors of recurrence were determined using Fine-Gray regression, allowing for death as the competing risk.

RESULTS

The majority of patients (513/853, 60%) had nonparoxysmal AF. Twenty-four percent of patients (201/853) had not responded to at least 1 catheter-based ablation. Prolonged monitoring was used in 76% (647/853) of patients during their follow-up. Freedom from ATA was 92% (552/598), 84% (213/253), and 77% (67/87) at 1, 5, and 10 years, respectively. By competing risk analysis, incidence of first ATA recurrence was 11%, 23%, and 35% at 1, 5, and 10 years, respectively. On Fine-Gray regression, age, peripheral vascular disease, nonparoxysmal AF, left atrial size, early postoperative ATAs, and absence of sinus rhythm at discharge were the predictors of first ATA recurrence over 10 years of follow-up.

CONCLUSIONS

The CMP-IV had an excellent long-term efficacy at maintaining sinus rhythm. At late follow-up, the results of the CMP-IV remained superior to those reported for catheter ablation and other forms of surgical ablation for AF. Age, left atrial size, and nonparoxysmal AF were the most relevant predictors of late recurrence.

Very long term outcome after linear versus electrogram guided ablation for persistent atrial fibrillation

The optimal ablation strategy for persistent atrial fibrillation (PsAF) remains to be defined. We sought to compare very long-term outcomes between linear ablation and electrogram (EGM)-guided ablation for PsAF. In a retrospective analysis, long-term arrhythmia-free survival compared between two propensity-score matched cohorts, one with pulmonary vein isolation (PVI) and linear ablation including roof/mitral isthmus line (LINE-group, n = 52) and one with PVI and EGM-guided ablation (EGM-group; n = 52). Overall, 99% of patients underwent successful PVI. Complete block following linear ablation was achieved for 94% of roof lines and 81% of mitral lines (both lines blocked in 75%). AF termination by EGM-guided ablation was accomplished in 40% of patients. Non-PV foci were targeted in 7 (13%) in the LINE-group and 5 (10%) patients in the EGM-group (p = 0.76). During 100 ± 28 months of follow-up, linear ablation was associated with superior arrhythmia-free survival after the initial and last procedure (1.8 ± 0.9 procedures) compared with EGM-group (Logrank test: p = 0.0001 and p = 0.045, respectively). In multivariable analysis, longer AF duration and EGM-guided ablation remained as independent predictors of atrial arrhythmia recurrence. Linear ablation might be a more effective complementary technique to PVI than EGM-guided ablation for PsAF ablation.

Hybrid ablation for atrial fibrillation: A systematic review and meta-analysis

Background

Both catheter and surgical ablation strategies offer effective treatments of atrial fibrillation (AF). The hybrid (joint surgical and catheter) ablation for AF is an emerging rhythm control strategy. We sought to determine the efficacy and safety of hybrid ablation of AF.

Methods

Systematic review and meta-analysis interrogating PubMed, EMBASE, and Cochrane databases from January 1, 1991, to November 30, 2017, using the following search terms: “Cox-maze,” “mini-maze,” “ablation methods (including radiofrequency, cryoablation, cryomaze),” and “surgery.” Included studies required ablation procedures to be hybrid and report rhythm follow-up.

Results

We included 925 patients with AF (38% persistent, 51% longstanding persistent) from 22 single-center studies (mean follow-up of 19 months). The surgical lesion set consisted of pulmonary vein isolation (n = 11) or box lesion (n = 11) with variable additional linear ablation. This was followed by sequential (n = 9), staged (n = 9), or combination (n = 4) catheter-based ablation to ensure isolation of pulmonary veins and to facilitate additional ablation or consolidation of surgically ablated lines. Overall, sinus rhythm maintenance was 79.4% (95% confidence interval [CI], 72.4-85.7] and 70.7% (95% CI, 62.2-78.7) with and without antiarrhythmic drugs, respectively at 19 ± 25 (range, 6-128) months. The use of the bipolar AtriCure Synergy system and left atrial appendage exclusion conferred superior rhythm outcome without antiarrhythmic drugs (P ≤ .01). The overall complication rate was 6.5% (95% CI, 3.4-10.2): mortality 0.2% (95% CI, 0-0.9); stroke 0.3% (95% CI, 0-1.1); reoperation for bleeding 1.6% (95% CI, 0.6-3.0); permanent pacing ~0% (95% CI, 0-0.5); conversion to sternotomy 0.3% (95% CI, 0-1.1); atrioesophageal fistula ~0% (95% CI, 0-0.5); and phrenic nerve injury 0.3% (95% CI, 0-1.1).

Conclusions

Hybrid ablation therapy for AF demonstrates favorable rhythm outcome with acceptable complication rates.

New Biparietal Bipolar Catheter Prototype for Hybrid Atrial Fibrillation Ablation

Objective

To evaluate the size and depth of linear lesions by in vitro testing with a custom-made radio frequency biparietal bipolar ablation catheter in a single-stage setting.

Methods

A custom-made catheter was created to generate linear lesions around the left atrium and pulmonary veins of an ex vivo pig. Two frames were made, 1 epicardial and 1 endocardial. A continuous copper braid electrode and an alignment system consisting of 2 parallel rows of neodymium magnets were embedded in a flexible plastic support. After 24 hours of formalin conservation, samples of the left atrium of a freshly slaughtered pig were sliced in a cryotome, thus obtaining a sequence of 100-µm thick layers extending from the endocardial to the epicardial side. After being digitized through a scanner, these layers were evaluated using morphometric computer software. For each slice, we evaluated the maximum length of the lesions, the maximum epicardial length, the maximum endocardial length, the total area of the lesion, and the total volume.

Results

Forty transmural lesions from 40 specimens were obtained. The results were the following (the number in parenthesis is the interquartile range in mm): lesion maximum length (L_MAX) was 7.297 mm (0.006), epicardial maximum length (L_EPI) was 7.291 mm (0.014), and endocardial maximum length was 7.291 mm (0.018). The total area and total volume were 1018.50 ± 36.51 mm² and 101.85 ± 3.65 mm³, respectively.

Conclusions

Our prototype showed very promising results. The next step will be to enhance the design for clinical application.

One-Stage Versus Sequential Hybrid Radiofrequency Ablation: An In Vitro Evaluation

Objective

To compare lesion size and depth between a 1-step, a sequential, and a delayed radio-frequency ablation in a hybrid setup.

Methods

Left atrium tissues obtained from fresh porcine hearts were mounted into the ABLABOX simulator. Based on the time differences between the index epicardial (epi) and consequent endocardial (endo) ablation, 3 study groups were compared: a 1-stage (SEQ- 0) group (0-minute delay), an SEQ 1 group (60-minute delay), and an SEQ 2 group (240-minute delay). During the experiment, a constant epicardial (300 gr) and endocardial (30 gr) force were applied. Per group, 20 samples were studied, and the resulting lesion size and depth were quantified with morphometric evaluation.

Results

Overall, no transmural lesion was obtained. Lesions in SEQ 0 had better maximum and minimum diameters ( P < 0.001), a larger total area ( P < 0.001), and volume ( P < 0.001) than SEQ 1 and SEQ 2. There was no statistical difference in morphometric parameters (all, P > 0.05) between the delayed procedures (SEQ 1 and SEQ 2).

Conclusions

In our in vitro model, different time sequences of combined epi–endo ablation did not result in transmural lesions. However, simultaneous epi–endo ablation produced broader and deeper lesions. Our findings need to be confirmed by further research.

Left Atrial Function after Atrial Fibrillation Cryoablation Concomitant to Minimally Invasive Mitral Valve Repair: A Pilot Study on Long-Term Results and Clinical Implications

Background and Objectives: Surgical atrial fibrillation (AF) ablation concomitant to minimally invasive mitral valve repair has been proven to offer improved short- and long-term sinus rhythm (SR) maintenance compared to mitral valve surgery only. The objective of the present study was to explore, by thorough echocardiographic assessment, long-term morphological and functional left atrial (LA) outcomes after this combined surgical procedure. Materials and Methods: From October 2006 to November 2015, 48 patients underwent minimally invasive mitral valve repair and concomitant surgical AF cryoablation. Results: After 3.8 ± 2.2 years, 30 (71.4%) of those completing the follow-up (n = 42, 87.5%) presented SR. During follow-up, four (9.5%) patients suffered from cerebrovascular accidents and two of these subjects had a long-standing persistent AF relapse and were in AF at the time of the event, while the other two were in SR. An echocardiographic study focused on LA characteristics was performed in 29 patients (69.0%). Atrial morphology and function (e.g., maximal LA volume indexed to body surface area and total LA emptying fraction derived from volumes) in patients with stable SR (60.6 ± 13.1 mL/mq and 25.1 ± 7.3%) were significantly better than in those with AF relapses (76.8 ± 16.2 mL/mq and 17.5 ± 7.4%; respectively, p = 0.008 and p = 0.015). At follow-up, patients who suffered from ischemic cerebral events had maximal LA volume indexed to body surface area 61 ± 17.8 mL/mq, with total LA emptying fraction derived from volumes 23.6 ± 13.7%; patients with strokes in SR showed very enlarged LA volume (>70 mL/mq). Conclusions: AF cryoablation concomitant with minimally invasive mitral valve repair provides a high rate of SR maintenance and this relates to improved long-term morphological and functional LA outcomes. Further prospective studies are needed to define the cut-off values determining an increase in the risk for thromboembolic complications in patients with restored stable SR.

Results of Cryoablation for Atrial Fibrillation Concomitant With Video-Assisted Minimally Invasive Mitral Valve Surgery

Interest in minimally invasive video-assisted mitral valve surgery (MIMVS) is rapidly growing. Data on concomitant atrial fibrillation (AF) ablation to MIMVS are still lacking. The present study investigates the long-term results of AF cryoablation concomitant to MIMVS. From October 2006-September 2014, 68 patients with mitral valve disease (age 65.9 ± 11.1 years, 34 men out of 68 patients, Euroscore log 5.4 ± 4.5) and drug-resistant AF underwent MIMVS via right minithoracotomy and concomitant left-sided AF endocardial cryoablation (Cryoflex Medtronic, Minneapolis, MN). Patients were independently followed up by cardiological outpatient visits and underwent electrophysiological study when indicated. In total, 44 out of 68 patients (64.7%) underwent mitral valve repair and 8 patients (11.8%) also received concomitant tricuspid valve surgery. One procedure was electively converted to full sternotomy (1.5%). Total clamp time was 97.6 ± 22.8 minutes. In March 2015, 60 patients were alive and completed the follow-up after a mean of 3.4 ± 2.0 years following the procedure. In all, 48 patients (80%) presented sinus rhythm throughout the whole follow-up. Freedom from AF was respectively 95%, 87%, and 72% at 1, 3, and 5 years, respectively. We recorded 2 pacemaker implants (3.3%). A total of 3 patients suffered symptomatic recurrences (2 atypical atrial flutter and 1 atrial fibrillation) and underwent transcatheter ablation-all the 3 patients remained in stable sinus rhythm for the remaining follow-up. In conclusions, given the favorable long-term sinus rhythm maintenance rates of concomitant cryoablation, MIMVS can also be offered to patients with symptomatic AF. AF transcatheter ablation may easily avoid further symptomatic recurrences.

Hybrid ablation for atrial fibrillation: a systematic review

PURPOSE

Hybrid ablation for AF is performed in a growing number of centers. Due to absence of guidelines, operative approaches and perioperative care differ per center. In this review, an overview of findings from published studies on hybrid ablations is given, and related topics are discussed (e.g., one- and two-stage approaches, lesion sets, and patient management).

METHODS

A systematic literature search was performed in the PubMed and Embase databases. All identified articles were screened and checked for eligibility by the two authors.

RESULTS

Twelve studies describing a total of 563 patients were selected. Due to substantial differences in approaches (one-stage, two-stage, sequential), surgical techniques (bilateral or monolateral thoracoscopy, subxiphoideal, transabdominal), energy sources (unipolar, bipolar), lesion sets (applying left or right atrial lesions), periprocedural care and endpoints (monitoring, definition of recurrence), and success rates (sinus rhythm after a mean of 26 months) are difficult to compare and varied from 27 % (without antiarrhythmic drugs, AADs) to 94 % (with AADs). For studies using bipolar devices, success rates with the use of antiarrhythmic drugs were at least 71 %. Major complications such as bleeding, sternotomy, and death occurred in 7 % of the total population (of which ten complications, 16 %, occurred in the concomitant cardiac surgery hybrid group).

CONCLUSION

The field of AF ablation has dramatically changed over the past years, with one of the most recent developments the hybrid AF ablation. Lack of matching data hinders drawing conclusions and creating guidelines. Early results however are encouraging. More data are awaiting and needed.

Surgical perspectives in the management of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia and a huge public health burden associated with significant morbidity and mortality. For decades an increasing number of patients have undergone surgical treatment of AF, mainly during concomitant cardiac surgery. This has sparked a drive for conducting further studies and researching this field. With the cornerstone Cox-Maze III “cut and sew” procedure being technically challenging, the focus in current literature has turned towards less invasive techniques. The introduction of ablative devices has revolutionised the surgical management of AF, moving away from the traditional surgical lesions. The hybrid procedure, a combination of catheter and surgical ablation is another promising new technique aiming to improve outcomes. Despite the increasing number of studies looking at various aspects of the surgical management of AF, the literature would benefit from more uniformly conducted randomised control trials.

Atrial fibrillation therapy now and in the future: drugs, biologicals, and ablation

Atrial fibrillation (AF) is a complex disease with multiple inter-relating causes culminating in rapid, seemingly disorganized atrial activation. Therapy targeting AF is rapidly changing and improving. The purpose of this review is to summarize current state-of-the-art diagnostic and therapeutic modalities for treatment of AF. The review focuses on reviewing treatment as it relates to the pathophysiological basis of disease and reviews preclinical and clinical evidence for potential new diagnostic and therapeutic modalities, including imaging, biomarkers, pharmacological therapy, and ablative strategies for AF. Current ablation and drug therapy approaches to treating AF are largely based on treating the arrhythmia once the substrate occurs and is more effective in paroxysmal AF rather than persistent or permanent AF. However, there is much research aimed at prevention strategies, targeting AF substrate, so-called upstream therapy. Improved diagnostics, using imaging, genetics, and biomarkers, are needed to better identify subtypes of AF based on underlying substrate/mechanism to allow more directed therapeutic approaches. In addition, novel antiarrhythmics with more atrial specific effects may reduce limiting proarrhythmic side effects. Advances in ablation therapy are aimed at improving technology to reduce procedure time and in mechanism-targeted approaches.

Circumflex coronary artery to left atrium fistula caused by mitral isthmus ablation

Mitral isthmus ablation is an important component of catheter ablation for persistent atrial fibrillation and mitral isthmus dependent flutters. We describe a case where mitral isthmus ablation caused a fistula between the left circumflex artery and the left atrium and symptomatic ischaemia. The fistula was successfully closed with a covered stent.