Designing comparative effectiveness trials of surgical ablation for atrial fibrillation: experience of the Cardiothoracic Surgical Trials Network

Partial upper sternotomy for concomitant left atrial ablation and aortic valve replacement

BACKGROUND

Minimally invasive access via partial sternotomy has been established for aortic valve surgery in the past years. But concomitant procedures like atrial ablation and aortic valve replacement via partial upper sternotomy have not been investigated so far. We therefore present our operative technique and results in terms of safety and efficacy, including follow-up and quality of life.

METHODS

Between February 2007 and March 2014 a total of 67 patients undergoing isolated minimally invasive aortic valve replacement received concomitant left atrial ablation at our centre. Operative technique and short- and midterm results are described, including quality of life assessment using the SF-36 questionnaire.

RESULTS

Operative techniqual success rate was 98.5%. We observed only one (1.5%) ablation-related conversion to full sternotomy. Operative times, reexploration and stroke rates as well as 30-day mortality are comparable to open procedures. Efficacy: The proportions of patients in sinus rhythm at discharge was 54.5% for paroxysmal AF patients and 27.7% overall. After a mean follow-up time of 38.0±22.6 months the cardiac related mortality rate was 4.5%, the rate of sinus rhythm was 72.7% for paroxysmal AF patients and 36.8% overall. Of survivors, overall mean quality of life was 7.3±2.1 as measured by SF-36.

CONCLUSIONS

Concomitant left atrial ablation and aortic valve replacement can safely be performed via partial sternotomy and results are non-inferior to open surgery.

National Heart, Lung, and Blood Institute cardiovascular clinical trial perspective

The National Heart, Lung, and Blood Institute (NHLBI) has played an important role in funding the clinical science that supports many contemporary cardiology practice guidelines and in shaping the conduct of cardiovascular clinical trials. This Perspective outlines contemporary funding options as well as select important NHLBI policies, philosophy, and priorities.

Sick Sinus Syndrome After the Maze Procedure Performed Concomitantly With Mitral Valve Surgery

Background

To characterize the development of sick sinus syndrome (SSS) after the additive maze procedure (MP) during mitral valve surgery.

Methods and Results

Follow‐up data (median, 3.6 years) of 750 patients with a prevalence of rheumatic cause of 57.6% were analyzed. SSS occurred in 35 patients with a time‐dependent increase: the incidence rates at 1, 2, and 4 years after surgery were 2.9%, 3.7%, and 4.3%, respectively. The additive MP showed higher risks of SSS development (hazard ratio, 7.44; 95% confidence interval, 3.45–16.05; P<0.001) and pacemaker implantation (hazard ratio, 3.61; 95% confidence interval, 1.95–6.67; P<0.001). Patients who developed SSS showed higher 4‐year rates of clinical events (death, stroke, and hospital admission) (67.5±8.5% versus 33.0±1.9%; P<0.001). After adjustment for age and preoperative peak systolic pulmonary artery pressure, the lesion extent (biatrial versus left atrial MP), not the underlying cause (rheumatic versus nonrheumatic), was independently associated with SSS development (hazard ratio, 3.58; 95% confidence interval, 1.08–11.86; P=0.037). The adverse effect of the biatrial MP was confirmed in patients with trivial or mild preoperative tricuspid regurgitation showing higher SSS incidence (4.6±1.4% versus 1.0±0.7%; P=0.023), not in those with moderate‐to‐severe tricuspid regurgitation (6.8±1.7% versus 3.8±3.8%; P=0.337). Recurrence of atrial fibrillation was not associated with the lesion extent of the MP.

Conclusions

After the additive MP, the ongoing risk of SSS development should be acknowledged irrespective of the underlying cause. Considering additive risk of biatrial MP with similar atrial fibrillation recurrence rate, minimizing lesion extent is warranted.

Amaze: a randomized controlled trial of adjunct surgery for atrial fibrillation

OBJECTIVES

Atrial fibrillation (AF) reduces survival and quality of life (QoL). It can be treated at the time of major cardiac surgery using ablation procedures ranging from simple pulmonary vein isolation to a full maze procedure. The aim of this study is to evaluate the impact of adjunct AF surgery as currently performed on sinus rhythm (SR) restoration, survival, QoL and cost-effectiveness.

METHODS

In a multicentre, Phase III, pragmatic, double-blinded, parallel-armed randomized controlled trial, 352 cardiac surgery patients with >3 months of documented AF were randomized to surgery with or without adjunct maze or similar AF ablation between 2009 and 2014. Primary outcomes were SR restoration at 1 year and quality-adjusted life years at 2 years. Secondary outcomes included SR at 2 years, overall and stroke-free survival, medication, QoL, cost-effectiveness and safety.

RESULTS

More ablation patients were in SR at 1 year [odds ratio (OR) 2.06, 95% confidence interval (CI) 1.20-3.54; P = 0.009]. At 2 years, the OR increased to 3.24 (95% CI 1.76-5.96). Quality-adjusted life years were similar at 2 years (ablation - control -0.025, P = 0.6319). Significantly fewer ablation patients were anticoagulated from 6 months postoperatively. Stroke rates were 5.7% (ablation) and 9.1% (control) (P = 0.3083). There was no significant difference in stroke-free survival [hazard ratio (HR) = 0.99, 95% CI 0.64-1.53; P = 0.949] nor in serious adverse events, operative or overall survival, cardioversion, pacemaker implantation, New York Heart Association, EQ-5D-3L and SF-36. The mean additional ablation cost per patient was £3533 (95% CI £1321-£5746). Cost-effectiveness was not demonstrated at 2 years.

CONCLUSIONS

Adjunct AF surgery is safe and increases SR restoration and costs but not survival or QoL up to 2 years. A continued follow-up will provide information on these outcomes in the longer term.

Study registration

ISRCTN82731440 (project number 07/01/34).

Biatrial maze procedure versus pulmonary vein isolation for atrial fibrillation during mitral valve surgery: New analytical approaches and end points

OBJECTIVE

To use novel statistical methods for analyzing the effect of lesion set on (long-standing) persistent atrial fibrillation (AF) in the Cardiothoracic Surgical Trials Network trial of surgical ablation during mitral valve surgery (MVS).

METHODS

Two hundred sixty such patients were randomized to MVS + surgical ablation or MVS alone. Ablation was randomized between pulmonary vein isolation and biatrial maze. During 12 months postsurgery, 228 patients (88%) submitted 7949 transtelephonic monitoring (TTM) recordings, analyzed for AF, atrial flutter (AFL), or atrial tachycardia (AT). As previously reported, more ablation than MVS-alone patients were free of AF or AF/AFL at 6 and 12 months (63% vs 29%; P < .001) by 72-hour Holter monitoring, without evident difference between lesion sets (for which the trial was underpowered).

RESULTS

Estimated freedom from AF/AFL/AT on any transmission trended higher after biatrial maze than pulmonary vein isolation (odds ratio, 2.31; 95% confidence interval, 0.95-5.65; P = .07) 3 to 12 months postsurgery; estimated AF/AFL/AT load (ie, proportion of TTM strips recording AF/AFL/AT) was similar (odds ratio, 0.90; 95% confidence interval, 0.57-1.43; P = .6). Within 12 months, estimated prevalence of AF/AFL/AT by TTM was 58% after MVS alone, and 36% versus 23% after pulmonary vein isolation versus biatrial maze (P < .02).

CONCLUSIONS

Statistical modeling using TTM recordings after MVS in patients with (long-standing) persistent AF suggests that a biatrial maze is associated with lower AF/AFL/AT prevalence, but not a lower load, compared with pulmonary vein isolation. The discrepancy between AF/AFL/AT prevalence assessed at 2 time points by Holter monitoring versus weekly TTM suggests the need for a confirmatory trial, reassessment of definitions for failure after ablation, and validation of statistical methods for assessing atrial rhythms longitudinally.

Is It Conceivable to Still Perform the Cut and Sew Cox Maze III Procedure in the Current Era?

To determine whether cut and sew Cox maze III procedure is still associated with adequate safety endpoints when performed in conjunction with other open-heart procedures. Between January 2008 and January 2015, 113 consecutive adult patients were submitted to cut and sew Cox maze III procedure in association with other operations for structural heart disease. Mean age was 49 years and 80 (70.8%) were females. Longstanding or persistent atrial fibrillation has occurred in 87.6% and rheumatic heart disease in 80.7%. Valve surgery was performed in 98.2%. The number of associated procedures was correlated with morbidity and hospital mortality. Overall mean cardiopulmonary bypass and aortic cross-clamping times were 129 ± 26 and 105 ± 23 minutes, respectively. Hospital mortality was 1.77%, re-exploration for bleeding 0.9%, cerebrovascular accident 1.8%, and acute renal failure requiring hemodialysis 2.6%. The greater number of associated procedures did not correlate with poorer safety outcomes. Permanent pacemaker was required in 18.2% of those with three associated procedures, as opposed to 4% with two procedures and no requirement with one procedure (P = .01). Frequency of sinus rhythm was 88%, 88%, and 85% at 6, 12, and 24 months, respectively. In a contemporary single-center cohort of predominantly rheumatic patients, the surgical treatment of atrial fibrillation associated with structural heart disease by means of cut and sew Cox maze III procedure is safe, with low morbidity and mortality rates. Surgical complexity, defined by number of associated procedures, did not translate into poorer safety endpoints, except for greater need of permanent pacemaker.

Probability of atrial fibrillation after ablation: Using a parametric nonlinear temporal decomposition mixed effects model

Atrial fibrillation is an arrhythmic disorder where the electrical signals of the heart become irregular. The probability of atrial fibrillation (binary response) is often time varying in a structured fashion, as is the influence of associated risk factors. A generalized nonlinear mixed effects model is presented to estimate the time-related probability of atrial fibrillation using a temporal decomposition approach to reveal the pattern of the probability of atrial fibrillation and their determinants. This methodology generalizes to patient-specific analysis of longitudinal binary data with possibly time-varying effects of covariates and with different patient-specific random effects influencing different temporal phases. The motivation and application of this model is illustrated using longitudinally measured atrial fibrillation data obtained through weekly trans-telephonic monitoring from an NIH sponsored clinical trial being conducted by the Cardiothoracic Surgery Clinical Trials Network.

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.

Surgical ablation of atrial fibrillation during mitral-valve surgery

BACKGROUND

Among patients undergoing mitral-valve surgery, 30 to 50% present with atrial fibrillation, which is associated with reduced survival and increased risk of stroke. Surgical ablation of atrial fibrillation has been widely adopted, but evidence regarding its safety and effectiveness is limited.

METHODS

We randomly assigned 260 patients with persistent or long-standing persistent atrial fibrillation who required mitral-valve surgery to undergo either surgical ablation (ablation group) or no ablation (control group) during the mitral-valve operation. Patients in the ablation group underwent further randomization to pulmonary-vein isolation or a biatrial maze procedure. All patients underwent closure of the left atrial appendage. The primary end point was freedom from atrial fibrillation at both 6 months and 12 months (as assessed by means of 3-day Holter monitoring).

RESULTS

More patients in the ablation group than in the control group were free from atrial fibrillation at both 6 and 12 months (63.2% vs. 29.4%, P<0.001). There was no significant difference in the rate of freedom from atrial fibrillation between patients who underwent pulmonary-vein isolation and those who underwent the biatrial maze procedure (61.0% and 66.0%, respectively; P=0.60). One-year mortality was 6.8% in the ablation group and 8.7% in the control group (hazard ratio with ablation, 0.76; 95% confidence interval, 0.32 to 1.84; P=0.55). Ablation was associated with more implantations of a permanent pacemaker than was no ablation (21.5 vs. 8.1 per 100 patient-years, P=0.01). There were no significant between-group differences in major cardiac or cerebrovascular adverse events, overall serious adverse events, or hospital readmissions.

CONCLUSIONS

The addition of atrial fibrillation ablation to mitral-valve surgery significantly increased the rate of freedom from atrial fibrillation at 1 year among patients with persistent or long-standing persistent atrial fibrillation, but the risk of implantation of a permanent pacemaker was also increased. (Funded by the National Institutes of Health and the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT00903370.).

Surgical treatment of atrial fibrillation: today's questions and answers

Although atrial fibrillation is common in cardiac surgery patients, the Cox maze IV procedure is underutilized; in contemporary practice, most cardiac surgery patients with atrial fibrillation do not receive concomitant surgical ablation. Available evidence suggests that a biatrial, energy-assisted Cox maze IV procedure restores normal sinus rhythm in two-thirds to three-quarters of patients without increasing operative risk. The best results are obtained by adherence to the correct lesion set and careful attention to perioperative management of heart rhythm and anticoagulation. To date, we have no randomized clinical trials confirming that surgical ablation improves clinical outcomes beyond restoration of sinus rhythm; however, available evidence does suggest that concomitant surgical ablation provides clinical benefit, most notably by reducing the long-term risk of stroke.

The developing pulmonary veins and left atrium: implications for ablation strategy for atrial fibrillation

The majority of cases of atrial fibrillation (AF) are the result of triggers originating in the area of the pulmonary veins. The reason for the predilection for that area remains unclear. We sought to examine the different mechanisms responsible for this observation through an extensive search of the medical literature, examining the development of the pulmonary veins, genetics of AF and left to -right cardiac chamber differentiation. Results confirm that the LAA is anatomically and embryologically different from other areas of the atrial walls and develops under distinct genetic and transcriptional pathways. Findings support an ablation strategy whose primary focus should be the creation of a 'box' lesion set, plus additional lines to prevent propagation to the left atrial appendage, the isthmus of the left atrium and the right atrium are likely to be more effective than simple pulmonary vein isolation.