Efficacy of Oral Anticoagulation in Stroke Prevention among Sinus-Rhythm Patients Who Lack Left Atrial Mechanical Contraction after Cryoablation

Amaze: a double-blind, multicentre randomised controlled trial to investigate the clinical effectiveness and cost-effectiveness of adding an ablation device-based maze procedure as an adjunct to routine cardiac surgery for patients with pre-existing atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) can be treated using a maze procedure during planned cardiac surgery, but the effect on clinical patient outcomes, and the cost-effectiveness compared with surgery alone, are uncertain.

OBJECTIVES

To determine whether or not the maze procedure is safe, improves clinical and patient outcomes and is cost-effective for the NHS in patients with AF.

DESIGN

Multicentre, Phase III, pragmatic, double-blind, parallel-arm randomised controlled trial. Patients were randomised on a 1 : 1 basis using random permuted blocks, stratified for surgeon and planned procedure.

SETTING

Eleven acute NHS specialist cardiac surgical centres.

PARTICIPANTS

Patients aged ≥ 18 years, scheduled for elective or in-house urgent cardiac surgery, with a documented history (> 3 months) of AF.

INTERVENTIONS

Routine cardiac surgery with or without an adjunct maze procedure administered by an AF ablation device.

MAIN OUTCOME MEASURES

The primary outcomes were return to sinus rhythm (SR) at 12 months and quality-adjusted life-years (QALYs) over 2 years after randomisation. Secondary outcomes included return to SR at 2 years, overall and stroke-free survival, drug use, quality of life (QoL), cost-effectiveness and safety.

RESULTS

Between 25 February 2009 and 6 March 2014, 352 patients were randomised to the control (n = 176) or experimental (n = 176) arms. The odds ratio (OR) for return to SR at 12 months was 2.06 [95% confidence interval (CI) 1.20 to 3.54; p = 0.0091]. The mean difference (95% CI) in QALYs at 2 years between the two trial arms (maze/control) was -0.025 (95% CI 0.129 to 0.078; p = 0.6319). The OR for SR at 2 years was 3.24 (95% CI 1.76 to 5.96). The number of patients requiring anticoagulant drug use was significantly lower in the maze arm from 6 months after the procedure. There were no significant differences between the two arms in operative or overall survival, stroke-free survival, need for cardioversion or permanent pacemaker implants, New York Heart Association Functional Classification (for heart failure), EuroQol-5 Dimensions, three-level version score and Short Form questionnaire-36 items score at any time point. Sixty per cent of patients in each trial arm had a serious adverse event (p = 1.000); most events were mild, but 71 patients (42.5%) in the maze arm and 84 patients (45.5%) in the control arm had moderately severe events; 31 patients (18.6%) in the maze arm and 38 patients (20.5%) in the control arm had severe events. The mean additional cost of the maze procedure was £3533 (95% CI £1321 to £5746); the mean difference in QALYs was -0.022 (95% CI -0.1231 to 0.0791). The maze procedure was not cost-effective at £30,000 per QALY over 2 years in any analysis. In a small substudy, the active left atrial ejection fraction was smaller than that of the control patients (mean difference of -8.03, 95% CI -12.43 to -3.62), but within the predefined clinically equivalent range.

LIMITATIONS

Low recruitment, early release of trial summaries and intermittent resource-use collection may have introduced bias and imprecise estimates.

CONCLUSIONS

Ablation can be practised safely in routine NHS cardiac surgical settings and increases return to SR rates, but not survival or QoL up to 2 years after surgery. Lower anticoagulant drug use and recovery of left atrial function support anticoagulant drug withdrawal provided that good atrial function is confirmed.

FURTHER WORK

Continued follow-up and long-term clinical effectiveness and cost-effectiveness analysis. Comparison of ablation methods.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN82731440.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 19. See the NIHR Journals Library website for further project information.

Cox maze IV versus left atrial reduction for atrial contraction restoration

Background

The Cox maze procedure is the gold-standard concomitant surgical procedure to restore sinus rhythm in rheumatic mitral valve disease with atrial fibrillation. Left atrial reduction surgery was found to be beneficial for rhythm conversion, but no study has investigated its efficacy compared to the Cox maze procedure for atrial contractility restoration. We aimed to compare the early success rate of left atrial contractility restoration with the Cox maze procedure and left atrial reduction in rheumatic subjects.

Methods

Preoperative and within one-month postoperative electrocardiograms and echocardiograms of patients who underwent a Cox maze IV procedure or left atrial reduction with mitral valve surgery were compared. Effective atrial contraction was defined as A wave peak velocity ≥10 cm·s−1 or atrial filling fraction ≥20%.

Results

Ninety patients (mean age 40.6 ± 10.2 years, 66.7% female) were divided equally into group A (Cox maze IV) and group B (left atrial reduction). The early sinus rhythm conversion rate was 64.4% versus 24.4% ( p < 0.001) in groups A and B, respectively. In patients with restored sinus rhythm, contractility was restored in 41.4% and 36.4% ( p = 1.000). Postoperative left atrial volume index ≤76 mL·m−2 was an independent variable associated with early atrial contractility restoration in both groups (prevalence rate 0.97, p = 0.007).

Conclusions

In rheumatic subjects, the early sinus rhythm conversion rate was significantly higher after Cox maze IV compared to left atrial reduction, but for restoring left atrial contractility, left atrial reduction was not inferior to Cox maze IV.