What is the Maze procedure used for in treating atrial fibrillation?

The Maze Procedure for Atrial Fibrillation

The Maze procedure is a surgical intervention specifically designed to treat atrial fibrillation by creating strategic incisions or ablation lines in the atrial tissue to disrupt abnormal electrical pathways and restore normal sinus rhythm. 1

Mechanism and Development

• The Maze procedure was developed based on the hypothesis that reentry is the predominant mechanism responsible for the development and maintenance of atrial fibrillation 1
• The procedure creates barriers to conduction within the atria through strategic incisions or ablation lines, limiting the myocardium available to propagate reentrant wave fronts 1
• The name "Maze" comes from the concept of creating a geographical maze in the heart tissue that guides electrical impulses along a specific path 1
• The procedure has evolved through three iterations (Maze I, II, and III) with the Cox Maze III becoming the standard surgical approach for AF treatment 1

Types and Evolution

• The original "cut-and-sew" technique (Cox Maze III) ensures transmural lesions to isolate the pulmonary veins, connect these dividing lines to the mitral valve annulus, and create electrical barriers in the right atrium 1
• The Cox Maze IV is less invasive, using radiofrequency or cryoablation to replicate the surgical lines of ablation instead of the traditional "cut-and-sew" approach 1
• The procedure can be performed as:
  • A concomitant procedure during other cardiac surgeries (Class IIa recommendation) 1
  • A stand-alone procedure for selected patients with highly symptomatic AF not well managed with other approaches (Class IIb recommendation) 1

Efficacy

• Success rates of around 95% over 15 years of follow-up have been reported in patients undergoing mitral valve surgery with concomitant Maze procedure 1
• Other studies suggest success rates around 70% 1
• In a study of 282 patients who underwent the Cox Maze IV procedure, freedom from atrial tachyarrhythmias was 89%, 93%, and 89% at 3,6, and 12 months, respectively 1
• Freedom from atrial tachyarrhythmias without antiarrhythmic drugs was 63%, 79%, and 78% at 3,6, and 12 months, respectively 1

Benefits

• Restores sinus rhythm and atrial systole 2
• Reduces the risk of thromboembolism by maintaining atrial transport function 3
• Reduces the need for anticoagulant medications after successful procedure 4
• Improves hemodynamics by restoring synchronized atrioventricular contraction 2, 3
• Eliminates symptoms associated with irregular heartbeat 2

Risks and Complications

• Mortality risk is less than 1% when performed as an isolated procedure, but higher when combined with other cardiac surgeries 1
• Potential complications include:
  • Need for permanent pacemaker implantation (particularly with right-sided lesions) 1
  • Recurrent bleeding requiring reoperation 1
  • Impaired atrial transport function 1
  • Delayed atrial arrhythmias (especially atrial flutter) 1
  • Atrioesophageal fistula (rare but serious) 1
  • Fluid retention due to reduced release of atrial natriuretic peptide 1
  • Transient reduction in left and right atrial transport function 1

Patient Selection

• The procedure is typically reserved for patients with:
  • Atrial fibrillation refractory to medical treatment 5, 6
  • History of systemic embolism 5
  • Contraindications for anticoagulant treatment 5
  • Patients already undergoing cardiac surgery for other indications 1
  • Highly symptomatic AF not well managed with other approaches 1

Current Status in Clinical Practice

• Despite its high success rate, the traditional Maze operation has not been widely adopted outside of patients already undergoing cardiac surgery due to the need for cardiopulmonary bypass 1
• Less invasive modifications including thoracoscopic and catheter-based epicardial techniques are under investigation 1
• The Society of Thoracic Surgeons Adult Cardiac Surgery Database from 2005 to 2010 recorded 91,801 AF surgical ablations, of which only 5.3% were stand-alone procedures 1

Cost-Effectiveness

• A randomized controlled trial found that the Maze procedure was not cost-effective at £30,000 per QALY over 2 years 4
• The mean additional cost of the maze procedure was £3,533 with no significant improvement in quality-adjusted life years 4

The Maze procedure remains an important surgical option for treating atrial fibrillation, particularly for patients undergoing cardiac surgery or those with symptomatic AF refractory to other treatments. While it effectively restores sinus rhythm, careful patient selection is essential to balance the benefits against the risks and costs of this invasive procedure.