What is the Maze procedure for treating atrial fibrillation?

What is the Maze Procedure?

The Maze procedure is a surgical intervention that treats atrial fibrillation by creating strategic incisions or ablation lines in the atrial tissue to disrupt abnormal electrical pathways and restore normal sinus rhythm, with success rates approaching 95% over long-term follow-up when performed correctly. 1, 2

Mechanism and Rationale

The procedure is based on the principle that reentry circuits are the predominant mechanism responsible for atrial fibrillation. 1, 2 The surgical approach creates barriers to conduction within the atria through strategic incisions or ablation lines, limiting the myocardium available to propagate reentrant wave fronts. 1, 2 The name "Maze" derives from creating a geographical maze in the heart tissue that guides electrical impulses along a specific path while preventing sustained atrial fibrillation. 1, 2

Evolution of the Technique

Original Cut-and-Sew Approach (Cox Maze III)

• The traditional technique 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 that prevent macroreentrant rhythms. 1, 2
• This approach went through three iterations (Maze I, II, and III), with the Cox Maze III becoming the standard surgical procedure. 1
• The earlier versions (Maze I and II) were associated with high rates of pacemaker implantation and are no longer performed. 1

Modern Approach (Cox Maze IV)

• 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, 2
• This modification reduces operative complexity while maintaining efficacy. 1

Clinical Efficacy

Success Rates

• Freedom from atrial tachyarrhythmias reaches 89-93% at 3-12 months when performed as the Cox Maze IV procedure. 1, 2
• Freedom from atrial tachyarrhythmias without antiarrhythmic drugs is 78-79% at 6-12 months. 1, 2
• When combined with mitral valve surgery, success rates approach 95% over 15 years of follow-up. 1, 2
• The overall success rate in curing atrial fibrillation has been documented at 99% in specialized centers. 3

Functional Outcomes

• Left atrial transport function is maintained in 93% of patients long-term. 3
• Right atrial function is preserved in 99% of patients. 3
• The procedure does not cause permanent damage to the sinus node. 3

Guideline Recommendations

Class IIa (Reasonable to Perform)

• An AF surgical ablation procedure is reasonable for selected patients with AF undergoing cardiac surgery for other indications. 1
• For symptomatic patients with paroxysmal or persistent AF who are undergoing valvular surgery, surgical pulmonary vein isolation or a maze procedure can be beneficial to reduce symptoms and prevent recurrent arrhythmias. 1

Class IIb (May Be Considered)

• A stand-alone AF surgical ablation procedure may be reasonable for selected patients with highly symptomatic AF not well managed with other approaches. 1
• A concomitant maze procedure or pulmonary vein isolation may be considered at the time of mitral valve repair or replacement in patients with paroxysmal AF that is symptomatic or associated with a history of embolism on anticoagulation. 1

Patient Selection Criteria

The procedure is typically reserved for: 2, 4, 5

• Patients with atrial fibrillation refractory to medical treatment
• History of systemic embolism despite anticoagulation
• Contraindications for anticoagulant treatment
• Patients already undergoing cardiac surgery for other indications
• Highly symptomatic AF not well managed with catheter ablation or medications

Risks and Complications

Mortality

• Operative mortality is less than 1% when performed as an isolated procedure. 1, 2
• Overall operative mortality is 2-3% when including concomitant high-risk cardiac surgical procedures and redo cases. 1, 3

Major Complications

• Need for permanent pacemaker implantation (particularly with right-sided lesions). 1, 2
• Recurrent bleeding requiring reoperation. 1, 2
• Impaired atrial transport function. 1, 2
• Delayed atrial arrhythmias, especially atrial flutter. 1, 2
• Atrioesophageal fistula. 1, 2

Current Clinical Practice

Limited Adoption

• Despite high success rates, the traditional Maze operation has not been widely adopted outside of patients already undergoing cardiac surgery due to the need for cardiopulmonary bypass. 1, 2
• 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, 2

Emerging Modifications

• Less invasive modifications including thoracoscopic and catheter-based epicardial techniques are under investigation. 1, 2
• Minimally invasive approaches without cardiopulmonary bypass have been performed in selected patients. 3

Postoperative Management

Anticoagulation Requirements

• Anticoagulation therapy is reasonable for at least 3 months after the procedure, even with successful rhythm conversion. 1
• Warfarin with target INR 2.5-3.5 is recommended for at least 3 months post-procedure if atrial fibrillation persists. 6
• The Maze procedure does not eliminate the need for anticoagulation in the immediate postoperative period, particularly if preoperative atrial fibrillation duration was >3 months. 6

Important Caveat

• Persistence of atrial fibrillation occurs in 80% of patients who had preoperative atrial fibrillation ≥3 months, necessitating prolonged anticoagulation despite the procedure. 6, 7