The Maze procedure is a heart surgery used to treat atrial fibrillation (AFib), the most common type of irregular heart rhythm. It works by creating a pattern of scar tissue in the upper chambers of the heart that blocks the erratic electrical signals responsible for AFib. The procedure is most often performed alongside another heart surgery, such as valve repair, though it can also be done on its own.
How the Maze Procedure Works
Your heart relies on organized electrical signals to beat in a steady rhythm. In atrial fibrillation, chaotic signals fire throughout the upper chambers (the atria), causing them to quiver instead of contracting normally. This can lead to blood pooling, clot formation, stroke, and heart failure over time.
The Maze procedure interrupts those chaotic signals by creating precise lines of scar tissue in the atria. Scar tissue doesn’t conduct electricity, so the lines act like walls in a maze, forcing electrical impulses to travel along a single correct path. The result is a restored, regular heartbeat. The name comes from the maze-like pattern these scar lines form across the heart’s surface.
Types of Maze Surgery
The original technique, developed by surgeon James Cox, involved physically cutting into the heart tissue and sewing it back together to create scar lines. This “cut-and-sew” method remains the gold standard because it guarantees the scar lines extend completely through the heart wall, which is essential for blocking abnormal signals. In a study comparing the two approaches with identical scar patterns, 92% of patients who had the cut-and-sew method were free from AFib at follow-up, compared to just 62% of those treated with radiofrequency energy.
The modern version, called the Cox-Maze IV, replaces most of those surgical cuts with energy-based tools that use extreme cold (cryoablation) or heat (radiofrequency) to create the scar lines. This significantly reduces operating time while still producing strong results. The Cox-Maze IV is now the most widely performed version.
A less invasive option uses a thoracoscopic approach, where the surgeon operates through small incisions between the ribs rather than opening the chest. Because the scar lines are created from the outside surface of the heart, this version doesn’t require blood thinners during or after the procedure. That makes it particularly useful for patients who can’t safely take anticoagulants, such as those with a history of bleeding in the brain.
Who Gets a Maze Procedure
The majority of Maze procedures are performed alongside another heart surgery the patient already needs. Over half of all Cox-Maze IV surgeries are done in combination with mitral valve repair or replacement. In a review of 335 patients, 55% received a Maze procedure combined with valve surgery, while 45% had a standalone Maze. The combined operations also sometimes include tricuspid valve repair or coronary artery bypass.
Standalone Maze surgery is typically reserved for patients whose AFib hasn’t responded to medications or catheter-based ablation. It may also be the best choice for patients who can’t undergo catheter ablation for anatomical reasons, such as having a large device closing a hole between the atria or lacking the usual vein access route into the heart. Patients with a blood clot in the left atrial appendage, a small pouch on the heart where clots commonly form in AFib, are also better candidates for surgical rather than catheter-based treatment.
Success Rates Over Time
Short-term results are strong. At five years after a combined Maze and valve procedure, about 80% of patients remain free from atrial arrhythmias. Freedom from symptomatic AFib recurrence is even higher at 94% at the five-year mark, meaning some recurrences are brief or silent enough that patients don’t feel them.
Results do decline over the long term. By ten years, freedom from all atrial arrhythmias drops to around 65%, while freedom from symptomatic AFib sits at about 83%. Patients with persistent or long-standing AFib before surgery tend to fare somewhat worse than those with the intermittent (paroxysmal) form. These numbers mean ongoing heart rhythm monitoring remains important even years after a successful surgery.
Risks and Pacemaker Rates
The most notable risk specific to the Maze procedure is developing a slow heart rhythm afterward that requires a permanent pacemaker. The scar lines that block AFib signals can also interfere with the heart’s normal pacing system. Reported pacemaker rates vary widely depending on the study and the type of surgery performed alongside the Maze. Early pacemaker implantation within 30 days occurs in roughly 13% of patients undergoing a combined Maze and valve operation. By five years, about 22% of these patients have a pacemaker, rising to 27% by eight years.
These rates are significantly higher than for patients undergoing valve surgery alone, where pacemaker rates sit closer to 5-13%. The risk is highest when the Maze is combined with surgery on both the mitral and tricuspid valves, since the heart’s natural pacemaker and conduction pathways run near those structures.
Recovery and What Comes After
Because the Maze procedure involves open-heart surgery (or at minimum, general anesthesia with chest access), recovery takes several weeks. Patients can expect a hospital stay followed by a gradual return to normal activity over one to three months, depending on whether additional procedures like valve surgery were performed at the same time.
All patients are placed on blood thinners for at least three months after surgery to reduce stroke risk while the scar lines heal and the heart’s rhythm stabilizes. After that initial period, the decision to continue anticoagulation is individualized based on factors like stroke risk score, whether normal rhythm has been maintained, and the treating cardiologist’s judgment. Anti-arrhythmic medications are also commonly used in the early months and then tapered if the heart stays in rhythm.
The heart’s electrical system can take time to settle after surgery, so occasional irregular beats or short episodes of AFib in the first few months don’t necessarily mean the procedure failed. The three-to-six-month window is generally considered a “healing period” before long-term rhythm success is assessed.