The MAZE procedure or ablation procedure is used by surgeons to treat atrial fibrillation. It has been modified many times over the years from the original procedure where the atrium was cut and then sewn back together to a much easier procedure with lower risk. In its common form, an energy source (most commonly radiofrequency energy) is used to create lesions or scar tissue in the atrium, which sets up electrical barriers in the heart. The goal is to channel the electrical flow in the heart and eliminate the chaotic rhythm of atrial fibrillation.

When successful, it can obliterate atrial fibrillation and return the heart to a normal rhythm. It is most frequently performed concomitantly with valve surgery or coronary artery bypass surgery, but can also be performed as a stand alone procedure through small incisions.

All patients undergoing heart surgery who have atrial fibrillation should be considered for concomitant ablation, although it is not indicated in every patient. Furthermore, there are select patients with lone atrial fibrillation and no other heart problems that should be considered for minimally invasive ablation (see Figure 4, below), either surgically or in the cath lab. The surgical option carries the advantage of eliminating the left atrial appendage, which is where 91 % of the clots in the heart occur. This may reduce the risk of stroke further than ablation that leaves the left atrial appendage intact.

A clamp is placed across the left atrium. Radiofrequency energy is emitted between the two jaws creating a lesion and electrical barrier. A complete set of lesions can be created in less than 15 minutes in typical cases. A stapling device is then used to amputate the left atrial appendage. This eliminates the most common site of clot formation in the heart. The left atrial appendage is not necessary for proper function of the heart and can be harmful to patients with atrial fibrillation.

The MAZE procedure has many benefits. The most important to patients is the possibility of getting off the blood thinners, such as Coumadin (warfarin), which are necessary for many patients with atrial fibrillation. Other benefits include decreasing the risk of stroke, improved cardiac performance, decreased symptoms (including palpitations and syncope) and possibly prolonged survival, although the last benefit is theoretical and has not yet been proved.