Success rate for mini-maze procedure

AMSTERDAM, THE NETHERLANDS. The Cox maze procedure was the first surgical procedure (first performed in 1987) aimed at curing atrial fibrillation (AF) by creating a maze of scar tissue that conducted the electrical impulse initiating the heartbeat directly from the SA (sino-atrial) node to the AV (atrio-ventricular) node, while at the same time interrupting any “rogue” circuits. A major drawback of the procedure is that it is open-heart surgery and is performed on the non-beating heart, thus requiring the use of a heart/lung machine with its attendant potentially serious adverse effects.

The so-called mini-maze procedure also involves creating lesions epicardially (on the outside of the heart wall), but access to the heart is through incisions between the ribs rather than through open-heart surgery. Although maze-like lesions can be created during the procedure, it usually focuses on pulmonary vein isolation with lesions being created using radiofrequency (RF) energy. The procedure is done on the beating heart and does not require the use of a heart/lung machine.

Our 2007 Ablation/Maze Survey included 31 mini-maze procedures. The complete success rate (no arrhythmia, no antiarrhythmic drugs) at 6 months was 57% (69% for top-ranked institutions) and the partial success rate (no arrhythmia, but still on antiarrhythmics) was 7% (15% for top-ranked institutions). The survey concluded that a mini-maze procedure performed by a top-ranked cardiac surgeon provides the second-best chance of being cured of AF with one single procedure (the full maze procedure has the best success rate). It is also likely that even a mini-maze performed by a less than top-ranked surgeon will have a substantially better outcome than a single pulmonary vein isolation procedure performed by a less than top-ranked electrophysiologist. However, the risk of an adverse event accompanying the mini-maze procedure is somewhat higher than for RF ablation procedures.

A group of Dutch cardiac surgeons has now confirmed that above conclusion. They reviewed 23 studies presenting success rates for RF-powered mini-maze procedures performed on 842 patients between 2005 and 2011. The average complete success rate at 6 months post-procedure was 64% and the partial success rate was 11%. At the 1-year follow-up, complete success rate was 69% and partial success rate 10%. The 1-year success rate for paroxysmal AF was 75% - considerably higher than for persistent AF (67%) and long-standing persistent AF (43%). The rate of procedure-related complications at 14% was substantially higher than reported for catheter ablation. Mortality was 0.4%, the risk of pacemaker implantation 1.4%, and stroke risk 0.5%. The risk of surgical complications was 3.2%, post-surgical complications 3.2%, and cardiac complications 2.6%.
Krul, SPJ, et al. Navigating the mini-maze: systematic review of the first results and progress of minimally-invasive surgery in the treatment of atrial fibrillation. International Journal of Cardiology, 2011 [Epub ahead of print]

Editor’s comment: The Dutch study confirms that the chance of being cured of afib with a single procedure is higher for the mini-maze than for a catheter ablation procedure. However, while the mini-maze cannot be repeated, a catheter ablation can, with multiple procedure success rates equal to, or surpassing, that of a single mini-maze procedure.