Mini Maze Procedure Success Rates
Reported results for the mini maze procedure have varied by center due to differences in measuring success and because the procedure keeps evolving. In addition, unlike catheter ablation, which has had a predominant energy source that has been relatively consistent from center to center, the mini maze procedure has involved a wide variety of energy sources that have produced widely-varying results.
While mini maze procedure success rates are typically in the 80%–90% range for paroxysmal atrial fibrillation and in the 50%–75% range for persistent and longstanding persistent atrial fibrillation, some energy sources have produced lower success rates. Newer lesions sets are producing better results, especially for persistent and longstanding persistent afib.
Most published mini maze procedure studies have been from smaller studies at single centers. Two studies, done in 2007 and earlier and published in 2008, produced the following results:
- In a 2007 study at Nebraska Heart Hospital (Lincoln, NE), 20 (91%) of 22 paroxysmal patients were afib-free without antiarrhythmic drugs at 12–27 months as reported by Holter monitor follow-up. There were no strokes and no patient mortality.1
- In a 2008 report presented at the Society of Thoracic Surgeons (STS) annual meeting, of 74 patients who had undergone a mini maze procedure that included pulmonary vein isolation, ganglionic plexi, Ligament of Marshall, and left atrial appendage removal, 83.7% with paroxysmal afib and 56.5% with persistent and longstanding persistent afib were successful.2
One particularly interesting point made in the study presented at STS was just how much numbers may be skewed when using only random ECGs for followup. At six months, random ECGs declared 100% of paroxysmal patients to be in normal sinus rhythm (NSR), but it was only 83.7% when evaluated by Holter monitor, event monitor, or pacemaker interrogation. For persistent and longstanding persistent, it was even more dramatic, at 81.5% vs. 56.5%. This confirmed previous reports of up to a 40% difference in atrial fibrillation detection between ECGs and implanted devices.2
When this study was published, it included a discussion of how to revise the mini maze procedure to accomplish a left-sided Cox Maze III lesion set for use on persistent and longstanding persistent afib.2 That procedure has now been implemented and data is being collected. You can see a video of the procedure at Surgeon Discusses Evolution and Future of Atrial Fibrillation Maze Procedure.
In a recent study of the newest procedure, the totally thoracoscopic maze procedure, that was done strictly on longstanding persistent (91%) and persistent (9%) patients, 21 of the 24 (87.5%) that had reached six months were in sinus rhythm and not on antiarrhythmic drugs. The three that failed had done so upon withdrawal of antiarrhythmic drugs three months after the operation and all had been in longstanding persistent atrial fibrillation for 3 years or more. No one needed a pacemaker and there was no atrial flutter.3
Fortunately, the HRS Consensus Statement4 has created more consistency in measuring results from catheter ablation and surgical ablation, which should make future results easier to compare.
It will still be necessary to know more about the specific energy source and devices used. The studies above all used radiofrequency energy, but studies are underway with several energy sources and devices. See Surgical Ablation Energy Sources for more about the mini maze procedure energy sources.
Learn about Mini Maze Procedure Risks.