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Epicardial microwave ablation of permanent atrial fibrillation during a coronary bypass and/or aortic valve operation: Prospective, randomised, controlled, mono-centric study

M. Knaut, S. Kolberg, S. Brose, F. Jung
[Applied Cardiopulmonary Pathophysiology 14: 220-228, 2010]


Atrial fibrillation (AF), one of the most common arrhythmias, is the aetiology behind a high percentage of strokes. Recently simplified ablation procedures became more relevant in the surgical treatment of AF. One advantage of microwave ablation (MW) is that it can be used epicardially. We report our results of a prospective, randomized, controlled, mono centre trail. In two arms, with and without ablation, we treated patients with documented permanent atrial fibrillation with an indication for cardiac surgery, where opening of the left atrium was not required.
Methods: Patients, who were scheduled for aortic valve replacement and/or coronary artery bypass grafting suffering from permanent AF, were included in the registry. After inclusion the patients were randomized either to epicardial MW (EMW) as a concomitant procedure during their operation (Group A) or equivalent operations without ablation therapy (group B). Follow-up was one year. EMW was performed under extracorporeal circulation on the beating heart creating a box lesion including the anterior part of the pulmonary veins with connection lines on the roof and bottom of the left atrium and an additional line to the left atrial appendage.
Results: 45 patients (17 female/ 28 male) with AVD and/or CAD and pAF were included. Preoperative duration of pAF was 5.2 years (0.1-45 years). Preoperative data were as follows: mean age: 74 years (63-83 years), mean ejection fraction: 56% (3083%), left atrial diameter: 46.1mm (40-59mm). 20 patients got aortic valve replacement, 17 had CABG, and 8 operations were combined procedures (AVR and CABG).
All ablation procedures were performed on-pump beating heart. We observed no device related complications. During the follow-up, restoration of the sinus rhythm rate after one year is 52.4% in the ablated patients in contrast to 10.5% in the control group. The 30-day survival rate in group A was 87.5% and 95.2% in group B (n.s.). Pacemaker implants after one year were required in 12.5 % in group A and 25% in group B.
Conclusion: Our results demonstrate that EMW is an effective treatment option for patients with permanent AF. The procedure is less invasive than the endocardial approach and prolongs concomitant heart surgery only minimally without lengthening of the ischemic time. We think, that EMW ablation is a promising concept with a good benefit/risk ratio for the treatment of pAF, especially in patients where opening of the left atrium is not required as part of the original procedure. A more extended lesion line concept, closer to the classic Maze procedure lines is suggested to achieve higher success rates.
EMW has become part of our daily routine for the treatment of AF in patients scheduled for bypass grafting and/or aortic valve replacement.

Key words: prospective randomised trial, epicardial ablation, microwave energy, coronary artery bypass grafting, aortic valve replacement and permanent atrial fibrillation

Correspondence address:
PD Dr. M. Knaut
Department of Cardiac Surgery
University of Technology Dresden

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