Left Atrial vs. Bi-Atrial Maze Operation
Abstract & Commentary
Synopsis: A solely left atrial ablation procedure that isolates the pulmonary veins and left atrial appendage can restore sinus rhythm in many patients with chronic or recurrent atrial fibrillation.
Source: Deneke T, et al. J Am Coll Cardiol. 2002;39: 1644-1650.
Atrial fibrillation is a common finding in people undergoing cardiac surgery. In this report, Deneke and colleagues describe their results using cooled-tip radiofrequency (RF) ablation procedures to treat atrial fibrillation in 70 patients who underwent cardiac surgical procedures at their institution. They report results using both a bi-atrial and a left atrial-only RF ablation technique. The groups, however, were not randomly determined.
There were 21 patients who had a left atrial ablation procedure that involved the placement of RF ablation lines around the separate ostia of each pulmonary vein. These circles were then joined with additional lines to connect the ostial ablation rings and then to the mitral annulus and left atrial appendage. Patients who had a bi-atrial procedure had several additional ablation lines placed in the right atrium. After operation, patients were maintained on low-dose sotalol as an antiarrhythmic drug for 6 months and then switched to metoprolol. Cardioversion was performed in only those patients who were in permanent atrial fibrillation 6 months after the operation. The operations reported here were performed between March 1997 and February 2001.
The study group included 70 patients. Twenty-one underwent a left atrial procedure and 49 underwent a bi-atrial procedure. The groups were not comparable. Patients who underwent a bi-atrial procedure were more likely to undergo mitral valve replacement or repair (30/49), whereas only 8 of 21 patients with left atrial procedures had mitral valve repair or replacement. Among the patients who underwent a left atrial procedure, 63% were in sinus rhythm at 1 month, with 82% in sinus rhythm after 6 months. Among the patients who underwent bi-atrial procedures, 55% were in sinus rhythm at 1 month and 68% after 6 months. Most patients were discharged from the hospital in sinus rhythm and a few converted early after discharge. There was only 1 spontaneous conversion to sinus rhythm more than 6 months after the procedure. Patients who had not converted after 6 months were cardioverted back to sinus rhythm. However, only 1 of 12 patients who were cardioverted maintained sinus rhythm long-term. Two patients who underwent the bi-atrial procedure developed atypical atrial flutter during follow-up. Atrial flutter was not seen in the group of patients who underwent left atrial procedures.
Doppler echocardiography was performed in selected patients who were in sinus rhythm at 6 months. Bi-atrial contraction was documented using transthoracic Doppler echocardiography in 92% of the study patients who underwent left atrial procedures and in 79% of the study patients who underwent bi-atrial procedures.
Permanent pacemakers were required in only 2 patients, both of whom underwent bi-atrial procedures. Intra-operative and peri-operative complications were uncommon and distributed with approximately equal frequency in both groups. However, the cardiopulmonary bypass time was prolonged by the addition of the right atrial ablations. There was no statistically significant difference in survival or late complications seen after the 2 procedures.
Deneke et al concluded that a solely left atrial ablation procedure that isolates the pulmonary veins and left atrial appendage can restore sinus rhythm in many patients with chronic or recurrent atrial fibrillation. The efficacy of a left-sided procedure ablation lesion set appears to be similar to that obtained using a bi-atrial approach. Bi-atrial contraction and a low incidence of late atrial flutter are seen with the simpler, left-sided procedure.
Comment by John P. DiMarco, MD, PhD
The Maze procedure was first proposed as a surgical treatment for patients with atrial fibrillation more than 15 years ago. However, even after several modifications, the Maze procedure requires multiple atrial incisions that result in a long operative procedure. During the last several years, RF application using a simple, hand-held probe has been introduced as an alternate technique. Ablation with this system is easier to perform and does not prolong operative time as much as the Maze technique. It is now gaining popularity among cardiac surgeons as an adjunct to surgery in patients with history of atrial fibrillation.
The results described in this paper are quite promising. Despite the fact that patients in both groups had experienced atrial fibrillation for years, a high proportion of them were able to maintain sinus rhythm with intact atrial contractile function during long-term follow-up. It is difficult to compare the 2 procedures described since the patients in this series who underwent bi-atrial ablation procedure had a higher prevalence of mitral valve disease. However, the data presented here suggesting that left atrial procedures alone may well be effective is encouraging. The left atrial approach had a high success rate and late atrial flutter was not a problem. The paper suggests that left atrial ablation only should be the preferred approach. Even if additional right-sided ablation needed to be performed in patients with recurrent atrial flutter after their operation, these right-sided procedures should be relatively easy to accomplish using standard catheter approaches.
The data presented here suggest that it is time for all surgeons who operate on patients with atrial fibrillation to consider learning this technique. However, it remains to be shown that stroke rates will actually be lower if RF ablation restores the patient to sinus rhythm. Until long-term follow-up data become available that show that anticoagulation is not necessary, I plan to continue anticoagulation long-term in these patients.
Dr. DiMarco is Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville.
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