Addition of one extra ablation to the radiofrequency-clamp Cox-Maze procedure reduces short-term and long-term recurrence of atrial flutter and fibrillation, according to an article in the April issue of the Journal of Thoracic and Cardiovascular Surgery.

Heart surgeons at Washington University School of Medicine in St. Louis, where the original procedure was developed in the 1980s, found that adding the simple 10-20 second step produced a significant improvement in the outcome for the surgical treatment of atrial fibrillation.

The Cox-Maze procedure is highly effective, offering the best long-term cure rate for persistent atrial fibrillation. The surgeons added one ablation to the series typically made during the Cox-Maze procedure and that short step improved how well patients did after surgery. As a result, they recommend using this extra ablation in all patients undergoing the procedure.

"The single additional ablation creates what we call a box lesion," explained Ralph J. Damiano Jr., MD, the John Shoenberg Professor of Surgery at the School of Medicine. "The box lesion surrounds and electrically isolates the pulmonary veins and the posterior left atrial wall from the rest of the left atrium. Our study shows excellent success when using the box lesion, and we recommend it for any patient with long-standing atrial fibrillation."

Led by Damiano, also chief of cardiac surgery at the School of Medicine and a cardiac surgeon at Barnes-Jewish Hospital, the Washington University surgeons revolutionized treatment in 2002 by helping develop a radiofrequency clamp that creates the ablation lines needed to reroute electrical impulses in the heart. The clamp directs radiofrequency energy into the heart muscle and creates a full-thickness scar.

The radiofrequency clamp procedure is quicker and easier than the original "cut and sew" Cox-Maze procedure, which was developed by James Cox, M.D., at Washington University in 1987. The original procedure relied on a complex series of 10 incisions in the heart muscle, creating a "maze" to channel errant electrical impulses where they should go. In the newer version, called Cox-Maze IV, most of these incisions were replaced by radiofrequency ablations, reducing the operation from an average of 90 minutes to about 30 minutes.

The current study involved two groups of patients. One group underwent radiofrequency ablation-assisted Cox-Maze IV procedures without a box lesion and the other with a box lesion. The box lesion group had a 48 percent lower occurrence of atrial flutter and fibrillation in the first weeks after surgery. These patients also had shorter hospital stays (average, 9 days) than patients who had the standard Cox-Maze IV procedure (average, 11 days).

Three months after surgery, 95 percent of patients who had the box lesion had no signs of arrhythmia, while only 85 percent of the patients who had the standard Cox-Maze IV procedure were free from arrhythmia. By 6 and 12 months postsurgery, all patients in the box lesion group were free from arrhythmia compared with 90 percent of the other group, a difference that was not statistically significant.

"We also saw that the use of antiarrhythmic drugs was lower after three and six months in those who received a box lesion," Damiano said. "These drugs can have serious side effects, and if patients can stop using them they often feel better. Overall, the use of the box lesion set was associated with shorter hospitalization, fewer medications and reduced recurrence of atrial fibrillation. We were very pleased with these results."