Replacing Cox-maze incisions with radiofrequency ablation effective for controlling atrial fibrillation

October 13, 2006

St Louis, MO - Replacing the traditional "cut-and-sew" incisions of the Cox-maze procedure with bipolar radiofrequency ablation lesions is safe and effective for controlling atrial fibrillation (AF), according to the results of a new single-center study[1]. More than one year after the surgery was performed, 90% of patients undergoing the modified Cox-maze procedure were free from AF. Those undergoing pulmonary vein isolation alone fared less well, with only 59% free from AF at last follow-up.

"The traditional cut-and-sew technique has several limitations," write first author Dr Spencer Melby (Washington University School of Medicine, St Louis, MO) and colleagues in the October 4, 2006 issue of the Annals of Surgery. "Foremost, it was a technically challenging procedure, and few surgeons would perform the surgery in addition to valve or coronary surgery. The procedure added significantly to cardiopulmonary bypass and cross-clamp time. Because of its complexity, its application to the general population of patients with AF has been limited."

Melby and colleagues, with senior author and surgeon Dr Ralph Damiano (Washington University School of Medicine), say these results show that the elimination of the extensive cutting and sewing needed to make the atrial incisions of the Cox-maze simplifies the surgery, making the procedure more accessible to surgeons and patients.

Cox-maze III, although effective, is a difficult procedure

The Cox-maze procedure was developed and first performed at Washington University in 1987 (the final version is known as Cox-maze III). Although the procedure has excellent long-term efficacy in curing AF, it has not been widely practiced because of technical challenges. As the investigators note, the surgery is complex, requiring prolonged periods of cardiopulmonary bypass and multiple technically difficult incisions to be made in both the right and left atria.

To simplify the traditional Cox-maze III procedure, researchers have been evaluating strategies to modify the surgery, including replacing the surgical incisions with linear lines of ablation made by various energy sources. At Washington University, researchers examined the efficacy of using bipolar radiofrequency ablation in 130 AF patients undergoing either the modified Cox-maze procedure or pulmonary vein isolation alone (for patients at too high a risk for the complete Cox-maze procedure). Of these 130 patients, seven underwent a limited Cox-maze procedure, with two patients treated with left-sided lesions only and five with right-sided lesions only.

Investigators report that 90% of patients who underwent the Cox-maze procedure with radiofrequency ablation were free from AF recurrence at follow-up (mean follow-up 13 months). Overall, approximately one third of these patients were still being treated with antiarrhythmic medications at six and 12 months. In the pulmonary-vein-isolation group, freedom from AF was 69% at 12 months but dropped to 59% at the last known follow-up (mean follow-up 23 months). Fewer patients who underwent the pulmonary vein isolation procedure were taking antiarrhythmic medications, with only 25% and 23% taking the drugs at six and 12 months, respectively.

Among those who underwent the limited Cox-maze procedure, the cure rate was similar to the modified Cox-maze patient cohort, although the investigators point out that numbers are small and these are highly selected patients.

Patients free from AF recurrence after procedure

Time Modified Cox-maze procedure Pulmonary vein isolation p
Freedom from AF at 3 mo (%) 89 59 0.006
Freedom from AF at 6 mo (%) 88 50 0.002
Freedom from AF at 12 mo (%) 91 69 0.06
Freedom from AF at last follow-up (%) 90 59 0.003

Freedom from AF at 12 months and last follow-up

Type of AF Modified Cox-maze procedure (%) Pulmonary vein isolation (%)
Paroxysmal AF    
12-mo follow-up 80 75
Last follow-up 93 70
Permanent/persistent AF    
12-mo follow-up 94 60
Last follow-up 96 43

Perioperative complications for patients undergoing the simplified maze procedure included pulmonary embolism in one patient and stroke in another. Ten patients underwent reoperation due to bleeding, while another 10 had a permanent pacemaker put in. There was one pulmonary embolism in patients undergoing pulmonary vein isolation, and three patients had a stroke.

In their paper, the researchers point out that comparisons between the new technique and the traditional Cox-maze III procedure are difficult. There is shorter follow-up with the newer procedure as well as significant differences in patient characteristics. Patients treated with the newer, simplified procedure had more organic heart disease, worse congestive heart failure, and more concomitant procedures, the group writes, adding that longer follow-up is still needed to determine whether the ablated lesion sets are as durable as those created with the cut-and-sew technique.

Among those treated with pulmonary vein isolation were patients who were considered high-risk and not candidates for the Cox-maze or had short durations of paroxysmal AF. Despite these demographic differences, the investigators believe that the difference in success rates suggests that a significant number of patients with AF and organic heart disease would not be cured by pulmonary vein isolation alone. The group acknowledges that further studies are needed to examine the efficacy of pulmonary vein isolation in patients with lone AF.

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