While both anticoagulation with warfarin and radiofrequency ablation have been used successfully to prevent stroke and treat AF, "I think it's important to point out that surgery remains a viable option for patients with atrial fibrillation who do not respond to traditional medical therapy or who have either failed catheter ablation or are not candidates for that procedure," Damiano told a press conference here.

The Cox-Maze procedure was developed and first performed at Washington University in 1987, he said. The final version of that procedure, called the Cox-Maze III, has now been carried out on 250 patients at their institution since 1988, with more than 1500 patient-years of follow-up. "This operation to date has the best long-term success rates of any medical or surgical therapy for the treatment of AF," Damiano said. At 10 years, 96% of their patients are in normal sinus rhythm, and only one stroke has occurred.

However, the surgery is complex, requiring prolonged periods of cardiopulmonary bypass and multiple technically difficult incisions to be made in both the right and left atrium. It also carries significant morbidity in the occurrence of left atrial dysfunction and the need for pacemaker implantation, he said.

They and other groups have been working to try to simplify the procedure and make it less invasive, using ablation devices to replace the complex surgical incisions. "At the same time, we've begun to look at less extensive procedures, prompted by the success of pulmonary vein isolation in treating particularly patients with paroxysmal AF that has been seen in the EP laboratory," Damiano said.

The study presented here was a prospective multicenter trial of the combined surgical and ablation procedure, carried out at WUSM, Barnes Jewish Hospital, the Cleveland Clinic Foundation, and the Medical City Hospital in Dallas.

The 30 patients included in this trial had AF greater than six months' duration with or without organic heart disease. Ablation was done using a new energy source called bipolar radiofrequency (BRF) ablation to isolate the pulmonary vein. The BRF device consists of two 1-mm electrodes embedded in the jaws of a clamp that can be placed around target tissue.

The pulmonary veins are dissected out, and the clamp is placed around both the inferior and superior pulmonary vein. "The nice thing about this is you just deliver enough energy to create transmural lesions and then it turns itself off," Damiano said. Most patients require two or three clamp applications, at less than 10 seconds per lesion. "That's another reason it facilitates surgery, because it creates 5-cm linear ablation lines in under 10 seconds, which even the fastest surgeon can't quite keep up with," he said.

Of the 30 patients, six had bilateral pulmonary vein isolation alone, and in 24, the procedure was used to facilitate the Cox-Maze III procedure, where about half of the lesions normally done surgically were done using BRF ablation. Of the patients, 19 had paroxysmal AF and 11 persistent AF. Most patients were referred for intolerance of their AF or drug failure. Nine patients were coming to surgery for mitral valve surgery or coronary bypass grafting. Two had had a cerebrovascular accident while on adequate anticoagulation.

The right and left pulmonary veins were successfully isolated in all patients, documented by pacing before and after the procedure. There was no operative mortality and no postoperative strokes. Follow-up MRI or CT scanning at one to three months showed no evidence of pulmonary vein stenosis in any patient, and in those who underwent MRI, atrial contractility was present in every patient.

At last follow-up, 26 of 27 patients, or 96% of those available for evaluation, were in normal sinus rhythm.

Over the next few months, they hope to reduce the period of cardiopulmonary bypass required and eventually move to a completely beating-heart procedure, which they feel would reduce a great deal of the morbidity associated with it. They also hope to begin moving to a less invasive incision, perhaps using a small thoracotomy or endoscopic approach. They are hoping to better define which patients could benefit from PV ablation alone, which could certainly be done through a much less invasive approach, Damiano said.