While indications for atrial fibrillation (AF) patients have changed considerably over the last two decades, using certain surgical ablation procedures to treat AF can have a cure rate of more than 90 percent, according to a presentation Jan. 14 at the 15th annual Boston AF Symposium (BAFS).
Catheter ablation is indicated for patients with symptomatic AF and those undergoing surgery for an additional cardiac indications, explained Ralph Damiano, Jr., MD, chief of cardiac surgery at the Washington University School of Medicine in St. Louis.
Patients who undergo surgery AF represent 5 percent of the surgical volume received at all facilities. This patient population is tremendously undertreated, and "surgical ablation should be performed if it doesn’t add significantly to operative morbidity and mortality,” Damiano said.
He referenced the Cox-Maze (CM) procedure, an open-heart procedure that "amputates the left atrial appendage and may be part of why it’s so effective at preventing thromboembolic stroke.”
A clinical trial, conducted by Damiano and colleagues, studied the long-term efficacy of the CM procedure in more than 1,200 AF patients. At six years, 90 percent of patients were free from AF. At 10 years, 97 percent of these patients were free of AF, while 90 percent were off coumadin.
Damiano referenced another of his studies presented at the 2009 Heart Rhythm Society conference that examined stroke rates after a CM procedure between those on warfarin and those off the drug. After a 6.5-year follow-up, the risk of stroke in patients on the drug was “significantly higher” than those taken off the drug.
“While there’s some criticism that our follow-up was patient driven and medical record driven,” he said, the “operation with removal of the appendage is extraordinarily effective in preventing a stroke and perhaps it may be an indication for surgical ablation.”
Damiano and colleagues at Washington University have set out to simplify the CM III procedure by replacing surgical incisions with transmural ablation lines, while at the same time preserving the traditional lesion set. During this research, Damiano said the facility “favored bipolar radiofrequency clamps.”
In the clinical trial performed at the facility's animal lab, the use of radiofrequency clamps during ablation was “virtually 100 percent reliable in creating transmural ablation that isolated the pulmonary vein in five to 10 seconds,” said Damiano. In humans, the same procedure would take twice as long and be “very reliable."
The use of these devices, according to Damiano, “absolutely eliminates the room for collateral damage.” In fact, in a clinical study performed at Washington University, during 350 ablation procedures using radiofrequency clamps, not one case of pulmonary vein stenosis arose.
In a study of 263 patients, Damiano and colleagues found that after a CM IV procedure and a one-year follow-up, 93 percent of patients were free of AF and 70 percent were free of AF and off antiarrythmic drugs. "More than 80 percent of patients have had prolonged monitoring at six, eight and 12 months. This operation works. In my opinion, this has changed the face of ablation."
Moving forward, Damiano suggests that the best surgical procedure for treating AF could be a combination of epicardial and endocardial ablation techniques because the single procedure could give a “one-time success.”
For future techniques, Damiano suggests that the facility come up with an intraoperative approach where ablation lines are performed, and tested, to examine whether they are transmural. He said that this would “require a more sophisticated [hybrid] approach" along with cooperation between electrophysiologists and surgeons to properly manage and follow patients.
Lastly, Damiano suggested that minimally invasive AF surgery techniques need to be patient-specific rather than a single operation.