New laser balloon catheter "lights up" for better isolation of pulmonary veins during AF ablation

May 10, 2011

San Francisco, CA - The use of an investigational visually guided laser balloon (CardioFocus, Marlborough, MA) resulted in higher rates of pulmonary vein isolation in the treatment of atrial fibrillation, according to a study testing first experiences with the new device[1]. Presenting data last week at the Heart Rhythm Society (HRS) 2011 Scientific Sessions , investigators suggest that better isolation can reduce the incidence of recurrent atrial fibrillation related to pulmonary vein reconnections.

Dr Vivek Reddy

Speaking with heartwire , lead investigator Dr Vivek Reddy (Mount Sinai School of Medicine, New York) pointed to numerous studies showing a slow but steady decline in arrhythmia-free survival after the procedure, noting the "results are not as great we'd like." In one study by a group that pioneered the catheter-ablation approach, reported by heart wire last year, arrhythmia-free survival rates after a single catheter-ablation procedure were relatively low at five years, just 29%, although the long-term success increased to 63% when outcomes were measured after the last ablation procedure. As a result, repeat ablation procedures were deemed likely necessary to achieve acceptable success rates.

"Why does this recurrence happen?" asked Reddy. "The reason is that during the ablation, in the locations that we ablate, we cause damage and isolation of the pulmonary veins. The lesions are close to each other, but not completely next to each other. You might get some edema and some transient block, but over time they reconnect."

Reddy said that late pulmonary vein reconnection is "ubiquitous with current approaches in most people's hands," with small electrophysiology studies performed postablation showing that as few as 20% of patients have complete pulmonary vein isolation. In other studies of patients required clinically to undergo a second procedure—a cohort that is likely to be at higher risk of recurrence, noted Reddy—just 4% of these higher-risk patients had complete isolation of the pulmonary veins. The new visually guided laser balloon is designed to improve the success rates following catheter ablation of atrial fibrillation by making it easier to achieve contiguous lesions, he said. As a result, operators would be able to successfully isolate the pulmonary vein, which is standard ablation procedure in patients with atrial fibrillation.

Endoscope and light source help make better lesions

With the new device, an endoscope as well as a light source is attached to the laser balloon, allowing clinicians to see the lesions created as they ablate in order to maintain contiguity. The new data presented at the HRS meeting include the first 200 patients treated with the new system, a combination of four clinical trials involving 16 sites and 33 operators. Of the 200 patients treated, average age 57 years, 187 failed a total of 309 antiarrhythmic medications.

Data from the trials showed that operators successfully isolated 99% of the pulmonary veins treated and that 80% of these veins were isolated with one sweep of the balloon catheter that created the encircling lesions. Reddy told heart wire that just one catheter is used in the procedure because the balloon attached is compliant, making it possible to treat small and large pulmonary veins. He noted that operators improved their efficiency with the system over time, with procedure, ablation, and fluoroscopy times decreasing after clinicians treated more than 15 patients.

Long-term follow-up is currently under way, with 107 of 200 patients having reached six-month follow-up. Reddy noted that 52 patients returned for pulmonary vein remapping at three months, and durable electrical isolation was observed in 86% of patients. There were pulmonary vein reconnections in 19 patients. Data stratified by operator experience showed that nearly 90% of pulmonary veins treated by experienced operators (>10 procedures) were persistently isolated, and 66% of patients treated by experienced operators had all pulmonary veins persistently isolated.

"These data are better than the literature shows, but we still have some work to do," said Reddy.

In the overall cohort, phrenic nerve injury occurred in five patients and cardiac tamponade in four patients. Reddy said these numbers are "extraordinarily good" given the investigational nature of the device and operators' relative inexperience with it. He expects these numbers to come down further, especially after future device redesigns. There were no reported cases of stroke, transient ischemic attack, pulmonary vein stenosis, or atrioesophageal fistula.

Reddy report receiving a research grant from CardioFocus. Disclosures for the coauthors are listed in the abstract.

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