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New RF catheter for pulmonary vein isolation linked to silent embolism risk

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Among patients with atrial fibrillation undergoing pulmonary vein isolation, the use of a multielectrode phased RF ablation catheter designed for the purpose appears to generate more asymptomatic intracranial embolic events than either a conventional irrigated RF ablation catheter or a cryoballoon catheter, according to a European study.

“Further studies to clarify the origin of these embolic lesions are mandatory to reduce the rate of silent embolisms during ablation procedures in the left atrium,” the researchers advise in their report in the July 5th issue of the Journal of the American College of Cardiology.

Dr. Claudia Herrera Siklody, with Herz-Zentrum in Bad Krozingen, Germany, and colleagues note that pulmonary vein isolation when performed with conventional radiofrequency (RF) externally irrigated ablation catheters is technically demanding, and new devices have been introduced aimed at making the procedure faster and easier.

Two such devices — the cryoballoon and the multielectrode phased RF ablation catheter — have been approved for clinical use in Europe, but safety data on them are scarce, the authors continue. To compare the safety of these devices in terms of the incidence of subclinical intracranial embolic events, they conducted a study in 74 patients with symptomatic atrial fibrillation referred for pulmonary vein isolation.

Ablation was performed with an externally irrigated RF quadripolar catheter or a double-coated over-the wire cryoballoon or a phased decapolar circular mapping and ablation catheter used in conjunction with a multichannel RF generator.

Cranial MRI before and after pulmonary vein isolation was used to detected new intracranial embolic lesions, according to the report.

Neurologic exams were normal before and after the procedure in all the patients, but a new embolic lesion was seen in 2 patients (7.4%) in the conventional RF group, 1 patient (4.3%) in the cryoablation group, and 9 patients (37.5%) in the multielectrode RF group.

In discussing the results, the authors suggest that lack of irrigation may be one reason for the high incidence of asymptomatic embolic with the multielectrode catheter. Another possibility is that, while phasing during energy delivery is supposed to allow tissue cooling, overheating of some electrodes in certain positions may lead to charring and generation of emboli.

Dr. Herrera Siklody and colleagues conclude that further study of the causes and significance of these emboli is required to determine the safety of the device.

J Am Coll Cardiol 2011;58.