The FDA approved the first ablation catheters for treatment of atrial fibrillation (uncoordinated contractions of the upper heart chambers), one of the most common types of arrhythmias (abnormal heart rhythms). Atrial fibrillation affects more than two million Americans.

The approved devices — the NaviStar ThermoCool saline irrigated radio-frequency ablation catheter and EZ Steer ThermoCool Nav — can be used to create small, strategically placed scars in heart tissue to block irregular electrical waves that cause atrial fibrillation. The FDA previously approved other ablation catheters to treat arrhythmias such as atrial flutter and ventricular tachyarrhythmia, but not atrial fibrillation.

The FDA based its approval on a clinical study of 167 patients at 19 medical centers in the United States, Brazil, Canada, the Czech Republic, and Italy. The devices were effective in eliminating symptomatic recurrence of atrial fibrillation episodes for one year in about 63% of treated patients vs. 17% of the patients in the control group.

As a condition of approval, manufacturer BioSense Webster, Diamond Bar, CA, (www.biosensewebster.com) must establish a physician training program and conduct post-market studies to collect data on the devices' long-term safety and effectiveness (including incidence of stroke, mortality, cardiac arrest, major bleeding, and pulmonary vein stenosis), and the effect physicians' experience has on safe operation of the device.