The U. S. Food and Drug Administration approved Johnson & Johnson's Navistar Thermocool catheters to treat atrial fibrillation.

A dangerous heart defect, atrial fibrillation occurs when irregular electrical waves cause the upper chambers of the heart to contract irregularly, interfering with circulation and increasing the risk of deadly blood clots. This is the most frequently diagnosed form of arrhythmia, the medical term for an abnormal heartbeat.

In a news release the FDA said, till now, atrial fibrillation had been treated with blood thinning medication, and in certain severe cases, with open heart surgery, and these newly approved catheters are meant to be used when drug treatment hasn't succeeded.

"This approval provides physicians with another option for treating this common and potentially debilitating condition," said FDA's director for medical devices, Dr. Daniel Schultz.

According to the American Heart Association this condition affects over 2 million U. S. patients and accounts for 15 % of the strokes. The FDA said that there is no conclusive evidence that treatment with the catheter would reduce the patient's risk of stroke.

The Navistar ThermoCool saline irrigated radio-frequency ablation catheter and the EZ Steer ThermoCool Nav work by creating small scars using extreme heat which are strategically placed in heart tissue to block the nerve signals that cause irregular contractions. The device was earlier approved to treat atrial flutter which is a less severe type of heart problem.

The devices FDA approval was based on results of a study by J&J of 167 people at 19 medical centers in five countries. Results showed 62.7 % of patients treated with the catheter for one year had atrial symptoms eliminated as compared to 17 % people in the control group who were on traditional drug therapy.

Both the devices are made by California-based BioSense Webster, a Johnson & Johnson company.

The studies were conducted by Diamond Bar, Calif.-based BioSense Webster, a unit of Johnson & Johnson. Other medical device competitors including St. Paul-based St. Jude Medical are planning to market similar devices.