CardioFocus Inc. of Marlborough, Mass., developer of the HeartLight endoscopic ablation system for treatment of atrial defibrillation, has announced that a patient was treated with the visually guided device in a US clinical trial. The system incorporates an endoscope for direct visualization of a beating heart, in real time and without radiation. It uses laser energy for efficient and precise ablation. The trial will randomize HeartLight against the NaviStar Thermocool catheter. Only a single ablation procedure with HeartLight will be permitted, while repeat ablation may be performed with Thermocool. The trial will randomize about 350 patients at up to 25 US centers.