Aug 16 (Reuters) - Patients implanted with certain heart defibrillators made by St. Jude Medical Inc should have X-rays or other imaging tests to check for abnormalities, the U.S. Food and Drug Administration said on Thursday.
The agency also called for surveillance studies of the company's implantable defibrillators with its newer "Durata" lead, sending shares of St. Jude down more than 4 percent.
The lead is a wire attached to the device that is inserted into the heart to detect abnormal heart rhythms and deliver an electrical shock to restore normal heartbeat.
The X-ray recommendations apply to products with "Riata" leads, which were recalled by St. Jude in November 2011 after reports of premature erosion of the insulation around the conductor wires, also called insulation failure.
The company stopped selling the Riata leads in late 2010, but around 79,000 remain implanted in patients in the United States.
St. Jude said in June that an internal investigation showed that damage to one of its Durata defibrillator lead wires was not caused by the same type of abrasion which forced the recall of its Riata products.
The FDA also said it is requiring post-market surveillance studies on St Jude's recalled QuickFlex and QuickSite CRT leads. CRT devices are small, battery-powered units implanted in the chest of heart failure patients.
Insulation failure may cause some of the electrical conductors inside Riata leads to move within or move entirely outside the outer lead insulation. The lead can malfunction, causing potentially life-threatening abnormal heart rhythms.
Shares of St. Jude fell 4.4 percent to close at $36.87 on the New York Stock Exchange.