Guidant Corp. (GDT) Friday said the Food and Drug Administration (search) has classified the recall of some of its recently recalled implantable heart devices as Class I, its highest priority.

The products include Ventak Prizm 2 DR (search), manufactured on or before April 16, 2002, and Contak Renewal 1 (search) and 2 devices, manufactured on or before Aug. 26, 2004.

Letters to physicians and patients were sent out on June 17, 2005. The company advised doctors to stop using some of the heart devices last month after issuing a recall.

The FDA assigns a recall Class I status when there is "a reasonable probability that, if a particular device is malfunctioning, the malfunctioning device will cause serious adverse health consequences or death."

FDA has designated as Class II the recalls of Ventak Prizm AVT, Vitality AVT, and Renewal AVT devices, Renewal 3 and 4, Renewal 3 and 4 AVT, and Renewal RF devices. The lower classification indicates that the product "may cause temporary or medically reversible adverse health consequences, but that the probability of serious adverse health consequences is remote."

The FDA said the recall class designations do not affect the company's recommendation to physicians that they continue normal follow-up visits at three-month intervals.

Neither Guidant nor the FDA is making a recommendation as to whether individual patients should have their devices removed.

Implantable cardioverter defibrillators (search), or ICDs, monitor the heartbeat and deliver a life-saving shock when they detect an irregular rhythm.

"These are very complex clinical decisions that need to be made based on the device and the condition of the patient," Dr. Daniel Schultz, director of FDA Center for Devices and Radiological Health, told reporters on a conference call. "We believe it is vitally important for the specific decision ... to remain in the hands of the doctor and the patient."

The FDA continues to evaluate the circumstances of the timing and notification of the recalled devices. It is likely the investigation will conclude in a matter of weeks, the agency said.

Shares of Guidant, which agreed to be acquired by Johnson & Johnson for $25.4 billion, recouped earlier losses and were off 21 cents to $67.09, well off the day's worst levels at $64.20 on the New York Stock Exchange (search).