Many of the high-risk implantable cardiac devices in use today were approved through a supplement pathway that does not require new clinical data on the safety and effectiveness of changes made to the products since their original approval, a review of an agency database showed.

From 1979 through 2012, 77 original pre-market approval (PMA) applications -- which required the manufacturers to provide clinical data on the safety and effectiveness of the devices -- were cleared by the FDA, according to Aaron Kesselheim, MD, JD, MPH, of Brigham and Women's Hospital in Boston, and colleagues.

During that same time, however, those original PMAs were subject to 5,829 approved supplement applications, which covered everything from relatively minor changes to labeling, materials, or packaging to substantial design changes, often without the need for additional clinical data, they reported in the Jan. 22/29 issue of the Journal of the American Medical Association.

"It behooves physicians and patients when they're considering a device to understand not only that the device has been FDA approved but to understand the process through which the device was FDA approved and any data that exist about the device," Kesselheim said in an interview.

The FDA uses the PMA process to evaluate new high-risk medical devices, which include pacemakers, implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. But changes to previously approved devices can be introduced using the supplements.

"The benefits [of the supplement pathway] are the more rapid approval and clinical use of new technology," commented Michael Rinaldi, MD, director of clinical research at Carolinas HealthCare System's Sanger Heart & Vascular Institute in Charlotte, N.C., who was not involved in the study. "Requiring a large randomized trial for every proposed iterative device improvement would slow and potentially stop needed improvements in technology."

But it also means that many of the devices clinicians are implanting into patients currently -- which may be substantially different from the device included in the original PMA after numerous small changes -- have not been subject to rigorous clinical testing.

Kesselheim and colleagues noted that the Medtronic Sprint Fidelis and St. Jude Medical Riata ICD leads -- which were recalled in 2007 and 2011, respectively -- were both approved through the supplemental process and were never tested in clinical studies before entering the market.

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