The U.S. Food and Drug Administration may have to reconsider a warning it issued in 2008 that CT imaging tests could interfere with internal electronic devices, according to a recently published study in the Journal of the American College of Cardiology.
According to the warning, issued nearly six years ago, a small number of patients had reported that CT scans had interfered with devices like pacemakers, defibrillators, neurostimulators and implanted or externally worn drug infusion pumps. Now, however, researchers led by Timm Dickfeld of the University of Maryland, Baltimore, say they have found no such evidence after reviewing 10 years worth of CT scans at their hospitals.
The researchers looked at 515 scans that involved direct radiation exposure of defibrillators and pacemakers at two large-volume centers. They found that none of the CT exams were associated with instances of death, bradycardia, or tachycardia requiring termination of the scan or an immediate intervention, unplanned hospital admissions, reprogramming of the device, inappropriate defibrillator shocks or device replacement believed to be due to the CT imaging.
The FDA has since updated its advisory, but it still mentions the possibility of reprogramming and inappropriate shocks from CT scans. Dickfeld, in a recent Heartwire article, says that while the FDA had "softened" the wording of the advisory, he hopes that the study "can close the loop a bit and provide some assurance to physicians and also to patients. We don't know what the effect was of this advisory, but we do know from our own colleagues that there was a significant amount of uncertainty."
In an accompanying editorial in JACC, Elena Arbelo, M.D., and Joseph Brugada, M.D., say the FDA may have been "reckless" in issuing the advisory and deterring patients from undergoing scans that could have detected problems whose seriousness outweighed the unproven, potential risks to their devices.