The cardiac nuclear stress test agents Lexiscan, or regadenoson, and Adenoscan, or adenosine, are FDA approved for use during cardiac stress tests in patients who cannot exercise adequately. Lexiscan and Adenoscan help identify coronary artery disease. They do this by dilating the arteries of the heart and increasing blood flow to help identify blocks or obstructions in the heart's arteries, FDA officials said.
Lexiscan and Adenoscan cause blood to flow preferentially to the healthier, unblocked or unobstructed arteries, which can reduce blood flow in the obstructed artery. However, in some cases, this reduced blood flow can lead to a heart attack, which can be fatal, the FDA said.
"We have approved changes to the drug labels to reflect these serious events and updated our recommendations for use of these agents," FDA officials said in a statement.
"Healthcare professionals should avoid using these drugs in patients with signs or symptoms of unstable angina or cardiovascular instability, as these patients may be at greater risk for serious cardiovascular adverse reactions."
The Warnings & Precautions section of the Lexiscan and Adenoscan labels previously contained information about the possible risk of heart attack and death with use of these drugs.
"However, recent reports of serious adverse events in the FDA Adverse Event Reporting System database and the medical literature prompted us to approve changes to the drug labels to include updated recommendations for use," the FDA said.
"Some events occurred in patients with signs or symptoms of acute myocardial ischemia, such as unstable angina or cardiovascular instability. Cardiac resuscitation equipment and trained staff should be available before administering Lexiscan or Adenoscan. At this time, data limitations prevent us from determining if there is a difference in risk of heart attack or death between Lexiscan and Adenoscan."