Stress Test Chemicals May Increase Risk of Heart Attacks, Death: FDA

Two chemicals that are used to conduct cardiovascular stress tests may actually increase the risk of individuals suffering a heart attack or sudden death, according to a warning issued by federal health regulators.

In a safety announcement issued on Wednesday, the FDA warned doctors about the risk of rare, but serious side effects associated with Lexiscan and Adenoscan, two products sold by Astellas Pharma US, Inc. for cardiac nuclear stress tests among individuals who cannot exercise.

Multiple adverse event reports have been received by the FDA, including dozens of heart attacks and deaths following use of Lexiscan and Adenoscan during stress tests.

The FDA has approved new warnings for the drugs, indicating that Lexiscan and Andenoscan should be avoided among patients who have signs of unstable angina or cardiovascular instability.

The chemicals are designed to stimulate the cardiovascular system to place increased stress on the heart. This allows doctors to take images of the blood flow to and from the heart muscle. During the procedure, the chemicals dilate the arteries in the heart and increase blood flow. This reveals which arteries are flowing freely and which arteries are struggling with blockages.

While doctors often use these cardiac stress tests to diagnose other ailments, the FDA highlights the importance of warning about the possible risk of heart attack and death that may be caused by the stress tests. The agency indicates that cardiac resuscitation equipment and trained staff should be available before administering the drugs.

Spurred by an investigation into adverse events connected to the drugs, the FDA reviewed events between June 24, 2008, and April 10, 2013. Lexiscan was linked to at least 26 heart attacks and 29 deaths among individuals who received the drug. Adenoscan was found to be associated with six heart attacks and 27 deaths from May 18, 1995, to April 10, 2013. All patients experienced the adverse effects within six hours of taking the drugs.

Based on the data available, the federal drug regulators indicated that they were unable to determine if there is a difference in the risk of heart attack or death between Lexiscan and Adenoscan.

Astellas responded to the FDA statement by indicating that the company takes safety warnings seriously. The drug maker also emphasized that it continues to work in cooperation with the FDA to ensure all healthcare professionals are aware of the updated safety information.