Benefits of Ultrasound Contrast Agents Supersede Potential Risk to Heart Patients

A cardiologist called upon U.S. officials to reconsider a strong warning they recently placed on a diagnostic imaging modality, stating that the warning could prevent clinicians from detecting life-threatening cardiac events.

In October 2007, the U.S. Food and Drug Administration (FDA; Rockville, MD, USA) placed a black box warning on ultrasound contrast agents, which are used to improve the quality of echocardiography images in patients who do not otherwise have optimal images, after receiving reports of four deaths and serious reactions shortly after or during the infusion.

A black box warning is given to drugs that carry a considerable risk of serious or even life-threatening adverse effects. The warning placed on ultrasound contrast agents was issued without a formal examination of the risks and benefits of using them, reported Melda Dolan, M.D., associate professor of cardiology at Saint Louis University School of Medicine (MO, USA). Dr. Dolan's research demonstrated that the contrast agents are indeed safe, and withholding their use, which has occurred since the FDA warning, would make diagnosis of life-threatening heart disease more difficult.

"Based on the results of our study, we believe the FDA should reconsider its stance on contrast agents because the benefits outweigh the potential, although not established, risk,” stated Dr. Dolan, who was the lead investigator of the study. Dr. Dolan presented the research findings on March 31, 2008, at the 57th annual American College of Cardiology Scientific Session in Chicago, IL, USA.

In 1997, after significant scrutiny, the FDA approved the use of ultrasound contrast agents, which are gas-filled microbubbles that are administered intravenously into the blood, for these cases. The use of contrast agents to get optimal images is necessary in approximately one out of five individuals, according to Arthur Labovitz, M.D., director of the division of cardiology at Saint Louis University and a contributing researcher to the project.

The goal of this study was to assess the overall risk and benefits of ultrasound contrast agents. Utilizing findings from two university hospitals, the researchers examined the clinical outcomes of nearly 24,000 patients who received contrast agents during an echocardiogram and compared their results to those from a group of about 6000 patients who did not need to receive contrast agents.

To test the safety of contrast agents, the researchers looked at the short-term (within 30 minutes of the infusion) and long-term (within 24 hours) outcomes and noted any serious adverse events or deaths. Of the nearly 24,000 individuals to receive the contrast agents, not one experienced an adverse event within 30 minutes. One death and three non-fatal heart attacks occurred within 24 hours; however, these could not be attributed to the contrast agents.

To evaluate the effectiveness of ultrasound contrast agents, the researchers compared echocardiogram images, which were enhanced by contrast agents, with images of patients who did not need contrast agents. They found the images of both equally clear. The researchers evaluated the long-term survival rate of patients who received contrast agents during pharmaceutical stress echocardiogram exams and those who did not. They found nearly identical rates of death between both groups.


Related Links:
Food and Drug Administration
Saint Louis University School of Medicine