More study of heart imaging agent risks urged

By Susan Heavey

SILVER SPRING, Maryland (Reuters) - Makers of contrast agents used to enhance echocardiogram images need to conduct larger studies to better evaluate the heart risks seen in some patients, a U.S. panel of medical experts said on Tuesday.

The Food and Drug Administration imposed warnings late last year on imaging agents made by General Electric Co's GE Healthcare and Lantheus Medical Imaging after receiving 200 reports of complications, including seven deaths.

But the agency relaxed the restrictions earlier this year, to allow somewhat wider use, after doctors said the agents gave them life-saving information.

Echocardiograms help diagnose heart disease and other conditions by using ultrasound to show moving pictures of the heart. Contrast agents such as GE's Optison and Lantheus's Definity make the images clearer in some cases.

"It's not that a drug or a test agent is without risk. It's that I need to understand the risk," said William Hiatt, a medical professor at the University of Colorado in Denver who chaired the panel.

FDA's director of medical imaging products, Dwaine Rieves, told the panel that the agency wanted advice on what safety issues to consider as companies seek to use imaging agents to diagnose other conditions such as liver problems.

Ideally, the panel of experts said, companies either already selling or seeking to market such agents would launch a randomized placebo-controlled study of thousands of patients, but they could also conduct less-involved observational studies.

GE Healthcare and Lantheus have already agreed to review post-marketing data for safety issues, but Rieves told reporters after the meeting that the panel's recommendations could affect the advice given to companies seeking future FDA approvals.

Representatives for GE Healthcare and Lantheus as well as Bracco Diagnostic Inc, which sells its SonoVue contrast agent in Europe, told panelists the agents are safe and noted that many patients given the agents are already very sick.

"There were no safety concerns ... in the safety studies we investigated," said Steven Feinstein, a medical professor at Rush University Medical Center in Chicago, who spoke on behalf of GE Healthcare. The company returned Optison to the U.S. market in late 2007, two years after manufacturing woes brought it off the market.

Various physicians speaking to the panel urged further study but said medical information gleaned with contrast agents outweighed their side effects.

"The black box warning has had a significant deterrent effect," said William Zoghbi, president of the American Society of Echocardiography, which estimates about 22 million heart ultrasounds were conducted in the United States in 2005.

He urged the companies and the FDA to collect more data to better determine which patients are at risk and eliminate the warnings.

(Editing by Tim Dobbyn)