Cardiac imagers who use CardioGen-82 generators face a potential crisis that is limiting their abilities to examine cardiac patients and maintain regular lab volumes, Howard C. Lewin, MD, of Cardiac Imaging Associates in Los Angeles, explained in an interview.
Since CardioGen-82 (Bracco Diagnostics) was reintroduced to the market in February, the FDA has required more stringent quality control. It appears that the heightened scrutiny has unearthed new concerns, but Lewin stressed that this time, “no patients are at risk, nor will they be exposed to excess radiation due to the new concern.”
Bracco sent a letter to the 106 sites that had reintroduced rubidium-82 CardioGen generators at the end of May. The letter warned customers of “the bump,” which is unpredicted breakthrough in strontium levels, well below the alert limit—meaning it is safe—but the bump is occurring early in the life of the generator.
“Breakthrough of strontium on a generator usually occurs as a result of time or total elution volume, but this breakthrough is happening early in the generator’s lifecycle,” said Lewin. “With this phenomenon, the breakthrough indication is going away after a few days, and then returns when we would expect to see the breakthrough, with more time and greater elution volume.”
Due to the stricter quality control process with CardioGen generators, and centralized data collection, it was noticed that this was occurring in the aggregate. In working with the FDA, Bracco discovered that the issue of the bump was connected to its generators, which used strontium from a single supplier.
“Since Bracco could not explain why the bump was occurring, the FDA recommended that the company stop using that supplier,” Lewin explained. “Unfortunately, that supplier was Bracco’s largest source of strontium—leading to an effective strontium shortage.”
Due to the lack of strontium, the CardioGen-82 generator cycles have been extended to seven weeks (as opposed to the four- to six-week cycles), which means all current 106 sites will face at least one week without service because the maximum life of a generator is 42 days.
More active labs will see more downtime, because the expiratory times for elution volume will be reached before the 42 days of use. For instance, Cardiac Imaging Associates will be without a generator for close to two weeks, due to the greater use of the generators.
The company has communicated to providers that the problem should be resolved by late August, according to Lewin, because the other strontium supplier will have produced enough to supplement the gap.
“At that time, we should at least be on a schedule that does not mandate downtime,” Lewin said. “Through these shortages, busy labs are struggling to manage patients and referring physicians.” Also, it requires the lab to educate its patients and referring physicians that this is not a safety concern. “It is definitely challenging,” he said.