Participants in tests done as part of postmarketing surveillance (PMS) studies for carotid artery stenting to prevent strokes tend to be healthier than those who typically receive the devices, according to researchers. They found patients who had stents placed into their neck in these studies were healthier than other patients in a nationwide registry of people who received stents.
"Participants in PMS studies for carotid artery stenting have different clinical and procedural characteristics and lower mortality compared with nonparticipants," researchers conclude in their study, the results of which have been published in the journal Circulation. "Extrapolating results from PMS studies of carotid artery stenting to larger real-world settings should be done only with great caution."
The investigators compared the patients in the PMS study with those in the broader CARE Registry, a comprehensive national registry of patients undergoing both CAS and carotid endarterectomy. The voluntary registry includes more than 15,483 carotid revascularization procedures. All adult patients 18 years of age who undergo CAS or carotid endarterectomy at certain institutions are included in the registry with no other exclusions. The registry is funded by the American College of Cardiology Foundation without other external funding.
According to the researchers, patients participating in PMS studies differed from nonparticipants in a number of ways, especially in their neurological histories. Study participants had significantly lower rates of prior stroke (13.7 percent versus 19.2 percent), symptomatic target lesions (31.5 percent versus 58.2 percent) and acute evolving stroke (one percent versus 3.9 percent). In addition, PMS study participants had significantly higher rates of attempted and successful embolic protection device deployment.
"We were surprised," said Dr. Robert Yeh, the lead author of the study and a cardiologist at Massachusetts General Hospital and Harvard Medical School, as quoted by Reuters Health. "The intention and presumption of most post-marketing studies is that they represent the group of patients that we see in clinical practice."
However, Dr. William Gray, a cardiologist at Columbia University Medical Center and New York-Presbyterian Hospital, who has conducted post-market studies of stents, thinks there could be an explanation for the results. Gray said it comes down to insurance--especially Medicare, which pays for stenting when people have symptoms. When people don't have stroke symptoms, they are more likely to enroll in studies like post-marketing surveillance that will cover the costs of the procedure, Gray told Reuters Health.