Countering long-standing assumptions and best practices, stents—small mesh cages used to prop open blocked arteries to treat heart attacks and chest pain—are largely useless in addressing patients' pain, according a study published Thursday in the Lancet.
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According to the New York Times, providers generally insert stents to open arteries among patients who have experienced heart attacks, which affects roughly 790,000 Americans every year.
However, the devices are most frequently inserted to ease chest pain among patients who have clogged arteries. According to current U.S. guidelines, stenting is an appropriate procedure for individuals who have a blocked artery and chest pain and who have undergone "optimal" medication therapy to address the condition.
Overall, more than 500,000 patients receive stents worldwide each year, the Times reports.
For the study, Justin Davies, a cardiologist at Imperial College London, and colleagues recruited 200 study participants eligible for stenting. All the patients had a profoundly blocked coronary artery and chest pain severe enough to restrict their physical movement.
The study participants all received a six-week treatment of medications designed to lower their heart attack risk, such as aspirin, a statin, and medication for blood pressure. They also received drugs to ease chest pain by widening blood vessels or slowing down the heart.
Following the medication regimen, all of the study participants had a sham or real stenting procedure. Patients in both groups had a catheter inserted in the groin or wrist that stretched up through the blocked artery, at which point they either received the stent or the surgeon simply withdrew the catheter. All the patients received medication to prevent blood clots following the procedure.
The study is one of the few cardiology studies to garner regulatory approval that compares outcomes among patients who received sham versus real procedures—in fact, according to the Star Tribune, it is the first to assess the placebo effects of a stent procedure. The study was double-blind, with neither the patients nor the researchers assessing them, informed as to who had undergone the actual procedure.
The researchers found that the stents greatly improved blood flow in the previously blocked artery among patients who received the devices. However, when the researchers checked patients' chest pain levels six weeks after their procedures, there was no difference between the two groups: Both groups reported less pain and performed better on treadmill tests.
According to the Times, cardiologists hypothesized that the groups may have reported similar outcomes for chest pain because atherosclerosis affects multiple blood vessels. As a result, addressing only the largest blockage with a stent might not relieve a patient's overall discomfort. In addition, the cardiologists hypothesized patients who received the sham procedure might have experienced a placebo effect.
In an editorial accompanying the study, David Brown of Washington University School of Medicine and Rita Redberg of the University of California-San Francisco recommended that based on the study, "all cardiology guidelines … be revised." Noting that stent insertion carries risks—including possible death—Redberg said the procedure should only be used for heart attack patients.
Separately, Brahmajee Nallamothu, an interventional cardiologist at the University of Michigan, said the findings are "very humbling … for someone who puts in stents." And William Boden, a cardiologist and professor of medicine at Boston University School of Medicine, called the study's findings "unbelievable."
However, despite the findings, experts acknowledged that many providers will continue offering stents for chest pain as some might be reluctant to base treatment on findings from a single study, the Times reports. For instance, David Maron, a cardiologist at Stanford University, said while the study was "very well conducted," it focused on patients with just one profound blockage and had a relatively limited timeframe. "We don't know if the conclusions apply to people with more severe disease," he said. "And we don't know if the conclusions apply for a longer period of observation."
Lead study author Davies also said he was reluctant to swear off stenting as treatment for eligible patients with chest pain, noting that some patients either are not willing or are not able to take the appropriate medication.
While the study alone may not result in a change in care, some experts say the findings could help ease approval for other studies involving sham procedures—a move that ethics boards in U.S. hospitals frequently resist, according to Boden, because providing sham care "flies in the face of guidelines."
Citing the potential for further studies involving sham procedures and placebo assessment, Neal Dickert—a cardiologist and ethicist at Emory University—said, "This may turn out to be an important moment" (Kolata, New York Times, 11/2; Carlson/Olson, Star Tribune, 11/2).
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