About one in six patients who undergo balloon angioplasty to open a clogged artery and who have a stent implanted to keep it open do not fill prescriptions for blood thinners immediately, and their failure to do so doubles their risk of having a subsequent heart attack or dying, researchers said Tuesday. The average delay was about three days, but even a single day's delay in obtaining the crucial drugs increases the risk, according to the report in the journal Circulation: Cardiovascular Quality and Outcomes.
The delay in obtaining the drugs was the greatest among patients who needed them the most, the elderly and those who had previously had heart attacks, said Dr. P. Michael Ho of the Denver VA Medical Center and the University of Colorado, Denver, the lead author of the paper. And the study involved only patients in a large integrated healthcare system where people had ready access to drugs, so the findings may represent an underestimate of the risk, he said.
Stents are wire mesh tubes that are inserted into an artery after a balloon is used to squash obstructions flat. They are designed to keep the arteries open, but like all foreign objects, they have a tendency to trigger clot formation themselves. Blood thinners are thus crucial to prevent clots from forming. A slight delay in taking the blood thinners can allow a tiny bit of coagulation that can later grow into a significant clot.
Ho and his colleagues studied 7,402 patients who underwent angioplasies with stent implantation between 2004 and 2007. All were able to get prescription drugs at reduced costs through their health plans. The patients were all prescribed clopidogrel (brand name Plavix), which was the only blood thinner in common use then. The researchers found that 16.3% of the patients (1,210) waited at least a day to fill their clopidogrel prescription--the median was three days--and 2.2% (165) never filled them at all. Those who delayed filling their prescriptions also were more likely to delay obtaining refills, suggesting that their adherence was not very good.
In the 22 months average after their surgeries, 7.9% of those who filled their prescriptions on the day of discharge from the hospital had another heart attack or died, compared to 14.2% of those who delayed filling them. Ho speculated that many of the patients may be prescribed multiple medications and may not realize the importance of the clopidogrel.
Some experts have recommended that hospital revive the old practice of sending patients home with a few days' supply of their drugs to allow them time to procure more.
-- Thomas H. Maugh II
Failure to immediately fill a prescripton for Plavix after having a stent inserted doubles a patient's risk of heart attack or death. credit: AP Photo / Mark Lennihan