"An alarming one in seven patients in our study stopped taking their antiplatelet medication within the first 30 days of receiving a drug-eluting stent (DES), even though they were prescribed the drugs at the time of hospital discharge and recommendations are to continue them for a minimum of three to six months after the procedure," said John A. Spertus, M.D., M.P.H., lead author of the study and director of cardiovascular education and outcomes research at the Mid America Heart Institute in Kansas City, Mo.
Researchers looked at the real-world use of DES in heart attack patients and a class of drugs called thienopyridines that work along with aspirin to help keep platelets in the blood from clumping and leading to the formation of blood clots. Thienopyridines include the drugs clopidogrel and ticlopidine. Blood clots can obstruct a coronary artery, causing a heart attack.
Several studies have confirmed the benefits of DES in preventing restenosis (reclosing of the artery that had been treated). However, with stents there is the potential problem of stent thrombosis (blood clots forming inside the stent), which can be associated with devastating consequences. Antiplatelet agents, including thienopyridines, reduce the likelihood of stent thrombosis. According to Spertus, no previous studies have defined the frequency and consequences of prematurely discontinuing thienopyridine therapy.
The risk of stent thrombosis with bare-metal stents (stents not coated with a drug) decreases rapidly after two to four weeks, and patients typically need thienopyridines for only about one month. In comparison, with drug-eluting stents the risk of stent thrombosis lasts for a longer period of time and patients with DES require prolonged thienopyridine therapy (typically for several months).
In a 19-center study of 500 heart attack patients (average age 61 years and 68 percent male) who received a DES and were discharged with prescriptions for thienopyridines, 68 patients (13.6 percent) stopped their medication within 30 days. Those who stopped were:
After one year, 7.5 percent of patients who stopped their medication within the first 30 days had died compared to 0.7 percent of the compliant patients. In addition, 23 percent of those who stopped their medication early were readmitted to the hospital, compared to 14 percent of those who continued their medication, he said.
"The rate of death was significantly higher and the frequency of cardiac hospitalizations was almost twice as great over the next 11 months among those who stopped their thienopyridines as compared to those who continued them," Spertus said.
Researchers said previous studies under controlled conditions found that the combination of DES plus three to six months of antiplatelet medication effectively prevented restenosis for patients with atherosclerosis.
Yet, clinical trials differ from real-world practice where patients may have less intense follow-up or limited access to the medications they need. That's why it was important to see how patients would fare under real-world conditions, including those getting stents on a more emergency basis, such as for treatment of heart attack, Spertus said.
"The lack of a high school education was associated with a 79 percent higher risk of stopping treatment," Spertus said. "This finding indicates that more patient education about why the medicine is necessary could save lives.
Treatment decisions made at the height of clinical urgency can have long-lasting consequences on the chronic care that patients need to have the best possible outcomes. In this case, prolonged use of thienopyridines after DES implantation for heart attack treatment is clearly required for patients to get all the benefits of reduced restenosis and to avoid the catastrophic complication of stent clotting, he said.
Co-authors are Richard Kettelkamp, D.O.; Clifton Vance, M.D.; Carole Decker, R.N., Ph.D.; Philip G. Jones, M.S.; John Rumsfeld, M.D., Ph.D.; John C. Messenger, M.D.; Sanjaya Khanal, M.D.; Eric Peterson, M.D., M.P.H.; Richard G. Bach, M.D.; Harlan M. Krumholz, M.D., S.M. and David J. Cohen, M.D., M.Sc.
The research was funded in part by CV Therapeutics, Palo Alto, CA.
Statements and conclusions of study authors published in the American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.
NR06 1063 (Circ/Spertus)
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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