Time of Anti-Clotting Therapy With Stents

Coronary stenting to open blocked arteries may require shorter term anti clotting therapy

(RxWiki News) Mesh tubes called stents can help keep blood vessels open in people with blocked arteries. To prevent blood clots from forming in stents, patients take anti-clotting agents, but it has not been clear how long this therapy should last.

For those who have atherosclerosis (a condition that blocks arteries), a procedure that involves placing a stent can help restore blood flow. To keep stents free from clots, patients often take dual antiplatelet therapy (DAPT) — usually aspirin and another medication.

While some studies have found that patients can benefit from DAPT for more than a year, new research suggests that prolonged DAPT may not provide any additional benefit.

"Ask a doctor about the risks of anti-clotting medications."

Gilles Montalescot, MD, a professor of cardiology at Centre Hospitalier Universitaire Pitié-Salpêtrière in Paris, France, led this investigation looking at the benefits and drawbacks of DAPT after one year in patients who had received stents. The study was called the ARCTIC-INTERRUPTION trial.

Stenting is part of a procedure called percutaneous coronary intervention (PCI) that opens blocked arteries in patients with atherosclerosis.

Also called angioplasty, the operation involves guiding a catheter through an artery to the blocked area. By inflating a balloon at the end of the catheter, the blood vessel reopens and returns blood flow to the heart. A stent keeps the artery propped open.

About 1 to 2 percent of people who have stented arteries develop a blood clot at the stent site, according to the National Heart, Lung, and Blood Institute. The clots can lead to stroke and heart attack, and the risk is greatest during the first few months after a stent is placed.

To prevent the clotting, some doctors recommend taking antiplatelet treatment, such as aspirin and another anti-clotting medicine for a year or more.

The downside is that too much DAPT can lead to severe bleeding complications.

Dr. Montalescot and his colleagues observed that PCI patients who do not have any heart episiodes one year after the procedure may not need any more DAPT.

The scientists followed 1,259 patients who had coronary stenting with drug-eluting stents (DES) and had no heart attack, stroke or other event after one year. At the one year mark, 624 patients had their DAPT discontinued and 635 continued to receive DAPT for an additional year.

After one year, the researchers reported that stent thrombosis (formation of a blood clot) or any urgent revascularization occurred in 1.3 percent of patients in the group that continued to get therapy, compared to 1.6 percent of those in the group that stopped getting antiplatelet treatment.

The researchers also compared primary endpoints in both groups. The primary endpoint was defined as the composite of death, heart attack, stent thrombosis, stroke or urgent revascularization after one year.

In the continuation group, 3.8 percent reached the primary endpoint, compared to 4.3 percent in the group that discontinued therapy.

For patients in the therapy continuation group, the rate of major bleeding events was 1.1 percent, compared to 0.2 percent in the interruption group.

“The ARCTIC-INTERRUPTION study suggests no ischemic [related to blood flow] benefit of DAPT continuation beyond one year after stenting in patients that do not experience an adverse event within the first year," said Dr. Montalescot in a press release.

In a related study, researchers also found that stent patients who received year-long anti-clotting therapy may not experience additional benefits compared to those who had the therapy for three months.

Led by Fausto Feres, MD, of the Instituto Dante Pazzanese de Cardiologia in São Paulo, Brazil, that related investigation followed 3,120 patients with drug-eluting stent implantation using an Endeavor zotarolimus-eluting stent.

Patients were randomly assigned to either receive three months or one year of DAPT. Current guidelines suggest long-term (12-month) DAPT after DES implantation.

After a year, Dr. Feres and his team measured Net Adverse Clinical and Cerebral Events (NACCE), including heart attack, stroke and death, in both groups. NACCE rates in the short-term DAPT group (6.1 percent) were similar to those who received the longer, standard DAPT (5.9 percent).

The long-term DAPT group showed a trend toward increased bleeding events.

“These promising findings could help shorten antiplatelet therapy time and reduce related complication risks for patients receiving select drug-eluting stents," said Dr. Feres in a press release.

These studies were presented on October 31 at the 25th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium, sponsored by the Cardiovascular Research Foundation (CRF).

Dr. Feres reported consulting fees/honoraria from Biosensors, Eli Lilly, and Medtronic. Dr. Montalescot reported research grants to the institution or consulting/lecture fees from Abbott Vascular, AstraZeneca, Bayer, Biotronik, Boehringer-Ingelheim, Eli Lilly and Company, GSK, Medtronic, Nanospheres, Novartis, Pfizer, Roche, Sanofi-Aventis, Stentys and WebMD among many other companies and organizations.

Review Date: 
November 5, 2013