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Physicians should examine the risk factors—for example, whether the patient is likely to experience a stroke—before giving patients undergoing interventional heart procedures a combination of anti-blood clotting therapies, according to a study from Jefferson Medical College.

In the study, to be published in the May issue of Pharmacotherapy, Thomas Jefferson University heart researchers reviewed the results of patients who had an interventional heart procedure--such as angioplasty or coronary artery stenting--at Thomas Jefferson University Hospital. Patients undergoing these procedures usually require various types of blood thinners such as aspirin and clopidogrel (Plavix) but some also require warfarin, a potent blood thinner.

The study was designed to assess the safety profile of using all three of these agents, and to identify patient characteristics that increase the risk of hemorrhage in this setting.

The combination of aspirin and clopidogrel (known as dual-antiplatelet therapy) is routinely prescribed to prevent clotting within the stent in patients who have these devices inserted into their coronary arteries.   

Warfarin is a commonly prescribed “blood thinner” for people who have an artificial heart valve, deep vein thrombosis, pulmonary embolism or a heartbeat irregularity known as atrial fibrillation which is known to foster the development of clots in the heart.

The researchers led by Deborah DeEugenio., PharmD, BCPS, CACP, clinical pharmacist at the Jefferson Heart Institute at Thomas Jefferson University, looked retrospectively at 97 patients, considered the active group, who underwent coronary stent placement or brachytherapy at Jefferson University Hospital from January 1, 2000 to

September 30, 2005. A control group, who matched the active patients by procedure type, year and sex, were also studied. All controls were discharged on aspirin and clopidogrel.

To determine the safety of the three-drug combination, the researchers looked at the timing of the first major bleed, after the heart procedure. They defined a major bleed as fatal bleeding, bleeding at a critical site, bleeding requiring intervention and more.

They found that there were 14 major bleeds in the active group and three in the control group. All major bleeds in the control group occurred within days of the procedure, while major bleeding in the active group occurred throughout the 182-day study period.

According to the researchers, the study shows that warfarin administration significantly increases the risk of major bleeding following an interventional heart procedure in patients receiving the dual-antiplatelet therapy.

As a result, they offer two recommendations:

• In patients with low risk for a thromboembolic event, such as a stroke, consider stopping the warfarin until the dual-antiplatelet therapy is no longer required.
• Conduct larger, prospective studies to further characterize safety and bleeding risk and to determine appropriate antithrombotic therapy following interventional heart patient requiring chronic warfarin therapy.