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Antithrombotic agent withdrawal increases ischemic stroke risk

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – One in twenty ischemic strokes occurs within 60 days of withdrawal of antithrombotic agents, according to a report in the June 30th online issue of Stroke.

Antithrombotic medications may be withheld in anticipation of an invasive procedure and after bleeding complications to limit the risk of new or recurrent bleeding. “This is a very common decision in clinical practice,” Dr. Joseph P. Broderick told Reuters Health in an email. “Physicians must balance the risk of stroke and cardiovascular events with the risk of bleeding from a procedure if on antithrombotic medications.”

Dr. Broderick, from the University of Cincinnati College of Medicine, Ohio and colleagues used data from the Greater Cincinnati/Northern Kentucky Stroke Study to determine the number of acute ischemic strokes associated with withdrawal of antiplatelet or anticoagulant medications.

Of the 2197 strokes that occurred in 2090 adult patients during 2005, 114 (5.2%) occurred within 60 days of the withdrawal of antithrombotic medication.

In multivariable analyses controlling for various other risk factors for ischemic stroke, being on an antithrombotic medication at the time of the stroke was associated with significantly lower risk of 3-month mortality (odds ratio 0.55) and of 1-year mortality (OR 0.56) compared with discontinuation of such medication before stroke onset.

Almost half of the patients (54 patients) had their medication stopped by physicians for procedures, and over half of these patients’ strokes occurred within 7 days of medication withdrawal. Stroke events tended to cluster within the first 2 weeks after medications were stopped, especially in cases where medication was discontinued for procedures or because of supratherapeutic anticoagulation.

“The first step is for the primary treating physician to assess both the risk of stroke/cardiovascular events and the risk of bleeding with a proposed procedure,” Dr. Broderick explained. “The most important next step is excellent communication between the physician responsible for stroke/cardiovascular prevention, the physician performing the procedure, and the patient.”

“What is most challenging,” he continued, “is when the physician doing the procedure (epidural injection, eye operation, etc.) considers only the risk of bleeding related to their procedure (which in many types of procedures while on anti-platelet agents is small) and not the risk of stroke/cardiovascular events, which is not his/her immediate concern nor focus of care.”

The study found that only 5 of 38 patients undergoing the most common surgeries and procedures had bridging heparin therapy, according to the report.

“These same physicians also don’t manage the bridging of antithrombotic medications in higher risk patients,” Dr. Broderick continued. “Thus, it is critical that the primary treating physician who is trying to prevent cardiovascular events in a patient communicate carefully with the physician performing the procedure so the balance is maintained.”

“If the patient is managed by an anticoagulation clinic, this can provide continuity when bridging the patient,” Dr. Broderick added. “Time off an antithrombotic agent should be no longer than required. If bridging therapy is needed, it needs to be well coordinated with clear instructions to the patient and excellent follow-up post-procedure.”

Withdrawal of Antithrombotic Agents and Its Impact on Ischemic Stroke Occurrence
SOURCE:Stroke 2011.