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Dipyridamole Plus Aspirin Helps Prevent Stroke Recurrence

Combining aspirin with dipyridamole may offer stroke survivors better protection than aspirin alone against a second stroke, according to a new study.

The study, conducted by head researcher Dr Ale Algra and The ESPRIT* Study Group, was published in the May 20 issue of The Lancet and reported by on May 18.

Both dipyridamole and aspirin have anti-clotting effects. They prevent blood platelet cells from sticking together or to prosthetic heart valve surfaces. The drug combination is available in the US under brand-name Aggrenox.

The current guidelines for preventing a second stroke recommend taking either aspirin alone; combined aspirin and dipyridamole; or clopidogrel (Plavix, also an anti-clotting drug), depending on the individual patient profile.

Study Results

"The results of ESPIRIT, combined with the results of previous trials, provide sufficient evidence to prefer the combination therapy of aspirin and dipyridamole over aspirin " for stroke survivors, wrote lead author Dr Algra in The Lancet.

The randomized, controlled study examined the effects of aspirin (30-325 mg daily) with or without dipyridamole (200 mg twice daily) within 6 months of a transient ischemic attack (TIA) or minor stroke. Researchers followed the participants for an average of 3.5 years.

Results showed that 13% of the 1,363 participants who received combination therapy experienced circulatory events (such as second strokes), compared with 16% of the 1,376 participants who received only aspirin.

Implications for Treatment

The risk-reduction the study showed is "a modest difference but a significant difference," according to Dr Cathy Sila, associate director of the cerebrovascular program at the Cleveland Clinic, said "We're always looking for something that eats away at the problem more."

Dr Sila pointed out that another finding of the study has treatment implications for stroke victims: the fact that that the benefit of combination therapy became apparent only after about 2.5 years of treatment.

She also noted that, while the study supports current US guidelines for preventing stroke recurrence, "I don't think [combined therapy] is going to replace aspirin" for all people who have had strokes or mini-strokes (TIAs).

For one thing, the source of the clot must be considered: If the cause of the clot was atrial fibrillation (abnormal heartbeat that promotes clot formation), warfarin would be the preferred treatment. Moreover, if the clot did not originate in the heart, the patient's reaction to dipyrimadole must be considered - about one third of participants receiving combination therapy stopped taking it because of side effects (most notably, headaches).

Yet another issue is cost. Dr Sila calculated that one month's supply of Aggrenox would be $122, and for Plavix $117. In contrast, one month's use of aspirin would cost less than $2.

The results of the ESPRIT study are not definitive, said Dr Sila. Studies on secondary stroke prevention continue, including one that compares Aggrenox with Plavix.

However, "the vast majority" of people who have had strokes should be taking clot-preventing medication of some type, said Dr Sila. "It's up to the physician to figure out a way to make these treatments realistic, so we can achieve the benefits of medication."

The study was funded by a variety of European government health agencies, as well as the Council of Singapore.

*ESPRIT = European/Australasian Stroke Prevention in Reversible Ischemia Trial.

Sources:- Adding Drug to Aspirin May Better Prevent Second Stroke,, May 18, 2006.- Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT): randomised controlled trial. The ESPRIT Study Group, The Lancet, volume 367, pages 1665-1673, May 20, 2006.

Posted: May 2006