Aspirin doesn't help in preventing second stroke in 20 percent of the cases, say researchers. The study of sciences found that up to 20 percent of patients taking aspirin to lower the risk of suffering a second cerebrovascular event do not have an antiplatelet response from aspirin, the effect thought to produce the protective effect, Forbes TV reported.
Millions of people use low dose aspirin either for prevention of a second stroke, second heart attack or second episode of peripheral artery disease, they said. In those three indications, it's crystal clear that aspirin reduces the risk of a second heart attack or stroke in most patients. But we have known for years that in some stroke and heart attack patients, aspirin has no preventive effect, they added.
With no definitive data on the frequency of this condition, known as aspirin resistance, physicians were left with a best guess of between 5 and 50 percent. The researchers have now confirmed the 20 percent figure through a strictly controlled study conducted over 29 months in 653 consecutive stroke patients.
Aspirin reduces the risk of a cardiovascular event by preventing blood platelets from aggregating in the arteries and obstructing blood flow. If blood drawn from a patient taking aspirin shows that platelets are still aggregating, that patient is diagnosed as being aspirin resistant. If a stroke patient has a second stroke while on aspirin.