Aspirin Effective, Resistance is Rare

Aspirin resistance at all doses — 81 mg, 162 mg and 325 mg — is rare, less than 5 percent, in patients with heart disease, says a U.S. study.

Researchers at the Center for Thrombosis Research at Sinai Hospital of Baltimore studied 125 patients with a history of coronary artery disease treated with aspirin. All patients were randomly placed on 81 mg, 162 mg and 325 mg of aspirin daily for four weeks each, for a total of 12 weeks.

When measuring the ability of aspirin to block its target, COX-1, it was found highly effective at all dose levels, according to the study published in the journal Circulation.

Most coronary artery disease deaths are caused by platelets sticking together and forming blood clots that block blood flow within arteries, resulting in a heart attack. By inhibiting clotting, aspirin keeps platelets from sticking together by specifically blocking an important enzyme, COX-1.

The occurrence of clotting in patients taking aspirin therapy has been attributed to the failure of aspirin blocking its target and is a hot topic in cardiovascular disease today, lead investigator Dr. Paul Gurbel, of Sinai Hospital, said in a statement. However, our data suggest that aspirin blocks COX-1 with high efficiency.