How Much Aspirin for Secondary Stroke and Primary CHD Prevention?

A neurologist prescribed a combination pill of dipyridamole(Drug information on dipyridamole) and aspirin(Drug information on aspirin) (2 tablets daily) for secondary stroke prevention in my patient, a 74-year-old woman. However, this patient also has increased cardiac risk. Isn't the amount of aspirin in this regimen (50 mg/d) subtherapeutic for coronary heart disease (CHD) prevention? Should I prescribe an additional 81 mg/d of aspirin?

----- Igor Dorokhine, MD
Bedford, Pa



Low-dose aspirin, 81 to 325 mg/d, is effective as secondary prevention for CHD. The Women's Health Study demonstrated that 50 mg of aspirin every other day is efficacious for primary stroke prevention in women of all ages and for CHD prevention in women older than 65 years.1

The combination of dipyridamole and low-dose aspirin has been shown in clinical trials to provide effective secondary prevention of stroke and transient ischemic attack (TIA); however, it has not been specifically tested for CHD prevention in a study similar to the Women's Health Study. Moreover, therapy with dipyridamole alone would theoretically increase the risk of coronary steal ischemia in patients being treated for secondary prevention of CHD. However, given what we know, this combination is a reasonable formulation for the prevention of CHD and recurrent stroke and TIA in women. Higher doses of aspirin would not be expected to offer greater efficacy and could result in greater bleeding risk. More research in women (and men) is needed.

----- C. Noel Bairey Merz, MD
Medical Director and Endowed Chair
Women's Health Program and Preventive Cardiac Center
Cedars-Sinai Medical Center
Los Angeles