Despite a flood of drugs on the market, aspirin remains the best simple treatment for preventing heart disease, according to the latest medical studies in the United States. Doctors at the Cleveland Clinic Cardiovascular Coordinating Center found that aspirin by itself was more effective and safer than taking aspirin in conjunction with blood-thinners. "There is no reason to use the combination therapy for primary prevention (of heart attacks or strokes), whereas it might be useful in patients who have already had a heart attack or stroke," said Deepak Bhatt, associate director of the Cleveland Center and a co-author of the study. The experiment, which lasted 28 months and included 15600 people over 45, actually found that a combination of aspirin and blood-thinners could actually harm some patients, like smokers or diabetics. The results of the tests were presented at the American College of Cardiology's annual congress, and will be republished in the April 20 edition of the New England Journal of Medicine.