Aspirin or coumadin are for clots, (Antithrombotic and Thrombolytic Therapy), the American College of Chest Physicians (ACCP) recommended coumadin for atrial fibrillation
patients at high risk
, aspirin for patients at low risk
, and either drug of patients with an intermediate risk. The ACCP defines a low-risk patient as younger than 65 years with no predisposing risk factors (e.g., previous stroke, TIA, embolism, heart failure, hypertension, diabetes).