Blood clots in past and heart problems. Should I take aspirin?

Location. Where were your clots? If you had a clot in a vein or in your heart, Aspirin isn't effective. A more potent anticoagulant is necessary. You shouldn't take both usually. If you've had an arterial clot: coronary artery, bypass graft, or stroke, Aspirin is indicated - if you're not bleeding and not at high risk of bleeding. Also, be aware that Aspirin can cause cause stomach upset and GI bleeding.