Very recently, I was told here by Ross that aspirin is not a recognized anticoagulant. Personally, I don't know. But I just now quickly searched aspirin and found this, cut and pasted as follows from the American Heart Association website, and I hope you find it helpful:
Anticoagulation
Some people with congenital heart defects, especially those who are cyanotic (blue), have had heart valve replacements or have had complicated surgeries such as the Fontan operation, may need to take anticoagulants (blood-thinners). These medicines slow blood clotting. They're used to prevent major complications, such as vessel or valve obstruction, or strokes. Anticoagulants may be given by mouth. In some cases they're given intravenously or by injecting them just under the skin. Bleeding may be a complication of taking these medications, so tell your cardiologist if you begin to have easy bruising, bleeding gums or nosebleeds.
Oral Medications
These mainly include aspirin (and other antiplatelet medications) and warfarin (Coumadin). Each of these medicines works on a different part of the blood-clotting cycle. Your cardiologist will decide which of these medications is right for you.
Aspirin tends to cause fewer bleeding complications. However, it may upset your stomach and be ineffective for treating your specific heart problem.
Warfarin increases your risk of serious bleeding problems. If you take warfarin, you may need to limit your activity to reduce the chance of injury, particularly a head injury. Warfarin also can cause malformations in an unborn child, so don't take it during pregnancy. Some form of anticoagulant medication as prescribed by your cardiologist and obstetrician is recommended throughout pregnancy, however. (See the section below on Subcutaneous Medications.)
Intravenous Medications
Heparin is the main intravenous blood thinner. It's used mostly in hospitals after heart operations while the dosage of the oral medication, warfarin or aspirin, is being adjusted. Oral anticoagulants are longer-acting, so if you need elective surgery (including dental surgery), these medications may need to be stopped and intravenous or subcutaneous, shorter-acting heparin begun in the hospital before surgery. Your doctor will decide if this is necessary.
Subcutaneous Medications
Heparin also can be given by an injection just underneath the skin. This is sometimes done if it's required for a longer time (e.g., during pregnancy). This usually eliminates a long-term need for an intravenous line. Both heparin and low-molecular-weight heparin are available for subcutaneous injection. Your cardiologist will determine which is best for you.
Medication Monitoring
If you're taking warfarin, to be sure your dosage is correct, your doctor will regularly monitor blood-clotting indicators. A value called the INR (international normalized ratio) tests how quickly your blood clots. Your warfarin dosage will be carefully adjusted to maintain an INR level appropriate for your heart condition. You must take your medicine exactly as prescribed. You also must have your blood tested regularly according to your doctor's orders. People on long-term warfarin therapy could ask their doctor about the possibility of self-testing their INR by using a home INR monitor.
Medication and Diet Interactions With Warfarin
Many over-the-counter or prescription medicines can interact with warfarin and change your INR, which can be hazardous. These include erythromycin, cimetidine and several pain medicines (e.g., ibuprofen and other non-steroidal anti-inflammatory drugs). There are others, too. You also shouldn't take aspirin when you're being treated with warfarin.
Certain foods also interfere with how your body processes warfarin. Your cardiologist will discuss foods to avoid or eat regularly while taking coumadin. If you're on warfarin, always ask your doctor about your diet and before taking any other medicines, including vitamins and herbal preparations."