Aspirin is indicated to reduce the risk of heart attack and stroke in persons who have had a previous heart attack or ischemic stroke, or who are at high risk for these events. The high-risk patient may have any of the following conditions: Previous TIA or Stroke, Chest pain (stable angina), History of heart procedures, such as angioplasty or bypass surgery, Myocardial Infarction, Peripheral vascular disease, and claudication. Aspirin therapy may be considered as a secondary prevention therapy in people with diabetes and evidence of large vessel disease.
You have not mentioned what type of surgery your wife has undergone because the prevention with Aspirin depends entirely on the risk factors that may be present and may lead to repeated strokes. Was it a heart surgery? If it was, Aspirin has to be continued for a long time to prevent clot formation. If it was not a cardiac surgery, other factors that led to clot formation previously that may still be the risk factors have to be taken into account before stopping Aspirin.
A complete blood work must be carried out and a haematologist must be consulted who will advise on the basis of the reports whether Aspirin could be stopped. There could be a number of factors in the body that may cause abnormal clotting.
It is true that Aspirin may cause bleeding but maintaining a low dose may not present with that risk. The benefits of using Aspirin always outweigh the harms it could cause.
Please consult a haematologist, neurologist and cardiologist before making any change in the medication.
Hope this helps you. Take care and regards!