Why would there be blood in the stomach after a heart attack for which an angioplasty and stents were placed?

Severe illness, such as a heart attack, can cause ulcers or gastritis just due to the stress you body is under, these are called Cushings ulcers, and are treated the same way as any other ulcer, with medications. This is probably the most common cause of blood in the stomach, however, after a heart attack, people are put on several medications which increase their likelihood of bleeding, such as aspirin, plavix (especially after stents are put in), and heparin. You may have had some small bleeding in your stomach or intestines which was not detected before you were started on these medications which these medications made worse.