How can someone not notice that they have had repeated heart attacks possibly over more than a span of a year?

Unlikely. Although we occasionally find evidence for an old heart attack in patients with no history of a heart attack, it is possible that that person had pain in the past and just thought it was indigestion or something else. To have repeated heart attacks without pain or other symptoms would be unlikely. Remember, there are many heart problems that are not really a heart attack. Some get confused by that.
Denial and atypical. Atypical symptoms mistaken for something else like indigestion or denial.