I am not sure how anyone here would know if it was a heart attack or not. That would be really hard to determine. Although people often say "heart attack" when they mean cardiac arrest. A heart attack is a MI, or block in a coronary artery. Cardiac arrest is your heart stopping. If they were doing CPR, then he was in Cardiac arrest. Could easily of been caused by a fall and head injury, or he could of had an MI, then fell.
As far as the aspirin a day, it does not prevent your arteries from getting plaque deposits. What is will do is decrease the number of plateletes that aggregate when that plaque ruptures, thus reducing the size of the embolis and possibly reducing heart muscle damage.
That being said, aspirin has its own risks. If you are 30 and drink a decent amount, you have a higher chance of dying from a GI bleed with aspirin than you do from dying from an MI without. An MI in your 30's is very rare unless you have a strong family history of known risk factors (smoker,obese, high cholesteral, high BP).
If this is the case, talk to your doc before you start taking meds daily, even aspirin.