Generally, folks notice this by a decrease in cardio vascular fitness if they are at all active. If not you suddenly find yourself gasping for air when walking up a flight of stairs or something like that.
In my case, I knew I had a blockage because I used to run religiously and I couldn't even run a mile without getting winded when I had a blockage.
Thank you for the information.
I knew it when I had the heart attack.(P.S. I didn't run religiously).
Prayers for President Clinton and his family.