There are different intensities to myocardial infarction. A very strong case of angina can feel just the same as a heart attack. If you are showing low levels of troponin in your blood and your ecg doesn't look bad, then you will not be classed as an emergency. The medication you will have received virtually on arrival will have thinned the blood enough to seriously lower the risk of another attack and with no exertion you would have been much safer.
With regards to your length of life, I think you should be very optimistic. Every single day research is going on all over the world and knowledge/treatments is growing all the time. They are even able to take stem cells out of mice/rabbits and grow complete replacement hearts in the lab now. It won't be much longer before it will be available for humans, I estimate another 10-20 years. You only had one bad blockage which has been opened up now, so you have no worries. As RSO has said, eat healthy and exercise every day. You will be on the plavix for 12-18 months but aspirin for life. I would question if you can come off the beta blockers in the near future because they can play havoc with your life style. I found they destroyed my sex drive, made me lethargic and gave me symptoms I could have done without. Maybe go onto a blood pressure medication (ace inhibitor) instead. Not all cardiologists now agree to automatically prescribe beta blockers, in fact my new cardiologist insisted I came off them.
So keep smiling, be chilled and enjoy a long life. Its not all doom and gloom by a long shot.
At 42 and with a double bypass after a heart attack I'm told I wont live very much longer. If fact they believe I'll be very lucky if I live another 58 years and extremely lucky If I live an additional 10. However I personally believe I am lucky I wake up every morning. You, being a tear older, is a different story, You might have another 57 years and be lucky if an aditional 9. Having a Stent, to me, is far less scary and far easier to recuperate from than a bypass. After all, they placed something in an artery "specifically designed" to keep it open, for you. For me they added a vain where one does "not belong" and one that is "not designed" for the area it was placed. In other words, Relax! Eat right! keep fit! and you'll be fine :-)