Triple bypass expectancy

I have what I have formulated to be a very unique question.  
I have concerns about my very outwardly healthy, physically and mentally active 75 year old father.
In August of 1985, after a series of tests discovering he had experienced a mild heart attack, he underwent triple bypass surgery.  One year prior to this event, he had reformed his health approach by quitting smoking and adopting a mild but regular excercise regimen in order to improve his health.  A regimen, including dietary improvements, that he has rigorously kept up ever since.
At the time the general sense was that he could expect a ten-year expectancy for the bypass which used veins from his leg.  Time went on, and on...and on.  He continues to visit his cardiologist regularly who advises he continue a better-than-exceptional cholesterol level (understandibly so) and he has not had any cardio incedents except a procedure to correct a rapid heart beat (I believe) that involved a scope which delivered a shock to regulate his hearbeat permanently last fall. It was completely successful.
We are going on 24 years now.  This, from casual medical discussion, seems to be a medical oddity.  My own family Dr., when asked off the record, indicated that my father is "Don't get me wrong--still high risk--but the body finds a way to temporarily 're-route' blood flow".  
I was 14 at the time of that bypass.  As a grown adult, I understand how fortunate I am to have experienced my father's presence in my life in all that time.  I truly would love some medical input, however, on what kind of circumstances have kept my father out of the operating room for arterial blockage 24 years after a 1985 bypass surgery and how likely it is he could conceivably stay living with borrowed arteries.
If this isn't enough, he has survived early-detected prostate cancer surgery in 1999.  He is diabetic--but as I understand that is in check as well for now.  In 2002 he almost did not wake up from surgery on his back, so I know any deep anesthesia could conceivably be his last.  Another light-anethsetic outpatient procedure this year for carpal tunnel (January) went fine as did the aforementioned irregular heartbeat situation in the fall.
This could quite easily be the longest, most unbelievable forum subject I have seen here but it is about my dad.  So feel free to lend input but please be gentle.  

J.

[Encephalomalcia]

Your Dad is very fortunate that everything went well for him and that he continues to do well.  Bypass surgery is sometimes a fix in that the bypasses are put in straight.  What may have caused his blockage was bent arteries.  Also, inflammation can cause cholesterol to stick in the arteries.  Diet, exercise all help tremendously.  Sounds like he is taking good care of himself.  Arteries do reroute and the heart does grow new arteries in some people, but not all people.  My grandfather was fortunate in that he had heart failure, but he grew new arteries.  When this happened to him many many years ago, he was in a study at the University of Minnesota.  Now with stem cell research, they have discovered the key to growing new arteries.  I do not believe it is being done here in the US yet, but is being done in our countries.  People on this forum have had the stem cells from their own body to improve cardiomyopathy.  Your dad is also very fortunate in that the heart shock worked in restoring his heart rhythm to normal.  This does not work on everyone.  It worked on my mom, but not my dad.  My dad has to take Coumadin to reduce his chance of a stroke from the risk of blood clots due to an irregular heart beat.  Sounds like he has a good chance of his bypasses lasting his entire life.