That's a tough weekend! I've done the ER with chest pains thing myself (what a goat-rope) and for me thankfully it was "nothing". I'll keep your Dad in my prayers.
Now, the docs do the low fat/sodium speech - and if your Dad wants to be miserable then he should follow the doc's advise. Unless he's got one of the progressive quacks that believes there's more to life than the number of days!
Now, I'm speaking as a diabetic - not a cardiac survivor - EXERCISE WILL MAKE MORE DIFFERENCE IN CHOLESTERAL, ETC. THAN ANYTHING ELSE.
I honestly mean that! I eat meat, eggs, cheese (hey, I'm diabetic and can't eat breads, cereals, rice, etc.), etc. and my blood work came back the best it's been in years: total cholesteral way down, LDL/HDL right smack where they should be, and the triglycerides made the doc grin! I also contol my blood pressure and sugar with my diet and exercise.
Buy your Dad a new pair of New Balance walking shoes and get out there with him! The year after I was diagnosed with diabetes I did a full marathon, walking, in 6:59 :D I still walk but now I powerlift with my sons (205 squat, 135 bench (wuss!), 285 deadlift), watch what I eat, and take my supplements. I'm not on any diabetic medication at this time - my morning blood checks come in at 85-110 each day
Sorry, didn't mean to start a rant! But there is life after a serious diagnosis.
Encourage your Dad to deal with this aggressively! Work with the doc/nutritionist! If you live close by then you should get out with hime and exercise.
Heck, I'm 52 and am in the process of being in the best shape I've been since about 1978.