You may never need further intervention. CAD progression almost always can be stopped if medication, diet, lifestyle, etc. take effect. There may be a time in 5 years or more where CAD can be reversed.
I don't think anyone can answer that question. Alot depends on how well you take care of the things you can control. Things like diet and exercise have alot to do with how well your heart ages. How much damage your heart suffered during your other heart attack also plays a significant role in how well it responds to treatment as well. I know several people that suffered a heart attack and have done very well with no additional problem for 20 to thirty years as of this writing.
Attitude is also very important as it has a direct relationship on how well you handle stress and how your heart reacts to that stress. Your heart is an amazing thing and will continue to do its' job given a chance. I know this because I have a bad one and yet it still keeps me going after 5 years and lots of problems. I was 49 when I had my second heart attack and first CABG x 5. I have had angioplasty, lots of heart caths, an ICD, EF less than 20, heart failure and cardiomyopathy. I also have lots of new blockages that can't be fixed anymore because of extensive heart disease and yet life is good and there is lots to smile about.
So hang in there, follow the rules and keep on smiling.