The usual protocol is to treat occlusions greater than 70% blockage with a stent. Many people with a 60% blockage don't experience symptoms, but apparently you're experiencing symptoms (angina) because your mediction is for angina relief. Isisorbide for a slow release and nitro for immediate relief.
The pain usually indicates heart cells are not getting sufficient blood/oxygen, and the medication dilates coronary arteries.
There is stable angina, meaning pain only with exertion and sometimes emotions, and unstable angina indicates pain with or without exertion (usually the advanced stage).
If medication does not provide relief then a stent, but if medication helps many people would opt for the medication and no stent. Stents can be problematic causing restenosis within a year.