, nicorandil , nitrates are other anti anginal drugs.
if he is retaing fluids- take less salt, and take only 1.5 liter fluid per day ,its mean that ejection fraction
of your son is less or kidney disease
he is too symptomatic , so you should take another opinion of interventional cardiologist for angioplasty
or cardio thoracic surgeon for coronary artery bypass surgery