Hopefully you are collaborating with his cardiologist as far a designing an exercise program for this man. There are specific exercises guidelines for individuals with heart disease or who have had a myocardial infarction (aka heart attack).
Beta blockers do the following:
1. Decrease resting and exercise heart rate.
2. Decrease blood pressure.
Please know that the normal exercise response is an increase in exercise heart rate and blood pressure. Hence you will not be able to determine how intense this client is working by measuring his blood pressure and heart rate. You will need to use RPE
You will also need to get clearance from his physician to exercise as he is HIGH RISK. If you don’t know the symptoms of angina, I would refer him to someone else.