If there is a blockage for heart blood vessels I would like to know how many and what % blockage is present.
Now here I would give 2 option
One is that to go for surgery
And 2 is try with there is some thing called as coenzyme q 10 along with omega 3 and
vitamin c. I give here my patient a natural organic supplement. Here Co enzyme q 10 will help to get energy for heart, omega 3is natural blood thinner as well anti inflammatory and helps for many other function, vitamin c is blood purifier also called as anti oxidant. All this you can try for 1month and look for symptomatic improvement. Once you find him improving can continue further for few more month and then again go for heart check up to review the case.
One more thing ask him to have his blood pressure tablets regular and don't miss on that. As well he should also check once with doctor if symptoms like too much
tiredness with 10 step walk or continue sleeping for most of time. Because that shows that the heart is not able to function properly due to blockage.
Don't worry if he needs to go for surgery too. All most all the cases after heart surgery gets all right in a day or 2 and it will not be a painful process also so don't take tension just apply the things I share.
Hope this was helpful for you. Take care