Hello thanks for writing us.
As you already had undergone CABG , should avoid weight gain, control your food and go for daily walking..
AS far as giddiness is concerned may be due to high B.P thats why your doctor has prescribed you Olmin-H( anti hyper tensive),.
Rancad is antianginal drug , usually prescribed for anginal chest pain
Both are safer drugs not having any interactions with the drugs you are taking
Good luck, take care