My father in law 54 who was diagnosed to hav single vessel disease, lft main, is on medications, recently found to hav pedal oedema.. is it serious ?

Leg Edema: Your father obviously has a cardiologist. Your questions should be directed to him. Your father needs an echocardiogram and if his ejection fraction is good, he needs to be investigated for kidney disease, by a nephrologist, or varicose veins, by having a venous doppler study of his leg veins. To see if one or both of these are responsible for his edema. Good luck.

It could be a side: Effect of his medication. Let him mention it to his dr to be sure it's not a sign of kidney problem or heart failure. Bless you :).