An angiogram can be performed with a cath (intervention with a probe through the
leg vessel to
the heart), or ct scan (best is a 128 slice) that views
the blood flow (dye has been injected) through the coronary arteries.
There isn't a high risk with a cath, and it is not painful, but have an understanding with the doctor whether or not your father wants a stent implant if there is some blockage, and whether the stent(s) are drug coated or not (obtain an opinon what the doctor prefers).