CPT code 93459 describes catheter placement in coronary artery(s) for coronary angiography, including intraprocedural injection(s) for coronary angiography, imaging supervision and interpretation; with left heart catheterization, including intraprocedural injection(s) for left ventriculography, when performed, catheter placement(s) in bypass graft(s) (internal mammary, free arterial, venous grafts) with bypass graft angiography.
CPT code 93458 describes catheter placement in coronary artery(s) for coronary angiography, including intraprocedural injection(s) for coronary angiography, imaging supervision and interpretation; with left heart catheterization, including intraprocedural injection(s) for left ventriculography, when performed.
So it is clear that 93459 includes catheter placement(s) in bypass graft(s) (internal mammary, free arterial, venous grafts) with bypass graft angiography.
In my opinion 93459-26 is more appropriate.