Elective coronary arteriography should be performed alone or in conjunction with right-heart catheterization or contrast-enhanced left ventriculography (see  Chap. 20) when comorbid conditions, such as congestive heart failure, diabetes mellitus, or renal insufficiency, are stable. A baseline electrocardiogram, electrolyte and renal function tests, complete blood cell count, and coagulation panel should be reviewed before coronary arteriography. Patients who may undergo PCI should receive aspirin, 162 to 325 mg, at least 2 hours before the procedure if PCI is planned. Warfarin should be discontinued 2 days before elective coronary arteriography, and the INR should be less than 2.0 before arterial puncture when the femoral artery access is used. Higher INR (up to 2.5) may be acceptable when transradial access is performed.^[31,32]Patients at increased risk for systemic thromboembolism on withdrawal of warfarin, such as those with …