Antithrombotic Therapy in Patients With Saphenous Vein and Internal Mammary Artery Bypass Grafts Following Percutaneous Transluminal Coronary Angioplasty

1. It is standard practice, in patients undergoing coronary angioplasty, to administer heparin during the procedure. The usual dose is 10,000 U administered intravenously, followed by a continuous infusion or intermittent heparin to maintain therapeutic levels. We found no evidence to indicate that this standard should be modified.

2. There is no evidence that prolonged (18 to 24 h) heparin is of any benefit over a few hours in preventing acute thrombosis in patients who had uncomplicated procedures (level II). Based upon standard practice, heparin for 16 to 24 h is administered for unstable angina, complex lesions, multivessel angioplasty, and a suboptimal result.

3. Antiplatelet agents (in addition to heparin) reduce periprocedural coronary thrombosis and are indicated (level I and II studies).

4. Aspirin alone was as effective as aspirin plus dipyridamole (level II).

5. The dose of aspirin that was used in most studies was 650 mg/day to 990 mg/day (although sometimes with dipyridamole), and aspirin was started before the angioplasty. Lower doses of aspirin (80 mg/ day), started one day before the angioplasty, were also effective (level II).

6. The evidence that antiplatelet agents may prevent or modify late restenosis is inconsistent (level II), (level IV), (level I).

7. Warfarin, in small size studies, was not effective in preventing late restenosis (level II), but it was not worse than aspirin (level II).