22 Oct

Antithrombotic Therapy in Mechanical and Biological Prosthetic Heart Valves and Saphenous Vein Bypass Grafts: Saphenous Vein Bypass Grafts

Warfarin was reported by some to be of no advantage at 6 months or at 1-2 years, but a larger group of patients at 2 months showed a significant difference (90% graft patency vs 85% graft patency) (p<.015) (Table 8).
Regarding the use of anticoagulants or antiplatelet agents in patients with internal mammary artery bypass grafts, there is little information. Among 45 patients with left internal mammary artery to left anterior descending coronary artery bypass grafts, 18 received aspirin 1,300 mg/day as weU as dipyridamole 100 mg/day beginning 1 day after operation. Following 3-6 months of observation, 26 of27 (96%) of control grafts were patent, and all 18 grafts (100%) in treated patients were patent (not significant).
Among patients who received warfarin or antiplatelet agents, more mediastinal blood loss was observed postoperatively than in patients not treated. itat on

Saphenous Vein Bypass Grafts
1.    It is recommended that antiplatelet ^agents be used in patients undergoing saphenous vein bypass grafts. The clearest evidence is for aspirin 1 g/day, in combination with dipyridamole, 225 mg/day. Aspirin should be administered on the day of surgery (7 h after surgery). Dipyridamole should begin 2 days before surgery at a larger dose (400 mg/day). This grade A recommendation of aspirin in combination with dipyridamole is based on three level I studies. If aspirin was administered prior to surgery, there was an increased incidence of postoperative bleeding.
2.    Aspirin 100 mg/day alone, beginning on the day of surgery, might also be considered. The latter grade A recommendation is based on one level II study. Aspirin 325 mg/day alone or aspirin 1 g/day alone when given prior to surgery also showed advantageous effects, but was associated with early postoperative bleeding. It is recommended, therefore, that aspirin not be administered prior to surgery. This grade A recommendation is based on one level I study.
One might extrapolate these data and use dipyridamole 400 mg/day beginning 2 days before surgery, reduce it to 225 mg/day the day of surgery, and discontinue it after 1 week. In addition, use aspirin 325 mg/day beginning the day of surgery (7 h after surgery) continuing permanently. This combination of therapy may offer protection with dipyridamole while eliminating the bleeding associated with preoperative aspirin and also offer the long-term therapeutic benefits and cost-effectiveness of aspirin alone.
It is recommended that long-term warfarin therapy is not indicated to preserve patency of saphenous vein bypass grafts. This grade B recommendation is based on two negative level II studies and one marginally positive level I study and the evidence that antiplatelet agents are effective in this setting and have fewer hemorrhagic complications.

Categories: Antithrombotic Therapy
Tags: , , ,

© 2008 HIV/AIDS News & Information