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Antithrombotic Therapy in Patients With Saphenous Vein and Internal Mammary Artery Bypass Grafts Following Percutaneous Transluminal Coronary Angioplasty
Section snippets
SAPHENOUS VEIN BYPASS GRAFTS
Over one half of the randomized prospective studies of anticoagulants or antiplatelet agents on saphenous vein graft closure have shown a beneficial effect of therapy1, 2, 3, 4, 5, 6, 7, 8, 9 (Table 1). This applies to studies of aspirin alone in various doses,1,3 aspirin plus dipyridamole,3, 4, 5, 6 sulfinpyrazone,7 ticlopidine,9 and warfarin.8 Studies in which aspirin was administered before operation3 or within one day after operation1 showed a beneficial effect, irrespective of the dose of
INTERNAL MAMMARY ARTERY BYPASS GRAFTS
Regarding the use of antìplatelet agents in patients with internal mammary artery bypass grafts, information is limited. Among 45 patients with left internal mammary artery to left anterior descending coronary artery bypass grafts, 18 received aspirin, 1,300 mg/day, as well as dipyridamole, 100 mg/day, beginning one day after operation.6 Following three to six months of observation, graft patency was similar in the control and treatment groups: 26 of 27 (96 percent) vs 18 of 18 (100 percent)
BLEEDING COMPLICATIONS: CORONARY ARTERY BYPASS GRAFTS
Information regarding bleeding complications of various regimens of antithrombotic therapy following saphenous vein bypass graft surgery is sparse. In a retrospective study, the estimated odds ratio for reoperation for bleeding following coronary artery bypass grafting was 1.82 among patients who received aspirin (dose unstated) within seven days prior to surgery (level IV).23 Among patients in whom chest tube drainage was measured, those who received aspirin prior to surgery had more chest
SUMMARY: CORONARY ARTERY BYPASS GRAFTS
- 1.
Aspirin alone may be as effective as aspirin in combination with dipyridamole when both are started before operation,3 but aspirin plus dipyridamole is more effective than aspirin alone, when dipyridamole is started before surgery and aspirin is started after operation.21
- 2.
Aspirin, 325 mg/day, is as effective as aspirin, 975 mg/day, or aspirin, 975 mg/day, plus dipyridamole, 225 mg/day,3 and both are more effective than sulfinpyrazone.3 Bleeding may be less with the lower dose of aspirin.3
- 3.
Aspirin
PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY (PTCA)
Antiplatelet agents, when started before the procedure, have been shown to be beneficial in the prevention of periprocedural events associated with PTCA (level I, II studies)26,27 (Table 4). Fewer patients had myocardial infarctions and fewer required emergency coronary artery bypass grafts when aspirin plus dipyridamole or ticlopidine was administered prior to PTCA26,27 (Table 4).
Patients who, starting before the procedure, were administered aspirin alone or in combination with dipyridamole,
LONG-TERM EFFECTS AND LATE RESTENOSIS
Regarding restenosis, antiplatelet agents have shown inconsistent benefits (Table 5). Schwartz and associates26 showed a similar number of patients with restenosis four to seven months after PTCA among patients treated with aspirin, 990 mg/day, plus dipyridamole, 225 mg/day, vs placebo, 46 of 122 (38 percent) vs 49 of 127 (39 percent) (NS) (level II). The severity of restenosis, however, was less in the 40 segments in the active treatment group than in the 46 segments in the placebo group (mean
RECOMMENDATIONS: CORONARY ARTERY BYPASS GRAFTS
- 1.
It is recommended that antiplatelet agents be administered to reduce the frequency of saphenous vein bypass graft closure. This recommendation is based upon several level I and level II studies that showed significant benefits of therapy,1,3, 4, 5, 6, 7,9,17 as well as meta-analysis that included additional studies, the individual results of which did not reach significance.16
- 2.
Aspirin alone is recommended. The dose of aspirin that has been shown to be beneficial in graft patency in rigorously
RECOMMENDATIONS: PTCA
- 1.
Heparin, 10,000 U intravenously, followed by a continuous infusion of heparin, or intermittent heparin to maintain the activated partial thromboplastin time 1.5 to 2 times control is recommended on the basis of standard practice.
- 2.
It is recommended that heparin be discontinued 2 to 4 h after the conclusion of an uncomplicated procedure (level II).33 Based upon standard practice, heparin for 16 to 24 h is recommended for unstable angina, complex lesions, multivessel angioplasty, and a suboptimal
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