Improved graft patency in patients treated with platelet-inhibiting therapy after coronary bypass surgery.

Abstract

One hundred forty-seven consecutive coronary bypass patients were enrolled in a randomized, double-blind, risk-stratified, placebo-controlled prospective trial evaluating the effect on graft patency of 325 mg tid aspirin (ASA) plus 75 mg tid dipyridamole (DP) or ASA alone. One hundred twenty-seven patients (399 total grafts) underwent surgery, initiation of drug therapy 67 +/- 27 (SD) hr postoperatively, five clinic visits, and repeat angiography at 1 year. A logistic regression statistical model was used to determine the effects of 28 different measured variables on graft patency and to adjust for these effects in determining the relationship between antiplatelet therapy and graft occlusion. No patient-specific variable contributed significantly to the prediction of occlusion in either the placebo or the treated group. Six graft-specific variables (arterial diameter, severity of stenosis, graft flow, reactive hyperemia, presence or absence of collaterals, and graft type) did contribute and were included in the model. Twenty-one percent of placebo-treated grafts became occluded. Compared with placebo, the relative risk of graft occlusion with ASA was 0.47 (p = .04); with ASA + DP, it was 0.50 (p = .04). This benefit was principally due to reduction of occlusion in the most common and presumably most important groups of grafts, those in which flow exceeded 40 ml/min, or supplying arteries having luminal diameters greater than 1.5 mm. Grafts lacking reactive hyperemia had a 32% occlusion frequency in placebo-treated patients; relative risk of their occlusion averaged 0.26 (p less than .01) with platelet-inhibiting therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in early saphenous vein graft patency after coronary artery bypass surgery with antiplatelet therapy: results of a Veterans Administration Cooperative Study.

“…This possibility is consistent with previous reports in which postoperative antiplatelet therapy was more effective if begun within 24 hr after surgery than when started later. 2 The present study demonstrates that aspirin increased measured blood loss and increased the transfusion requirements of red blood cells and platelets. Moreover, there was an increased frequency of reoperation in all aspirin groups.…”

“…The traditional method of analysis in previous studies examining the effects of antiplatelet agents on graft patency assumed that grafts within patients were independent and that the patency rate was not related to any particular patient characteristic. Since that hypothesis has never been tested, we analyzed the data three ways: (1) using a cluster sampling 1330 approach in which all the grafts within each patient were grouped together, (2) assuming the grafts were independent, and (3) comparing the proportion of patients manifesting any occluded grafts. A more detailed description of the statistical analysis, including evidence of dependency among grafts, is contained in the Appendix.…”

Aspirin Resistance: Current Status and Role of Tailored Therapy

“…70 Similarly, 100 mg of aspirin had a similar antithrombotic profile as 1200 mg of aspirin in preventing the incidence of early graft occlusion following CABG. 71 Even aspirin doses as low as 50 mg per day are equally as effective as 100 mg per day at preventing cardiovascular events in patients with coronary heart disease. 72 Among high-risk patients, there is some evidence that lower doses of aspirin may in fact be superior to high-dose aspirin at reducing serious vascular events.…”

Secondary prevention of heart disease amongst patients with lipid abnormalities: practice and trends in the United States

“…Of patients undergoing this procedure for angina (many with two-and three-vessel disease), 70-80 % will enjoy sustained (3-year) pain relief, 15 % only transient or minor relief and 3 % will die. Early graft occlusion is effectively reduced by ASA [15,16]. Progressive atherothrombotic obstruction of the saphenous vein grafts limits the long-term effectiveness of CABG ; in many, angina recurs due to graft closure within 5-15 years [5,17,18].…”