Prevention of early aortocoronary bypass occlusion by low-dose aspirin and dipyridamole. Grupo Español para el Seguimiento del Injerto Coronario (GESIC)

To analyze the efficacy of low-dose aspirin in preventing early aortocoronary vein graft occlusion, 1,112 consecutive patients were enrolled in a multicenter, randomized, double-blind, placebo-controlled trial comparing 50 mg t.i.d. aspirin, 50 mg aspirin plus 75 mg t.i.d. dipyridamole, and placebo. All patients received 100 mg q.i.d. dipyridamole for 48 hours before surgery, and assigned treatment was started 7 hours after surgery. Vein graft angiography was performed in 927 patients (83%) within 28 days of surgery (mean, 10 days). Aspirin plus dipyridamole significantly (p = 0.017) reduced the occlusion rate of distal anastomoses from 18% (placebo) to 12.9%. Occlusion rate in the aspirin group was 14%, which approached statistical significance (p = 0.058). Furthermore, only aspirin plus dipyridamole reduced (p = 0.01) the number of patients with occluded grafts (placebo, 33%; aspirin, 27.1%; aspirin plus dipyridamole, 24.3%). Mediastinal drainage was slightly higher (p = 0.04) in the aspirin plus dipyridamole group (713 +/- 456 ml) than in the other two groups (placebo, 670 +/- 437 ml; aspirin, 629 +/- 337 ml), but hospital mortality (average, 4.6%) and early reoperation (average, 3.9%) rates were similar among the three groups. Thus, low-dose aspirin plus dipyridamole safely improves early saphenous vein aortocoronary graft patency; this effect is an added benefit to a preoperative regimen of dipyridamole.