Long term clinical outcome of coronary surgery and assessment of the benefit obtained with postoperative aspirin and dipyridamole.

Three hundred and twenty patients originally entered into a randomised study to assess the effect of aspirin and dipyridamole on the patency of coronary bypass grafts one year after operation were clinically reassessed a mean of 6.6 years (range 4.3-8.6) after operation. Patients were recruited between 1978 and 1982 after the present policy of total revascularisation had been adopted. During the follow up period there were 25 deaths of which 17 were due to cardiac causes (average annual cardiac mortality 0.8%). Of 280 patients available for contact, 250 (89.3%) attended an outpatient interview. Ninety four (37.6%) patients complained of recurrent angina but in only 23 (9.2%) was this severe. Two hundred and eleven (84.4%) of the 250 patients underwent exercise stress testing. There were 73 (34.6%) abnormal tests of which 52 were in the group of 94 patients with recurrent angina. Myocardial infarction occurred in nine of the 250 patients during the follow up period. Twenty six patients (10.4%) had reinvestigation for symptoms. This group had a graft occlusion rate of 52%. Half these patients have required reoperation and 20 of 22 occluded or severely stenosed grafts were replaced. In only two instances were vein grafts inserted into vessels with new disease. Half of the original group were given aspirin (330 mg three times a day) plus dipyridamole (75 mg three times a day). Of the 250 patients interviewed, 122 took aspirin and dipyridamole from the second postoperative day for a mean of 25 months, with warfarin for three months. The other 128 patients took placebo for a mean of 23 months together with warfarin for three months. This long term treatment with aspirin plus dipyridamole conferred no significant benefit for all clinical outcomes measured at a mean of 6.6 years.