Antiplatelet therapy following carotid bifurcation endarterectomy. Evaluation of a controlled clinical trial. Prognostic significance of histologic plaque examination on behalf of survival

Abstract

To determine whether antiplatelet therapy following carotid bifurcation endarterectomy influences postoperative survival and whether signs of progression in the plaques harvested at the time of surgery might be a prognostic indicator, a controlled clinical trial was undertaken. During 1982 to 1985, 66 patients were recruited, operated on (carotid endarterectomy) and assigned, using the method of adaptive randomisation to the therapy group (n = 32) receiving 1.0 g acetylsalicylic acid (ASA) per day, starting day two prior to surgery, or to the control group (n = 34), which remained without antiplatelet medication. The plaques harvested at the time of surgery were processed using standard histopathological methods and examined "blindly" by light microscopy for signs of arterio-sclerotic progression. The final endpoint was patient survival. The last assessment of the participants survival status was done by June 1989. During follow-up, 20 patients died, six in the treatment group and 14 in the untreated group, the difference being statistically significant (P less than 0.013 Breslow, P less than 0.029 Mantel). In 27 instances the histo-pathological examination showed signs of progression. In this subgroup ASA yielded a significant prolongation of patient survival (P less than 0.017 Breslow, P less than 0.048 Mantel). In the remaining patients no signs of cellular infiltration were evident and no influence of ASA on patient survival was demonstrable (P less than 0.503 Breslow, P less than 0.390 Mantel).