REACTIVE THROMBOCYTOSIS AFTER CORONARY-BYPASS SURGERY - AN IMPORTANT RISK FACTOR

Reactive thrombocytosis (RT) has earlier been reported to occur as a response to various situations and conditions, such as post-splenectomy, hematopoietic disorders, major trauma and operations, neoplasms and inflammations. In cardiac surgery the main interest has focused on thrombocytopenia that occurs after cardiopulmonary bypass (CPB) and the risk of postoperative bleeding, rather than the possibility of a late occurrence of RT as a risk factor for thrombotic complications after coronary artery bypass grafting (CABG). Between 1989 and 1992, on routine blood examinations we noticed a group of CABG patients (n=297, Group II, 19.5%) that, 1 week after operation, showed thrombocytosis with significantly increased platelet count (52 +/- 96 x 10(3)/mm(3)) compared to patients with normal platelet counts (Group I, n=1521, 185 +/- 125 x 1O(3)/mm(3)); P<0.001. Patient characteristics, coronary angiography findings, operative data and perioperative complications were analyzed for the two groups. There were significantly more patients with hgperlipidemia, smoking and previous myocardial infarction in Group II than in Group I; P<0.05. Age, sex, clinical characteristics, angiography findings and operative data did not differ between the groups. There were no differences in postoperative bleeding or the need of transfusion between the groups. However, Group II (RT) patients had significantly more postoperative myocardial infarctions, 4.4% compared to 0.7% Group I; P<0.001. Early symptomatic vein graft occlusion (0-7 days postoperatively) was not different between the groups, while there were significantly move late symptomatic vein graft occlusions (7-60 days postoperatively) in Group II (RT) 4.4% than in Group I 1.1%; P<0.001. This study demonstrates the presence of RT occurring frequently (19.5%) after CABG operations, which appears around the 7th postoperative day associated with a significantly higher incidence of late postoperative myocardial infarction and late vein graft occlusions (7-60 days postoperatively).