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

Reactive thrombocytosis (RT) has earlier been reported to occur as a r esponse 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 thr ombocytopenia that occurs after cardiopulmonary bypass (CPB) and the r isk of postoperative bleeding, rather than the possibility of a late o ccurrence of RT as a risk factor for thrombotic complications after co ronary artery bypass grafting (CABG). Between 1989 and 1992, on routin e blood examinations we noticed a group of CABG patients (n=297, Group II, 19.5%) that, 1 week after operation, showed thrombocytosis with s ignificantly increased platelet count (52 +/- 96 x 10(3)/mm(3)) compar ed to patients with normal platelet counts (Group I, n=1521, 185 +/- 1 25 x 1O(3)/mm(3)); P<0.001. Patient characteristics, coronary angiogra phy findings, operative data and perioperative complications were anal yzed for the two groups. There were significantly more patients with h gperlipidemia, smoking and previous myocardial infarction in Group II than in Group I; P<0.05. Age, sex, clinical characteristics, angiograp hy findings and operative data did not differ between the groups. Ther e were no differences in postoperative bleeding or the need of transfu sion between the groups. However, Group II (RT) patients had significa ntly more postoperative myocardial infarctions, 4.4% compared to 0.7% Group I; P<0.001. Early symptomatic vein graft occlusion (0-7 days pos toperatively) was not different between the groups, while there were s ignificantly move late symptomatic vein graft occlusions (7-60 days po stoperatively) in Group II (RT) 4.4% than in Group I 1.1%; P<0.001. Th is 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 posto peratively).