Reactive thrombocytosis following coronary artery bypass surgery: a possible link to a lipid dysfunction.

Reactive thrombocytosis (RT, Platelet counts >400x10(3)/mm3) following coronary artery bypass grafting (CABG) has earlier been described to occur frequently (20%) and is associated with thrombotic complications eg. vein graft occlusion. This prospective study was undertaken in an attempt to identify the underlaying causes of RT following CABG. Fourty consecutive patients undergoing elective CABG entered the study, between December 1, 1994 and April 15, 1995. Patient characteristics, operation data, cardiopulmonary data and postoperative complications (30 parameters) were entered into a database together with routine blood chemistry and hematology results, hemostasis and antiinflammatory (eg.IL-6) parameter (25 parameters/day), preoperatively until the 9th postoperative day. Fifteen patients developed RT and the remaining 25 served as controls (C). Fourteen patients, chosen at random, received Aspirin, 100 mg daily, starting from the 3rd postoperative day, all patients were anticoagulated postoperatively with heparin and later coumarine. Patient characteristics, except a larger number of patients with hyperlipidemia in the RT group, did not differ. Operation data, cardiopulmonary bypass data as well as postoperative complications revealed no group differences, neither did preoperative laborations, except that S-Cholesterol was higher in the RT-group, 6.2+/-0.9 vs 5.3+/-0.9, p<0.018. All blood laborations were without group differences throughout the entire study period, except platelet counts, platelet size (PWD) and mean platelet volume (MPV), and AT III levels at the 7th postoperative day, which was significantly lower in controls compared to RT. RT patients had a less marked drop in platelet count immediately after cardiopulmonary bypass than non-RT together with an increased MPV, but without differences in the PWD. There was a significantly higher platelet count in the RT-group on the 3rd postoperative day, which remained higher throughout the study period and RT was established on the 7th postoperative day. Additional treatment with Aspirin postoperatively did not influence studied parameters. This study has again found RT frequently occurring after CABG (30%). It was found that the preoperative S-Cholesterol level was significantly higher in the RT group, while hemostasis and anti-inflammatory parameters did not differ RT vs non-RT. It could therefore be possible that RT is linked to a lipid dysfunction and further studies are on-going.