Platelet function tests predict bleeding and thrombotic events after off-pump coronary bypass grafting.
OBJECTIVE
A balanced coagulation system after cardiac surgery minimizes bleeding and thrombotic events. However, the best method to monitor this balance has not been established. We used a series of tests of coagulation and platelet function to define the risk of bleeding and thrombotic events after OPCAB.


METHODS
In 76 patients, routine coagulation tests (i.e. prothrombin time, fibrinogen level, d-dimer, and platelet count), thrombelastography, and whole blood aggregometry were obtained perioperatively and on days 1 and 3 after OPCAB. Intra- and postoperative blood loss was determined. Early patency of venous bypass grafts was determined using CT angiography (Philips Medical, Corp.).


RESULTS
Chest tube output and red cell volume loss at 24 h were 952+/-475 and 190+/-115 ml, respectively. Early graft failure developed in eight patients. Perioperative changes in routine coagulation tests showed no correlation with either bleeding or thrombosis. However, perioperative decline in platelet function as assessed by the area under the impedance curve for whole blood aggregometry correlated with intraoperative blood loss (R=0.42, P<0.05). A perioperative decline in the maximum amplitude of the thrombelastography trace showed a significant correlation with 24h hemoglobin loss (R=0.45, P<0.05). Compared to those with all patent grafts, patients with early graft failure demonstrated a reduction in platelet sensitivity to aspirin by both thrombelastography and aggregometry on day 3.


CONCLUSIONS
In contrast to standard coagulation testing, platelet function predicted both bleeding and thrombosis after OPCAB. Titration of perioperative platelet function according to these tests may minimize thrombosis without increasing bleeding.
Poston
Robert
R
Division of Cardiac Surgery, Department of Surgery, School of Medicine, University of Maryland, N4W94 22 S. Greene St., Baltimore, MD 21201, USA. rposton@smail.umaryland.edu
Gu
Junyan
J
Manchio
Jeffrey
J
Lee
Andrew
A
Brown
James
J
Gammie
James
J
White
Charles
C
Griffith
Bartley P
BP
D000368:Aged; D001780:Blood Coagulation Tests / Q000379:methods; D001792:Blood Platelets / Q000502:physiology*; D047549:Coronary Artery Bypass, Off-Pump / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging; D006084:Graft Rejection; D006801:Humans; D008297:Male; D008875:Middle Aged; D019990:Perioperative Care / Q000379:methods; D010979:Platelet Function Tests / Q000379:methods; D019106:Postoperative Hemorrhage / Q000209:etiology*; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D013927:Thrombosis / Q000000981:diagnostic imaging / Q000209:etiology*; D014057:Tomography, X-Ray Computed; D014654:Vascular Patency