MULTIVARIATE-ANALYSIS OF RISK-FACTORS FOR THROMBUS FORMATION IN UNIVERSITY-OF-TOKYO VENTRICULAR ASSIST DEVICE

Of 77 University of Tokyo ventricular assist devices used in a total o f 70 patients at 21 institutions, 13 pumps were found to have macrosco pic thrombus formations. Because 19 devices that were used for less th an 24 hours showed no thrombus deposition, they were considered not to have been sufficiently exposed to the thrombogenic environment for ma croscopic thrombus deposition and were removed from the subsequent mul tivariate study. A total of eight potential risk factors were assessed in relation to thrombosis. Prevalences of thrombus formation were com pared between two groups with or without each of the risk factors. In a univariate analysis, the following categoric variables were demonstr ated to be significantly associated with complications, in descending order of significance: use of gabexate mesilate (protease inhibitor) a s an anticoagulant (p = 0.005), normal platelet count (p = 0.010), dur ation of support (p = 0.038), leukocytosis (p = 0.042), and minimum pu mping flow (p = 0.042). Use of heparin and the consequent increase in activated clotting time showed no relationship. Multivariate discrimin ant analysis, which was done to identify risk factors rejecting cross correlation between each variable, demonstrated platelet count (p = 0. 006), use of gabexate mesilate (p = 0.007), and minimum flow (p = 0.00 8) to have significant and independent risks. These results indicate t he importance of maintaining pumping flow above a certain minimum leve l, addition of antiplatelet drugs to the antithrombogenic regimen, and nonuse of gabexate mesitate.