COMPARISON OF HEMOCHRON AND HEMOTEC ACTIVATED COAGULATION TIME TARGETVALUES DURING PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY

Objectives. The aim of this study was to determine whether activated c oagulation time measurements from Hemochron and HemoTec machines can b e used interchangeably and whether similar activated coagulation time target ranges for adequate anticoagulation can be applied to both mach ines. Background. Adequate anticoagulation is necessary for the safe p erformance of intravascular interventions such as percutaneous translu minal coronary angioplasty. In current practice, anticoagulation statu s is frequently assessed by way of the activated coagulation time with one of two commercially available systems, HemoTec and Hemochron. Eac h one employs a different technique to determine the time of clot form ation; however, the same target activated coagulation time values for adequate anticoagulation have been used interchangeably in published s tudies. Methods. A total of 311 paired samples were compared in 113 hi gh risk patients undergoing angioplasty enrolled in a randomized trial of a platelet glycoprotein IIb/IIIa receptor antibody. Simultaneous a ctivated coagulation time measurements were obtained before and after administration of heparin, and the difference between the values of bo th machines was calculated. The relation between the Hemochron and Hem oTec values was determined by using linear regression analysis. Ah act ivated coagulation time measurements were classified as either therape utic or subtherapeutic using an arbitrary activated coagulation time t arget of 300 s. Results. There was a correlation between values from t he two machines (r = 0.86), but the Hemochron values were consistently higher than the HemoTec values by a mean value +/- SD of 28 +/- 29%, with wide individual variation. After heparin administration, there wa s a significant (p < 0.0001) difference between the number of measurem ents classified as therapeutic by HemoTec (53%) and by Hemochron (94%) . Conclusions. HemoTec and Hemochron activated coagulation time measur ements cannot be used interchangeably. Appropriate target activated co agulation time ranges to determine adequate anticoagulation during cor onary angioplasty need to be established for both machines; the target range for one machine should not be extrapolated to the other.