Monitoring anticoagulation following intracoronary procedures: which method?

We have assessed bedside kits for monitoring the activated partial thromboplastin time and the activated clotting time by comparing them with laboratory activated partial thromboplastin time values. To determine the accuracy of anticoagulation we have concurrently measured the plasma heparin concentrations, and plasma prothrombin fragment F1 + 2 concentrations. Serial samples were taken from patients undergoing elective percutaneous transluminal coronary angioplasty (n = 14). Readings were taken pre-procedure, 30 min after administration of a heparin bolus (10,000 U) and 1, 2 and 3 h after commencement of a constant heparin infusion (15 U/kg/h) postprocedure. Activated partial thromboplastin time results obtained with the bedside kit compared reliably with laboratory values (r = 0.8), were rapidly available and were reflected by appropriate changes in prothrombin fragment F1 + 2 and heparin concentrations. However, the relationship between activated partial thromboplastin time values and activated clotting time was less precise (r = 0.59). Therefore, for routine and frequent monitoring of anticoagulation with heparin, a bedside activated partial thromboplastin time kit provides adequate control of therapy but in instances were particularly tight control of anticoagulation is required, use of prothrombin fragment F1 + 2 concentrations may be more appropriate.