Guidance of anticoagulation after intracoronary implantation of palmaz-schatz stents by monitoring prothrombin and prothrombin fragment 1 + 2

The primary objective of this study was to apply a sophisticated coagulation monitoring system including estimation of the concentration of prothrombin fragment 1 + 2 (PTF 1 + 2) and the activity of prothrombin (coagulation factor II or FII) to cases of stent implantation and to compare the results with those of standard coagulation tests. The secondary objective was to detect the incidence after stenting of subacute thrombosis (SAT) and bleeding complications in these patients and to compare the results with those of a group of patients with stent implantation in whom coagulation was monitored exclusively by standard tests. SAT several days after coronary stenting occurs in up to 20% despite aggressive intravenous and overlapping oral anticoagulation. According to a prospective study protocol 120 consecutive patients with implantation of 155 Palmaz-Schatz stents underwent coagulation monitoring including single daily estimation of the concentration of PTF1 + 2 (target range <0.5 nmol/L) and of FII activity (15% to 35%) in addition to the standard tests of thrombin time (TT), partial thromboplastin time (aPTT), international normalized ratio (INR), antithrombin III (ATIII), and fibrinogen. Adjustment of heparin and phenprocoumon dosages in this study group was based only on the results of PTF1 + 2 and FII measurements. A control group consisted of 53 patients with implantation of 64 stents who were matched for baseline, angiographic, and procedure-related characteristics. After stenting, anticoagulation was monitored by estimation of TT (target range>70 seconds), aPTT (>70 seconds), INR (3.0 to 4.5), AT III (>80%), and fibrinogen (<450 mg/dl) in this control group. There was a weak correlation between PTF1 + 2 and aPTT (r = 0.337; PTF1 + 2 = −0.00169aPTT + 0.491) and PTF1 + 2 and TT (r = 0.328; PTF1 + 2 = −0.00142TT + 0.494). A better correlation was found between FII and INR (r= 0.983; FII = −23.8 INR + 134). Stable oral anticoagulation was maintained 2.8:± 0.9 days later according to an FII concentration of <35% compared with an INR>3. The incidence of SAT was 3.3%, with 3.0% for elective versus 3.8% for nonelective stenting. The sensitivity, specificity, and accuracy of the PTF1 + 2 test were 100%, 88%, and 88%, respectively. In the control group the incidence of SAT was 17%, with 16.1% for elective versus 18% for nonelective stenting. Major bleeding complications occured in 10% (study group) and in 11.3% (control group) of patients (no statistical difference). The mean duration of hospitalization was 12.8 ± 2.8 days in the study group versus 8.2 ± 3.1 days in the control group (p < 0.0001). In conclusion, monitoring of PTF1 + 2 and FII is a better way to guide anticoagulation after intracoronary stenting than the use of standard tests. Prothrombin activity more precisely identifies stable oral anticoagulation. This more sophisticated coagulation monitoring was associated with a reduced rate of SAT for elective and nonelective stenting and did not increase the rate of bleeding complications, but it significantly prolonged hospitalization.