Fibrinolysis and oral anticoagulation

Fibrinolysis (1993) 7, 47-49 01993 Longman Group UK Ltd

Fibrinolysis and Oral Anticoagulation

J. W. J. van Wersch, C. H. van Mourik-Alderliesten

SUMMARY. Three patient groups under oral anticoagulation for several reasons and a group of healthy volunteers were evaluated with regard to clotting activation and fibrinolysis. The thrombin-antithrombin III complex (TAT-III) and the prothrombin fragment 1+2 (F 1+2) were used as sensitive markers of the residual of the coagulation activation. Tissue plasminogen activator antigen (t-PAag) and D-dimer were taken as fibrinolysis markers. The D-dimer/thrombin-antithrombin III and the D-dimer/F 1+2 ratios were calculated as parameters arbitrarily reflecting the positioning of the fibrinolysis/coagulation balance. We obtained both enhanced D-dimer and t-PAag levels in comparison with a reference group of healthy volunteers in two of the three studied groups. The D-dimer/TAT-III ratios and the D-dimer/F 1+2 ratios were all significantly elevated indicating a shift to fibrinolysis. This is a remarkable finding when considering the low coagulation level under oral anticoagulation. It might be a relevant side-effect of oral anticoagulation.

Evidence for an enhancement of the fibrinolytic activity under oral anticoagulation has been addressed only in a few studies. In one study,’ significantly elevated fibrin degradation products have been found under fixed minidose warfarin. In other studies this phenomenon has been observed under oral anticoagulation of high intensity. Edwards et al* found after starting oral anticoagulation grossly increased fibrin degradation products in patients with cancer and only a tendency towards elevation of these fibrinolysis markers in the oral anticoagulation control group without cancer. Grunlich-Henn et al3 reported a raise of tissue plasminogen activator levels after onset of oral anticoagulation therapy. We observed recently enhanced D-dimer concentrations in a group of oral anticoagulated patients with mechanical heart valve prosthesis.4 Aim of this study was to analyse prospectively the D-dimer and tissue plasminogen activator antigen (t-PAag) levels in patients oral anticoagulated for different reasons in order to confirm the own prior results and those of the other investigators. Moreover the D-dimer/thrombin-antithrombin III and D-dimer/prothrombin fragment 1+2 ratios (F 1+2) were calculated in order to determine the positioning of the fibrinolysis/coagulation balance.

Enzygnost@ TAT-III of Behring Corp. (Marburg, Germany) was employed. The F 1+2 was determined with the Enzygnost@ F 1+2 of Behring Corp. (Marburg, Germany). The fibrin degradation products (D-dimer) were measured by means of the D-dimer test of Boehringer Mannheim (Germany). In order to obtain an impression of the position of the balance between fibrinolysis and coagulation we calculated the D-dimer/TAT-III ratios and the D-dimer/F 1+2 ratios. The prothrombin times were assessed with the Chromoquick@ reagent of Behring Corp. (Marburg, Germany) on a Cobas Bio (Hoffmann-La Roche, Grenzach-Wyhlen, Switzerland) and were reported as INR-values. The t-PAag test was from Kabi Vitrum Diagnostica (Coaliza t-PA test). Patients Three groups of patients were evaluated, these patients were monitored routinely for oral anticoagulation use. Group 1 consisted of 60 patients with (mechanical) heart valve prosthesis (INR 4.8-2.1); group 2 consisted of 60 patients after coronary artery bypass graft surgery (INR 4.81.8), and group 3 was composed of 60 patients using oral anticoagulation after deep venous thrombosis or pulmonary embolism (INR 4.8-2.1). All patients were under stable oral anticoagulation on the basis of their actual INR values. The reference values were obtained from 50 subjectively healthy individuals (25 males, 25 females) ranging from 35-65 years (group 4).

MATERIALS AND METHODS Methods For the TAT-III

measurements

the ELISA test kit Samples

J. W. J. van Wersch, Haematological Laboratory and Thrombosis Center, C. H. van Mourik-Alderliesten, Thrombosis Center, Eastern

South-Limburg,

Blood was collected between 9 and 11 a.m. in trisodium citrate (0.11 M) containing plastic tubes

The Netherlands. 47

48

Fibrinolysis and Oral Anticoagulation

(9: 1; v/v). After centrifugation (16OOg, 20 min, room temperature) the plasma was collected, analysed for the prothrombin time and after that immediately deep frozen at -70°C until batch analysis of the specimens for the other analytes. Before analysis they were thawed with tap water for 5 min before use.

Table 1 Spearman rank correlation (p-values) between INR levels and D-dimer and t-PAag Spearman rank correlation (p-values) between INR (4.8-1.8) and D-dimer t-PAag r r p-value p-value Group 1 (n=60) Group 2 (n=60) Group 3 (n=60)

Statistics Statistical analysis was done by using the Mann-Whitney-Wilcoxon test.

-0.12 0.09 -0.15

0.34 0.46 0.22

0.23 0.08 0.005

0.006 0.49 0.97

Group 1=patients with mechanical heart valve prosthesis. Group 2=patients with coronary artery bypass grafts. Group 3=patients after deep venous thrombosis or pulmonary embolism.

RESULTS In Table 1 the Spearman rank correlations are given between INR and D-dimer and between INR and t-PAag in the three patient groups. A weak correlation (r=0.23; p=O.O06) was only found for t-PAag in the mechanical heart valve group. Table 2 summarises the means and standard deviations for D-dimer, t-PAag, TAT III and F 1+2 in the different patient groups and the group of healthy individuals. The D-dimer values are higher in the patient groups (265, 314 and 346 kg/l, respectively) in comparison with the reference group (238 pg/l). The differences for group 2 and group 3 were statistically significant (p
DISCUSSION Oral anticoagulation with phenprocoumon induces a low protein C activity and one would expect a reduced fibrinolytic activity in blood as a consequence of the upward regulation of the plasminogen activator inhibitor capacity.* The opposite effect has been observed in this study for D-dimer and t-PAag in two of the three investigated groups: in the group with coronary artery bypass grafts and in the patient group under oral anticoagulation after deep venous thrombosis or pulmonary embolism. In all groups however the D-dimer/TAT-III and D-dimer/F 1+2 ratios were grossly enhanced and surprisingly high. Thus the decreased thrombin formation is under oral anticoagulation not paralleled by a lowered fibrinolysis, whereas the D-dimers only can originate from the degradation of cross-linked fibrin. An explanation might be the difference in half-life between D-dimer and the coagulation activation markers, but this seems not to be likely because of the

Table 2 Comparison of the D-dimer, t-PAag, TAT III and F 1+2 results in the different patient groups and the reference group. The differences were statistically tested with the Mann-Whitney-Wilcoxon test. The D-dimer values were statistically significant for group 2 and 3 (p
t-PAag

TAT III

Mean

SD

Mean

SD

Mean (u’l)

SD

Prothrombin fragment 1+2 Mean SD

265

231

6.8

2.2

1.8

0.63

0.19

0.10

314

420

8.6

2.5

1.8

0.61

0.28

0.15

346

409

7.9

2.4

1.5

0.46

0.20

0.09

238

100

6.5

2.8

2.6

0.8

0.77

0.17

thrombosis or pulmonary embolism (INR 4.8-2.1) Group 4 (n-50) Group of healthy individuals

Fibrinolysis Table 3 Comparison of the D-dimer/TAT

II1 and D-dimer/F 1+2 ratios in the different patient groups and the reference group. All D-dimer/TAT-III and D-dimer/F 1+2 ratios were statistically different from the results in the group of healthy individuals (Mann-Whitney-Wilcoxon test), p-values
Patient groups Group 1 (n=60) Patient group with mechanical heart valve (INR 4.8-2.1) Group 2 (n=60) Patient group with coronary artery bypass grafts (INR 4.%1.8) Group 3 (n=60) Patients with deep venous thrombosis or pulmonary embolism (INR 4.s2.1) Group 4 (n=50) Group of healthy individuals

D-dimer/TAT III ratio Mean SD

D-dimer/F 1+2 ratio Mean SD

153

119

44.5

29.2

176

171

40.3

50.0

215

146

48.6

30.0

70

47

9.1

17.3

D-dimer/TAT-III and D-dimer/F 1+2 ratios in the group of healthy individuals. Evidence for an increased fibrinolytic activity under oral anticoagulation has been reported earlier but in few studies it was based upon the enhancement of fibrin(ogen) degradation products* or upon the elevation of tissue plasminogen activator levels.3 In one study’ even under fixed minidose warfarin significantly elevated fibrin specific degradation products could be assessed. The explanation of the enhanced fibrinolytic activity was speculated to be an impairment of tissue plasminogen activator excretion. A comparable phenomenon was observed by Estivals et al’ in patients treated with unfractionated heparin. They observed D-dimer levels clearly above the upper limit of the normal range irrespective of the duration of the anticoagulant treatment. The suggested explanation was that fibrinolysis is a long-lasting process which occurs independently of thrombin generation or heparin therapy. In this study we also could not find a correlation between INR and D-dimer and t-PAag concentrations, possibly because of the small INR range studied (Table 1). The impact of the results in this study is dual. Tissue plasminogen activator promotes platelet disaggregation in high plasma concentrations.‘The question is if the relatively low concentrations of t-PAag as measured during oral anticoagulation might also already have such an effect. Fibrin fragments D possess anticoagulation properties, which should be taken into account for their interference with the normal polymerisation of

low

Received: 31 October 1991 Accepted after revision: 13 February 1992 Offprint orders to: Dr J. W. J. van Wersch, Haematological Laboratory, De Wever Hospital, PO Box 4446,6419 CX Heerlen, The Netherlands.

49

fibrin monomers.’ Fibrin fragments (X, Y, D and E) possess thereby affinity for platelet membranes and coat them with platelet dysfunction as a result.%” They are thought to be responsible to a great extent for the in vivo haemorrhagic state seen in defibrinationI when they are present in high concentrations. The existing risk of a haemorrhage during oral anticoagulation treatment might still be enhanced by the anticoagulation properties of the fibrin degradation products and tissue plasminogen activator. On the other hand accelerated fibrinolysis might be a favourable effect, because it would quickly remove developing thrombi. In summary, the results of this study are indicative for a shift to fibrinolysis in spite of the low coagulation level during oral anticoagulation. This might be a relevant side-effect of oral anticoagulation.

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