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Monitoring of haemostatic parameters during thrombolysis with rtPA for deep venous thrombosis: correlation with clinical events
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Fibrinolysis & Proteolysis (2000) 14 (6), 343–350 © 2000 Harcourt Publishers Ltd doi: 10.1054/fipr.2000.0093, available online at http://www.idealibrary.com on
Monitoring of haemostatic parameters during thrombolysis with rtPA for deep venous thrombosis: correlation with clinical events M. Grünewald,1 M. Griesshammer,1 D. Ellbrück,1 E. Seifried2 1
Department of Medicine, Haemostaseology Division, University of Ulm Institute of Immune-Haematology and Transfusion Medicine, Frankfurt, Germany
2
Summary In a substudy on patients undergoing thrombolytic therapy for deep venous thrombosis with different doses of recombinant tissue-type plasminogen activator (Alteplase; Actilyse®, Boehringer Ingelheim, Germany) within a multicentre trial, several haemostatic parameters were determined serially in an attempt to correlate changes of these parameters with clinical events, such as therapeutic outcome and bleeding complications. The main finding of our study was that the consumption of the inhibitors of fibrinolytic activity, PAI-1 and plasmininhibitor (formerly ␣2-antiplasmin) during continuous thrombolysis for deep venous thrombosis was associated with a significant increase of bleeding complications. In addition we found a trend towards lower recanalization rates and more frequent bleeding complications in patients with enhanced activation of the plasmatic coagulation system, reflected by higher concentrations of the activation peptides thrombin-antithrombin-complex, fibrin(ogen)-degradationproduct and d-dimer. As bleeding represents the major limitation to a wider application of thrombolytic therapy in deep vein thrombosis it might be worthwhile to evaluate a concept of individualized thrombolytic therapy, adjusted for parameters associated with enhanced bleeding risk and low recanalization rates. © 2000 Harcourt Publishers Ltd
INTRODUCTION Theoretically, deep venous thrombosis (DVT) is a logical and therefore attractive target for thrombolytic therapy.1 For a time, evolution of the thrombolytic therapy approach had been rapid, mainly fuelled by the striking success thrombolysis achieved in the acute myocardial infarction (AMI) setting. But whereas thrombolysis for AMI has become a widely accepted therapeutic approach,2,3 thrombolysis has never really become a routine treatment for DVT.4 In AMI it was demonstrated beyond reasonable doubt, that thrombolysis can reduce mortality and morbidity.5 In DVT, mortality, theoretically preventable by thrombolysis, is rare. Received: 30 May 2000 Accepted after revision: 7 September 2000 Correspondence to: Dr Martin Grünewald, Abteilung Innere Medizin III, Sektion Hämostaseologie, Klinik und Poliklinik der Universität Ulm, Robert-Koch-Strasse 8, D 89081 Ulm, Germany. e-mail: [email protected]
Morbidity is mainly due to recurrent thromboembolism (17.5% at 2 years, 30.3% at 8 years) and/or postthrombotic changes (22.8% at 2 years, 29.1% at 8 years).6 Whether thrombolysis can prevent the substantial and severe morbidity7 by prevention of postthrombotic sequelae is still under debate.1,8 It has been demonstrated clearly, however, that early reperfusion rates in DVT are 3–10 times8–10 higher after thrombolysis when compared to heparin alone.11,12 The early restoration of patency is strongly related to decreased rates of popliteal reflux during a 5–10 year follow-up (77% reflux without vs 9% with complete lysis).4 It is obvious that for the preservation of venous valvular function, and hereby for the prevention of postthrombotic syndromes, the removal of the source of destructive inflammation, the thrombus, is critical.13 Thus any therapeutic approach combining high early reperfusion rates with preserved safety should be considered carefully for the treatment of DVT. The feasibility of continuous thrombolysis with intravenously administered rtPA was evaluated for 343
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different dosages in a randomized multi-centre trial (data not published); on a subset of 26 patients included in this trial, we performed extensive coagulation analyses with the intention to correlate these results with clinical events. MATERIALS AND METHODS Patient population Patients with phlebographically confirmed first deep vein thrombosis, symptomatic for 14 days, between 18 and 60 years of age and of more than 50 kg body weight, were asked to participate in the study. They were included if they gave written or witnessed informed consent and did not present any of the following contraindications: Prior deep vein thrombosis, severe medical illness, cardiac arrhythmia, prior thrombolytic therapy or any contraindication to thrombolytic therapy. Treatment protocol The main study was a multi-centre, open, randomized study of consecutive patients presenting with the above named inclusion criteria; the treatment protocol was approved by the local ethics committees. Our study group consisted of all patients included in the study at the Medical Department of the University of Ulm. After inclusion all patients were immobilized, the thrombosed leg or arm was bandaged and a compression stocking was put on the other leg or on both legs in case of arm vein thrombosis. All patients received unfractionated heparin intravenously at a dose to prolong the aPTT 2fold. Continuous, intravenous thrombolytic therapy with recombinant tissue-type plasminogen activator (rtPA) (Actilyse®, Boehringer Ingelheim, Germany) was administered at 0.75, 0.5, 0.375 or 0.25 mg per kg bodyweight per day (d) according to the randomly allocated treatment group. Phlebographic evaluation of the initially thrombosed veins was performed on day 4 and/or 7; if complete recanalization was achieved by day 4 no further thrombolytic therapy was administered; treatment was individualized in any case after day 7. Evaluation of phlebograms was performed centrally by an investigator blinded for the treatment; results are presented as Marder scores.14 On the basis of colour-coded duplex-sonographic assessment, results were classified as complete recanalization of all formerly thrombosed veins, good partial recanalization (50%, haemodynamically sufficient flow), moderate partial recanalization (50%, haemodynamically insufficient flow), thrombus reduction (without flow) and no change. Therapeutic success was defined as complete recanalization or partial recanalization with haemodynamically sufficient flow.
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The inclusion of the latter group may be debateable; we think, however, that the restoration of haemodynamically sufficient flow early in the course of thrombotic disease is preventative of postthrombotic disease under continued oral anticoagulation. Safety procedures included close clinical surveillance on the intensive care unit and frequent control of hematocrit and coagulation parameters. In case of a major bleeding complication, defined as a fall in haematocrit of more than 10%, bleeding necessitating blood transfusion or surgery, retroperitoneal or intracerebral bleeding, thrombolytic therapy was terminated immediately. Blood sampling and analysis aPTT, TT and fibrinogen were determined twice daily; for our extended coagulation studies, blood samples were obtained 4–6 h after start of thrombolytic therapy, at days 3 and 5, at the end of therapy and 12–36 h after the end of therapy. Blood samples were drawn from a large antecubital vein of the arm contralateral to the infusion arm. In arm vein thrombosis rtPA was infused in a distal vein of the thrombosed arm. Every first 2 ml of blood were discarded; 9 ml of blood were drawn on 1 ml of citrate (final concentration 11 mM); samples were centrifuged, aliquoted and snap frozen at 970°C until further processing. rtPA-antigen was measured with a special ELISA.15 We chose the determination of rtPA-antigen instead of rtPAactivity, as the antigen determination more correctly reflects the total presence of rtPA in plasma, including free and complexed forms. This was thought necessary for the correlation analysis with the infused amount of rtPA. Plasminogen, plasmin-inhibitor (formerly ␣2antiplasmin) and PAI-1-activity were determined spectrophotometrically with the chromogenic substrates S 2251 or S 2403 (KABI Diagnostika, Mölndal, Sweden). Fibrinogen concentrations were determined by a clotting rate method (Immuno GmbH, Heidelberg, Germany), modified from the original Clauss method.16 TDP-, FbDP-, FgDP-, d-dimer- and TAT-concentrations were determined using commercially available ELISA-kits (Boehringer Mannheim GmbH, Mannheim, Organon Teknika, Eppelheim, Behringwerke AG, Marburg, Germany). Statistical comparisons between patient subgroups were performed with the Mann–Whitney two-sample test for non-matched pairs, comparisons within or between cycles with the Mann–Whitney two-sample test for matched pairs; the null-hypothesis was rejected if the significance level was 5% (P0.05); all results are expressed as medians and 25th–75th percentile range. Linear regression analysis was performed to detect a correlation between parameters.
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RESULTS Patient characteristics A total of 26 patients were included during the study period: 13/26 patients were male; median age was 41 years (range 18–58); median weight was 75 kg (range 52–110); median height was 173 cm (range 157–192); 23/26 patients had leg-vein thrombosis (8 right, 15 left); the remaining three had arm-vein thrombosis (2 right, 1 left). Coagulation parameters
aPTT and fibrinogen Therapeutic heparinization, randomly defined as an aPTT 1.5the normal upper range at 50% of observations, was achieved in only 35% of patients; no correlation of median aPTT values with a favourable therapeutic outcome or bleeding complications was found (Fig. 1A). Fibrinogen concentrations were insignificantly lower in the 0.25 mg/kg/d-dosage-groups compared to the 0.25 mg/ kg/d-group. Fibrinogen concentrations in patients with and without bleeding events (370 vs 289 mg/dl; P:0.06 for maximum difference (day 4), or with and without therapeutic success (411 vs 310 mg/dl; P:0.11 for maximum difference (day 6) (Fig. 1B) were comparable. rtPA-antigen rtPA-antigen concentrations were elevated significantly over pre-treatment values in all patient groups at all sampling instants (Table 1). No correlation was found between administered dose and median rtPA-antigen levels; on day 3 median rtPA-antigen levels were 57.9, 45.9, 64.4 and 40.7 ng/ml in the 0.75, 0.5, 0.375 and 0.25 mg/kg/ d-dosage-groups respectively. The respective values for day 5 were 106.7, 36.4, 38.4 and 61.9 ng/ml. At the end of therapy 58.0, 32.1, 43.5 and 46.2 ng/ml of rtPA-antigen were found in the respective treatment groups. Median rtPA-antigen concentrations were similar in patients with and without bleedings or with and without therapeutic success. No correlation was found between rtPA-antigen Table 1
and PAI-1-activities (day 3, R2:0.019/day 5, R2:0.021) or plasmin-inhibitor-activities on day 3 (R2:0.008); a correlation of borderline significance was found on day 5 (R2:0.32, P:0.045). No correlation was found with any of the activation markers.
Activation markers: TAT, TDP, FgDP, FbDP and d-dimer The concentrations of total-degradation-products (TDP), fibrin-degradation-products (FbDP) and d-dimers were elevated significantly over pre-treatment values at day 3 in all patient groups, for thrombin-antithrombincomplexes (TAT) and fibrinogen-degradation-products (FgDP) only borderline changes were noted (Table 2, Fig. 2). On day 5 no significant changes in relation to pre-treatment results were seen for either parameter in any patient group. TAT, TDP, FbDP and d-dimer results
Fig. 1 (A & B) aPTT- and fibrinogen-values during continuous thrombolytic therapy for DVT in patient groups with different clinical outcomes.
rtPA antigen levels in patient groups with different clinical outcomes
Parameter
rtPA antigen (ng/ml)
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Day 3
All patients Bleed No bleed Success No success
n1
Median
Range2
18 6 12 7 11
44.3 53.1 41.2 58 41.2
37.4–59.5 45.1–59.5 36.9–60.5 46.7–102.3 36.9–60.5
Day 5
P value3
0.39 0.25
To base4
n1
Median
Range2
P0.0001 P:0.004 P:0.0001 P:0.003 P:0.0001
13 3 10 5 8
39 53.3 36.2 84.7 37.5
33.6–58.2 49.8–144.4 27.6–58.2 36.4–106.7 30.6–51.6
P value3
To base4
0.12
P0.0001 P:0.02 P:0.0002 P:0.006 P:0.0005
0.18
1
number of patients; 225th–75th percentile; 3for comparison between subgroups; 4comparison to baseline test result; rtPA, recombinant tissue-type plasminogen activator.
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Table 2
Activation markers in patient groups with different clinical outcomes
Parameter
Day 3
n1 TAT concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 TDP concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 FgDP concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 FbDP concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 d-dimer concentration (ng/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15
Day 5
Median
Range2
P value3
17.3 20.6 16.1 9.3 30.1
9–39 9.3–42.2 8.8–38.9 8.9–18.5 12.4–39.3
0.45
8 22.6 6.3 3.9 12.8
3.9–33 3.8–47.5 3.9–32.6 2.8–22.6 4.9–47.5
1 2.2 0.8 1 1
0.7–4.5 1–4.8 0.5–1.9 0.6–4.2 0.8–6.3
4.5 7.5 4.1 2.5 7.1
2.5–24.7 2.5–35.4 2.4–24.1 1.8–7.5 4.1–35.4
0.43
4.5 5.4 4.3 3 8.4
2.4–16.3 3–30.3 2.3–13 1.8–3.3 3.3–27.3
0.43
0.11
0.35 0.09
0.07 0.61
0.09
0.07
To base4
n1
Median
Range2
P:0.22 P:0.90 P:0.10 P:0.93 P:0.10
19 5 14 7 12
23.5 23.5 22 11.8 25.7
8.7–37.7 10.1–23.9 8.7–37.7 5.6–46.2 11.2–34
P:0.0008 P:0.01 P:0.05 P:0.01 P:0.01
18 4 14 6 12
5.7 18 5.3 4.7 11.6
2–14.7 3.8–35.4 2–13 2–5.6 2.4–19.8
P:0.06 P:0.05 P:0.46 P:0.33 P:0.08
19 5 14 7 12
0.8 8 0.6 0.7 0.8
0.5–1.8 1.3–7.8 0.4–1.4 0.4–1.8 0.5–2.6
P:0.001 P:0.01 P:0.04 P:0.02 P:0.008
18 4 14 6 12
3.5 8.7 3.5 2.1 8.7
1.2–10.8 1.3–20.4 1.2–10.2 1.2–2.8 1.4–13.8
P:0.003 P:0.01 P:0.09 P:0.02 P:0.02
18 4 14 6 12
3.5 9.6 3.5 1.8 9.1
1.5–10 1.5–20 1.5–9.8 1.5–3.2 1.6–11.8
P value3
To base4
0.78
P:0.39 P:0.54 P:0.10 P:0.87 P:0.31
0.67
0.26 0.13
0.04 0.61
0.67 0.13
0.42 0.10
P:0.07 P:0.06 P:0.26 P:0.13 P:0.10 P:0.6 P:0.14 P:0.66 P:0.96 P:0.53 P:0.10 P:0.26 P:0.32 P:0.19 P:0.10 P:0.16 P:0.29 P:0.37 P:0.48 P:0.15
1
number of patients; 225th–75th percentile; 3for comparison between subgroups; 4comparison to baseline test result; TAT, thrombinantithrombin-complex; TDP, total-degradation-products; FgDP, fibrinogen-degradation-products; FbDP, fibrin-degradation-products.
were comparable for patients with and without bleedings. FgDP concentrations were elevated in patients with bleedings with the differences to patients without bleeding reaching borderline significance. All markers of coagulation activation were similar in patients with and without recanalization. A correlation was seen between TDP and TAT (day 3, R2:0.58/day 5, R2:0.26), FgDP (0.83/0.60), FbDP (0.96/0.96) or d-dimer (0.67/0.83). No correlation was found between any of the activation markers and plasmin-inhibitor- or PAI-1-activities.
Plasminogen, plasmin-inhibitor (formerly ␣2-antiplasmin) and PAI-1 Activities of plasmin-inhibitor, plasminogen-activatorinhibitor 1 (PAI-1) and plasminogen were decreased significantly in all patient groups on day 3 compared to baseline values (Table 3, Fig. 3). On day 5 the significant decrease persisted in all patient groups for plasmininhibitor and PAI-1 activity, for plasminogen a persistant, significant decrease was noted only in the overall patient group and for patients with bleedings or therapeutic Fibrinolysis & Proteolysis (2000) 14(6), 343–350
success. Patients with and without recanalization showed comparable plasminogen, plasmin-inhibitor and PAI-1 activities. Plasminogen activities in patients with bleeding were insignificantly lower compared to patients without bleeding. Plasmin-inhibitor and PAI-1 activities were significantly lower in patients with bleedings in comparison to those without. Clinical, safety and patency data Median number of treatment days was 6.19 (range 1.95–14.25). Treatment was terminated early because of bleeding events in 10/26 patients (0.75 mg: 4/5 patients; 0.5 mg: 4/8 patients; 0.375 mg: 2/7 patients; 0.25 mg: 0/6 patients). Detailed analysis of major bleedings in the 0.75 mg-group revealed one retroperitoneal bleeding on day 3, two cases of gross macrohaematuria on days 3 and 4 and one extensive puncture-site bleeding involving the arm on day 2; in the 0.5 mg-group there were two retroperitoneal bleedings on days 4 and 6, one intraabdominal bleeding on day 3 and one incidence of © 2000 Harcourt Publishers Ltd
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A
C
B
D
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Fig. 2 (A–D) Concentrations of fibrinogen-degradation-products (FgDP), fibrin-degradation-products (FbDP), thrombin-antithrombincomplexes (TAT) and d-dimers during continuous thrombolytic therapy for DVT in patient groups with different clinical outcomes. Results are depicted on a logarithmic scale and presented as means with 25th–75th percentile range (bars).
Table 3
Plasmin-inhibitor-, PAI-1- and plasminogen activities in patient groups with different clinical outcomes
Parameter
Day 3
n1 Plasmin-inhibitor activity (%) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 PAI-1 activity (AU/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 Plasminogen activity (%) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15
Median 75 53 81 79 73 5.5 0 11 7 4 104 97 109 98 105
Range2 55.5–85 51–57 77–89 57–81 53–89
Day 5
P value3
To base4
n1
Median
Range2
0.0002
P0.0001 P:0.0002 P:0.0007 P:0.0003 P:0.0002
19 5 14 7 12
77 35 80.5 79 72.5
64–84 27–65 68–87 60–84 64.5–85.5
P:0.0001 P:0.003 P:0.01 P:0.002 P:0.01
19 5 14 7 12
2 0 5 5 2
P:0.009 P:0.0005 P:0.49 P:0.04 P:0.09
18 4 14 6 12
112.5 101.5 114.5 100 114.5
0.86
0–11.5 0–0 4–15 0–12 0–11
0.01
94.5–120 83–104 96–130 88–109 95–126
0.03
0.93
0.29
0–16 0–0 0–17 0–16 0–12.5 93–119 86–112.5 97–119 89–111 97.5–124.5
P value3
0.02 0.77
0.009 0.87
0.18 0.11
To base4
P0.0001 P:0.002 P:0.0004 P:0.001 P:0.0003 P:0.0003 P:0.004 P:0.01 P:0.007 P:0.01 P:0.03 P:0.02 P:0.31 P:0.03 P:0.23
1
number of patients; 225th–75th percentile; 3for comparison between subgroups; 4comparison to baseline test result; PAI-1, plasminogen activator inhibitor 1.
prolonged macrohaematuria on day 6; in the 0.375 mggroup there were two incidences of severe macrohaematuria on days 6 and 7. No other side-effects attributable to thrombolytic treatment were noted. All patients made © 2000 Harcourt Publishers Ltd
a full recovery and were discharged from hospital receiving long-time oral anticoagulant treatment. Complete or good partial recanalization was achieved in 9/26 patients (0.75 mg: 3/5 patients; 0.5 mg: 3/8 patients; Fibrinolysis & Proteolysis (2000) 14(6), 343–350
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Fig. 3 (A & B) Plasmin-inhibitor- and PAI-1-activities during continuous thrombolytic therapy for DVT in patient groups with different clinical outcomes. Results are depicted on a linear scale and presented as means with 25th–75th percentile range (bars).
0.375 mg: 1/7 patients; 0.25 mg: 2/6 patients), moderate partial recanalization or thrombus reduction was seen in an additional 3/26 patients (all in the 0.375 mg group). Phlebograms allowing detailed evaluation could be obtained in 16/26 patients. Marder score decreased from 25.5 to 22 in the overall study group (0.75 mg: 20–18; 0.5 mg: 26.75–21; 0.375 mg: 23–18.7; 0.25 mg: 28.7–26.1). DISCUSSION Analyses of the coagulation system In numerous studies it has been tried to correlate the bleeding risk with changes of haemostatic variables; in accordance with previous reports, we found no significant difference of fibrinogen levels in patients with vs without bleeding complications. Fibrinogen levels were at all times above the lower limit of the normal range17 (Fig. 1B). The measurement of fibrin(ogen) degradation products (FDP) is of special interest in the context of bleeding for two reasons. FDPs interfere with clot formation and lead to the formation of instable clots highly susceptible to lysis and high FDP concentrations, especially high FgDP concentrations, may be indicative of (uncontrolled) systemic plasmin-activity.18 In theory therefore, high FDP concentrations should be associated with an increased bleeding tendency, and indeed we did find a trend towards higher concentrations of TAT, TDP, Fibrinolysis & Proteolysis (2000) 14(6), 343–350
FbDP, FgDP and d-dimer in patients with bleedings, with the differences reaching borderline significance for FgDP, an observation which has also been made in the setting of thrombolysis for AMI19 (Fig. 2). Control of plasminogen-activator induced and plasmin-mediated fibrinolysis is maintained mainly through PAI-1- and plasmininhibitor-activity. During short-term thrombolysis for AMI a (near) total consumption of these inhibitors with prompt rebound supra-normal elevation is found.20,21 No correlation with bleeding events could be demonstrated in these studies. During continuous thrombolysis for DVT we saw a progressive decline in PAI-1- and plasmininhibitor-activities in the overall group with significantly lower values in patients with bleeding complications as compared to patients without bleedings (Fig. 3). We conclude that control of systemic plasmin activity is a main determinant of bleeding complications during continuous thrombolytic therapy. On the basis of these findings we hypothesize, that serial measurements of PAI-1- and plasmin-inhibitor-activities could increase the safety of long-term thrombolysis. The number of patients investigated in our study, however, was too small to draw reliable conclusions. Our preliminary findings need to be confirmed in larger, prospective trials. Moreover, it remains unclear, whether or not the determination of PAI-1 and plasmin-inhibitor activities represent the most suitable markers for an enhanced bleeding risk under continuous thrombolytic therapy with rtPA. In the early days of therapeutic fibrinolysis it has been claimed, that for the achievement of thrombolysis a ‘lytic state’ with near-total consumption of fibrinogen is necessary.22 Since then it was shown in various studies, that no correlation exists between fibrinogen activity and thrombolytic efficacy.17 These findings are once again confirmed for continuous thrombolysis for DVT. Trials of thrombolytic therapy for AMI tried to establish a correlation between rtPA levels and success rates; however, a clear correlation could never be documented.19 In accordance with these findings, we did not find different rtPA-antigen concentrations in patients with or without therapeutic success in our study. Moreover, we did not find a clear correlation between the rtPA dose administered and rtPA antigen plasma levels. This finding is probably mostly due to individually heterogeneous rtPA metabolism, including different rates of rtPA complex formation, mainly with PAI-1, and clearance. In addition we found no correlation of rtPA antigen with PAI-1 or plasmin-inhibitor activities or any of the activation markers. Thus in our experience there is no marker to predict or monitor an rtPA effect. Enhanced concentrations of markers of thrombin-generation (prothrombin fragments 1;2) and/or thrombin-activity (TAT) indicate a shift of the coagulation balance towards enhanced procoagulant activity and elevated concentrations of © 2000 Harcourt Publishers Ltd
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FDPs (TDP, FbDP, FgDP and d-dimers) are markers of an activated coagulation system.23,24 Coagulation activation and enhanced procoagulant activity are associated with resistance to thrombolytic therapy and rethrombosis.17,25,26 In keeping with this, we found higher TAT, TDP, FbDP and d-dimer concentrations in patients without therapeutic success when compared to patients with reperfusion; however these differences were not statistically significant (Fig. 2). Clinical data The overall bleeding rates observed in our study are comparable to those reported from other studies varying from 13 to 57%, with major bleedings being reported from 2.2 to 27% (overview in Grohmann et al.27). Recanalization rates in our substudy were comparable to recanalization rates from other studies on systemic thrombolysis in DVT, ranging from 28 to 80% (overview in Grohmann et al.27). Whether a substantial improvement of recanalization rates is achievable with locoregional thrombolysis and/or with more effective anticoagulation, e.g. with hirudin, is still a matter of debate and ongoing investigations. It is noteworthy that in our small and, theoretically, well-monitored group of patients, satisfactory prolongation of aPTT under therapy with unfractionated heparin was achieved in only 35% of patients, very probably contributing to the disappointingly low reperfusion rates. A clear trend towards higher bleeding (8/13) and higher success rates (6/13) was evident in the two groups receiving the higher rtPA doses (0.75 and 0.5 mg/kg/d) compared to the two lower dose groups (2/13 and 3/13). Thus the dosage regimen with optimal efficacy and safety remains unknown. We feel, however, that rtPA doses exceeding 0.5 mg/kg/d should not be used for continuous thrombolysis in DVT. CONCLUSION Based upon our findings of significantly lower activities of PAI-1 and plasmin-inhibitor in patients with bleeding complications it is hypothesized that (uncontrolled) systemic plasmin activity confers an increased risk of bleeding complications during continuous thrombolysis with rtPA for DVT. Repeated control of these parameters and adjustment of the treatment according to the results may increase the safety of thrombolysis in this setting. Elevated concentrations of FDPs are indicators of insufficient control of thrombin activation and formation, leading to resistance to thrombolysis and/or rethrombosis; whether more effective anticoagulants, such as hirudin, could improve further the results of thrombolytic therapy in DVT remains speculative and requires further investigation. High patency rates have been reported from © 2000 Harcourt Publishers Ltd
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studies investigating catheter-directed, regional thrombolysis for DVT. In addition, relatively low rates of bleeding complications have been observed.28,29 These encouraging results warrant extended investigation, as thrombolytic treatment of venous thromboembolism is still underused.4 A combined approach of ‘high-performance thrombolysis’, together with a closely monitored haemostatic system to prevent bleeding complications, may facilitate a more extensive use of thrombolysis for venous thromboembolism and hereby prevent substantial long-term morbidity.
ACKNOWLEDGEMENTS The authors are indebted to the teams of the coagulation laboratory and the intensive care unit at the University Hospital of Ulm for their excellent cooperation. The assistance of Dr A. Riedel, Boehringer Ingelheim Pharma KG, in the preparation of the manuscript is appreciated. The multi-centre trial was supported by the former Dr Karl Thomae GmbH, now Boehringer Ingelheim Pharma KG, Biberach, Germany. REFERENCES 1. Goldhaber SZ. Thrombolytic therapy. Adv Int Med 1999; 44: 311–325. 2. Grünewald M, Seifried E. Meta-analysis of all available published clinical trials (1958–1990) on thrombolytic therapy for AMI: relative efficacy of different therapeutic strategies. Fibrinolysis 1994; 8: 67–86. 3. Ludlam CA, Bennett B, Fox KAA, Lowe GDO, Reid AW. Guidelines for the use of thrombolytic therapy. Blood Coag Fibrinol 1995; 6: 273–285. 4. Sasahara A. Venous thromboembolic disease: who should receive thrombolytic treatment? Plenary lecture at the XVIIth Congress of the International Society on Thrombosis and Haemostasis, Washington, July 1999. 5. Indications for fibrinolytic therapy in suspected acute myocardial infarction: collaborative overview of early mortality and major morbidity results from all randomised trials of more than 1000 patients. Fibrinolytic Therapy Trialists’ (FTT) Collaborative Group. Lancet 1994; 343: 311–322. 6. Prandoni P, Lensing AW, Cogo A et al. The long-term clinical course of acute deep venous thrombosis. Ann Intern Med 1996; 125: 1–7. 7. Carter CJ. The natural history and epidemiology of venous thrombosis. Prog Cardiovasc Dis 1994; 36: 423–438. 8. Ng CM, Rivera JO. Meta-analysis of streptokinase and heparin in deep vein thrombosis. Am J Health Syst Pharm 1998; 55: 1995–2001. 9. Weinmann EE, Salzman EW. Deep-vein thrombosis. N Engl J Med 1994; 331: 1630–1641. 10. Comerota AJ, Aldridge SC. Thrombolytic therapy for deep venous thrombosis: a clinical review. Can J Surg 1993; 36: 359–364. 11. Rogers LQ , Lutcher CL. Streptokinase therapy for deep vein thrombosis: a comprehensive review of the English literature. Am J Med 1990; 88: 389–395.
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12. Bounameaux H. Thrombolytic therapy: can it prevent the development of post-thrombotic syndrome? Fibrinol Proteol 1998; 12 (suppl. 2): 31–37. 13. Cho J, Martelli E, Mozes G, Miller VM, Gloviczki P. Effects of thrombolysis and venous thrombectomy on valvular competence, thrombogenicity, venous wall morphology, and function. J Vasc Surg 1998; 28: 787–799. 14. Marder VJ, Soulen RL, Atichartkan V et al. Quantitative venographic assessment of deep vein thrombosis in the evaluation of streptokinase and heparin therapy. J Lab Clin Med 1977; 89: 1018–1029. 15. Nilsson K, Rosén S, Friberger P. A new kit for the determination of tissue plasminogen activator and its inhibitor in blood. Fibrinolysis 1987; 1: 163–168. 16. Clauss A. Gerinnungsphysiologische Schnellmethode zur Bestimmung des Fibrinogens. Acta Haematol 1957; 17: 237–246. 17. Grünewald M, Seifried E. Laboratory monitoring during thrombolytic therapy in clinical practice and research. Z Kardiol 1993; 82 (Suppl. 2): 129–135. 18. Arnold A, Brower R, Collen D et al. Increased serum levels of fibrinogen degradation products due to treatment with recombinant tissue-type plasminogen activator for acute myocardial infarction are related to bleeding complications, but not to coronary patency. JACC 1989; 14: 581–588. 19. Stump DC, Califf RM, Topol EJ et al. Pharmacodynamics of thrombolysis with recombinant tissue-type plasminogen activator. Correlation with characteristics of and clinical outcomes in patients with acute myocardial infarction. Circulation 1989; 80: 1222–1230. 20. Grünewald M, Müller M, Ellbrück D et al. Double- versus single-bolus thrombolysis with reteplase for acute myocardial infarction: a pharmacokinetic and pharmacodynamic study. Fibrinol Proteol 1997; 11: 137–145.
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21. Sane DC, Stump DC, Topol EJ et al. Correlation between baseline plasminogen activator inhibitor levels and clinical outcome during therapy with tissue plasminogen activator for acute myocardial infarction. Thromb Haemost 1991; 65: 275–279. 22. Fletcher AP, Alkjaersig N, Sherry S. The maintenace of a sustained thrombolytic state in man. I. Induction and effects. J Clin Invest 1959; 38: 1096–1110. 23. Bauer KA, Rosenberg RD. The pathophysiology of the prethrombotic state in humans: insights gained from studies using markers of hemostatic system activation. Blood 1987; 70: 343–350. 24. Lip GYH, Lowe GDO. Fibrin d-dimer: a useful clinical marker of thrombogenesis? Clin Sci 1995; 89: 205–214. 25. Gulba DC, Barthels M, Westhoff-Bleck M et al. Increased thrombin levels during thrombolytic therapy in acute myocardial infarction. Relevance for the success of therapy. Circulation 1991; 83: 937–944. 26. Merlini PA, Ardissino D. Current status of activation markers in ischemic heart diesease: markers of coagulation activation. Thromb Haemost 1997; 78: 276–279. 27. Grohmann G, Kaufmann U, Lindloh C et al. Untersuchungen zur niedrig dosierten lokoregionalen Thrombolysetherapie von isolierten Beinvenenthrombosen mit Actilyse (rt-PA). Teil I: Die Effektivität der Thrombolyse. Perfusion 1998; 11: 220–231. 28. Semba CP, Dake MD. Iliofemoral deep venous thrombosis: aggressive therapy with catheter-directed thrombolysis. Radiology 1994; 191: 487–494. 29. Mewissen MW, Seabrook GR, Meissner MH, Cynamon J, Labropoulos N, Haughton SH. Catheter-directed thrombolysis for lower extremity deep venous thrombosis: report of a national multicenter registry. Radiology 1999; 211: 39–49.
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Monitoring of haemostatic parameters during thrombolysis with rtPA for deep venous thrombosis: correlation with clinical events M. Grünewald,1 M. Griesshammer,1 D. Ellbrück,1 E. Seifried2 1
Department of Medicine, Haemostaseology Division, University of Ulm Institute of Immune-Haematology and Transfusion Medicine, Frankfurt, Germany
2
Summary In a substudy on patients undergoing thrombolytic therapy for deep venous thrombosis with different doses of recombinant tissue-type plasminogen activator (Alteplase; Actilyse®, Boehringer Ingelheim, Germany) within a multicentre trial, several haemostatic parameters were determined serially in an attempt to correlate changes of these parameters with clinical events, such as therapeutic outcome and bleeding complications. The main finding of our study was that the consumption of the inhibitors of fibrinolytic activity, PAI-1 and plasmininhibitor (formerly ␣2-antiplasmin) during continuous thrombolysis for deep venous thrombosis was associated with a significant increase of bleeding complications. In addition we found a trend towards lower recanalization rates and more frequent bleeding complications in patients with enhanced activation of the plasmatic coagulation system, reflected by higher concentrations of the activation peptides thrombin-antithrombin-complex, fibrin(ogen)-degradationproduct and d-dimer. As bleeding represents the major limitation to a wider application of thrombolytic therapy in deep vein thrombosis it might be worthwhile to evaluate a concept of individualized thrombolytic therapy, adjusted for parameters associated with enhanced bleeding risk and low recanalization rates. © 2000 Harcourt Publishers Ltd
INTRODUCTION Theoretically, deep venous thrombosis (DVT) is a logical and therefore attractive target for thrombolytic therapy.1 For a time, evolution of the thrombolytic therapy approach had been rapid, mainly fuelled by the striking success thrombolysis achieved in the acute myocardial infarction (AMI) setting. But whereas thrombolysis for AMI has become a widely accepted therapeutic approach,2,3 thrombolysis has never really become a routine treatment for DVT.4 In AMI it was demonstrated beyond reasonable doubt, that thrombolysis can reduce mortality and morbidity.5 In DVT, mortality, theoretically preventable by thrombolysis, is rare. Received: 30 May 2000 Accepted after revision: 7 September 2000 Correspondence to: Dr Martin Grünewald, Abteilung Innere Medizin III, Sektion Hämostaseologie, Klinik und Poliklinik der Universität Ulm, Robert-Koch-Strasse 8, D 89081 Ulm, Germany. e-mail: [email protected]
Morbidity is mainly due to recurrent thromboembolism (17.5% at 2 years, 30.3% at 8 years) and/or postthrombotic changes (22.8% at 2 years, 29.1% at 8 years).6 Whether thrombolysis can prevent the substantial and severe morbidity7 by prevention of postthrombotic sequelae is still under debate.1,8 It has been demonstrated clearly, however, that early reperfusion rates in DVT are 3–10 times8–10 higher after thrombolysis when compared to heparin alone.11,12 The early restoration of patency is strongly related to decreased rates of popliteal reflux during a 5–10 year follow-up (77% reflux without vs 9% with complete lysis).4 It is obvious that for the preservation of venous valvular function, and hereby for the prevention of postthrombotic syndromes, the removal of the source of destructive inflammation, the thrombus, is critical.13 Thus any therapeutic approach combining high early reperfusion rates with preserved safety should be considered carefully for the treatment of DVT. The feasibility of continuous thrombolysis with intravenously administered rtPA was evaluated for 343
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different dosages in a randomized multi-centre trial (data not published); on a subset of 26 patients included in this trial, we performed extensive coagulation analyses with the intention to correlate these results with clinical events. MATERIALS AND METHODS Patient population Patients with phlebographically confirmed first deep vein thrombosis, symptomatic for 14 days, between 18 and 60 years of age and of more than 50 kg body weight, were asked to participate in the study. They were included if they gave written or witnessed informed consent and did not present any of the following contraindications: Prior deep vein thrombosis, severe medical illness, cardiac arrhythmia, prior thrombolytic therapy or any contraindication to thrombolytic therapy. Treatment protocol The main study was a multi-centre, open, randomized study of consecutive patients presenting with the above named inclusion criteria; the treatment protocol was approved by the local ethics committees. Our study group consisted of all patients included in the study at the Medical Department of the University of Ulm. After inclusion all patients were immobilized, the thrombosed leg or arm was bandaged and a compression stocking was put on the other leg or on both legs in case of arm vein thrombosis. All patients received unfractionated heparin intravenously at a dose to prolong the aPTT 2fold. Continuous, intravenous thrombolytic therapy with recombinant tissue-type plasminogen activator (rtPA) (Actilyse®, Boehringer Ingelheim, Germany) was administered at 0.75, 0.5, 0.375 or 0.25 mg per kg bodyweight per day (d) according to the randomly allocated treatment group. Phlebographic evaluation of the initially thrombosed veins was performed on day 4 and/or 7; if complete recanalization was achieved by day 4 no further thrombolytic therapy was administered; treatment was individualized in any case after day 7. Evaluation of phlebograms was performed centrally by an investigator blinded for the treatment; results are presented as Marder scores.14 On the basis of colour-coded duplex-sonographic assessment, results were classified as complete recanalization of all formerly thrombosed veins, good partial recanalization (50%, haemodynamically sufficient flow), moderate partial recanalization (50%, haemodynamically insufficient flow), thrombus reduction (without flow) and no change. Therapeutic success was defined as complete recanalization or partial recanalization with haemodynamically sufficient flow.
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The inclusion of the latter group may be debateable; we think, however, that the restoration of haemodynamically sufficient flow early in the course of thrombotic disease is preventative of postthrombotic disease under continued oral anticoagulation. Safety procedures included close clinical surveillance on the intensive care unit and frequent control of hematocrit and coagulation parameters. In case of a major bleeding complication, defined as a fall in haematocrit of more than 10%, bleeding necessitating blood transfusion or surgery, retroperitoneal or intracerebral bleeding, thrombolytic therapy was terminated immediately. Blood sampling and analysis aPTT, TT and fibrinogen were determined twice daily; for our extended coagulation studies, blood samples were obtained 4–6 h after start of thrombolytic therapy, at days 3 and 5, at the end of therapy and 12–36 h after the end of therapy. Blood samples were drawn from a large antecubital vein of the arm contralateral to the infusion arm. In arm vein thrombosis rtPA was infused in a distal vein of the thrombosed arm. Every first 2 ml of blood were discarded; 9 ml of blood were drawn on 1 ml of citrate (final concentration 11 mM); samples were centrifuged, aliquoted and snap frozen at 970°C until further processing. rtPA-antigen was measured with a special ELISA.15 We chose the determination of rtPA-antigen instead of rtPAactivity, as the antigen determination more correctly reflects the total presence of rtPA in plasma, including free and complexed forms. This was thought necessary for the correlation analysis with the infused amount of rtPA. Plasminogen, plasmin-inhibitor (formerly ␣2antiplasmin) and PAI-1-activity were determined spectrophotometrically with the chromogenic substrates S 2251 or S 2403 (KABI Diagnostika, Mölndal, Sweden). Fibrinogen concentrations were determined by a clotting rate method (Immuno GmbH, Heidelberg, Germany), modified from the original Clauss method.16 TDP-, FbDP-, FgDP-, d-dimer- and TAT-concentrations were determined using commercially available ELISA-kits (Boehringer Mannheim GmbH, Mannheim, Organon Teknika, Eppelheim, Behringwerke AG, Marburg, Germany). Statistical comparisons between patient subgroups were performed with the Mann–Whitney two-sample test for non-matched pairs, comparisons within or between cycles with the Mann–Whitney two-sample test for matched pairs; the null-hypothesis was rejected if the significance level was 5% (P0.05); all results are expressed as medians and 25th–75th percentile range. Linear regression analysis was performed to detect a correlation between parameters.
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RESULTS Patient characteristics A total of 26 patients were included during the study period: 13/26 patients were male; median age was 41 years (range 18–58); median weight was 75 kg (range 52–110); median height was 173 cm (range 157–192); 23/26 patients had leg-vein thrombosis (8 right, 15 left); the remaining three had arm-vein thrombosis (2 right, 1 left). Coagulation parameters
aPTT and fibrinogen Therapeutic heparinization, randomly defined as an aPTT 1.5the normal upper range at 50% of observations, was achieved in only 35% of patients; no correlation of median aPTT values with a favourable therapeutic outcome or bleeding complications was found (Fig. 1A). Fibrinogen concentrations were insignificantly lower in the 0.25 mg/kg/d-dosage-groups compared to the 0.25 mg/ kg/d-group. Fibrinogen concentrations in patients with and without bleeding events (370 vs 289 mg/dl; P:0.06 for maximum difference (day 4), or with and without therapeutic success (411 vs 310 mg/dl; P:0.11 for maximum difference (day 6) (Fig. 1B) were comparable. rtPA-antigen rtPA-antigen concentrations were elevated significantly over pre-treatment values in all patient groups at all sampling instants (Table 1). No correlation was found between administered dose and median rtPA-antigen levels; on day 3 median rtPA-antigen levels were 57.9, 45.9, 64.4 and 40.7 ng/ml in the 0.75, 0.5, 0.375 and 0.25 mg/kg/ d-dosage-groups respectively. The respective values for day 5 were 106.7, 36.4, 38.4 and 61.9 ng/ml. At the end of therapy 58.0, 32.1, 43.5 and 46.2 ng/ml of rtPA-antigen were found in the respective treatment groups. Median rtPA-antigen concentrations were similar in patients with and without bleedings or with and without therapeutic success. No correlation was found between rtPA-antigen Table 1
and PAI-1-activities (day 3, R2:0.019/day 5, R2:0.021) or plasmin-inhibitor-activities on day 3 (R2:0.008); a correlation of borderline significance was found on day 5 (R2:0.32, P:0.045). No correlation was found with any of the activation markers.
Activation markers: TAT, TDP, FgDP, FbDP and d-dimer The concentrations of total-degradation-products (TDP), fibrin-degradation-products (FbDP) and d-dimers were elevated significantly over pre-treatment values at day 3 in all patient groups, for thrombin-antithrombincomplexes (TAT) and fibrinogen-degradation-products (FgDP) only borderline changes were noted (Table 2, Fig. 2). On day 5 no significant changes in relation to pre-treatment results were seen for either parameter in any patient group. TAT, TDP, FbDP and d-dimer results
Fig. 1 (A & B) aPTT- and fibrinogen-values during continuous thrombolytic therapy for DVT in patient groups with different clinical outcomes.
rtPA antigen levels in patient groups with different clinical outcomes
Parameter
rtPA antigen (ng/ml)
345
Day 3
All patients Bleed No bleed Success No success
n1
Median
Range2
18 6 12 7 11
44.3 53.1 41.2 58 41.2
37.4–59.5 45.1–59.5 36.9–60.5 46.7–102.3 36.9–60.5
Day 5
P value3
0.39 0.25
To base4
n1
Median
Range2
P0.0001 P:0.004 P:0.0001 P:0.003 P:0.0001
13 3 10 5 8
39 53.3 36.2 84.7 37.5
33.6–58.2 49.8–144.4 27.6–58.2 36.4–106.7 30.6–51.6
P value3
To base4
0.12
P0.0001 P:0.02 P:0.0002 P:0.006 P:0.0005
0.18
1
number of patients; 225th–75th percentile; 3for comparison between subgroups; 4comparison to baseline test result; rtPA, recombinant tissue-type plasminogen activator.
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Table 2
Activation markers in patient groups with different clinical outcomes
Parameter
Day 3
n1 TAT concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 TDP concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 FgDP concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 FbDP concentration (g/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 d-dimer concentration (ng/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15
Day 5
Median
Range2
P value3
17.3 20.6 16.1 9.3 30.1
9–39 9.3–42.2 8.8–38.9 8.9–18.5 12.4–39.3
0.45
8 22.6 6.3 3.9 12.8
3.9–33 3.8–47.5 3.9–32.6 2.8–22.6 4.9–47.5
1 2.2 0.8 1 1
0.7–4.5 1–4.8 0.5–1.9 0.6–4.2 0.8–6.3
4.5 7.5 4.1 2.5 7.1
2.5–24.7 2.5–35.4 2.4–24.1 1.8–7.5 4.1–35.4
0.43
4.5 5.4 4.3 3 8.4
2.4–16.3 3–30.3 2.3–13 1.8–3.3 3.3–27.3
0.43
0.11
0.35 0.09
0.07 0.61
0.09
0.07
To base4
n1
Median
Range2
P:0.22 P:0.90 P:0.10 P:0.93 P:0.10
19 5 14 7 12
23.5 23.5 22 11.8 25.7
8.7–37.7 10.1–23.9 8.7–37.7 5.6–46.2 11.2–34
P:0.0008 P:0.01 P:0.05 P:0.01 P:0.01
18 4 14 6 12
5.7 18 5.3 4.7 11.6
2–14.7 3.8–35.4 2–13 2–5.6 2.4–19.8
P:0.06 P:0.05 P:0.46 P:0.33 P:0.08
19 5 14 7 12
0.8 8 0.6 0.7 0.8
0.5–1.8 1.3–7.8 0.4–1.4 0.4–1.8 0.5–2.6
P:0.001 P:0.01 P:0.04 P:0.02 P:0.008
18 4 14 6 12
3.5 8.7 3.5 2.1 8.7
1.2–10.8 1.3–20.4 1.2–10.2 1.2–2.8 1.4–13.8
P:0.003 P:0.01 P:0.09 P:0.02 P:0.02
18 4 14 6 12
3.5 9.6 3.5 1.8 9.1
1.5–10 1.5–20 1.5–9.8 1.5–3.2 1.6–11.8
P value3
To base4
0.78
P:0.39 P:0.54 P:0.10 P:0.87 P:0.31
0.67
0.26 0.13
0.04 0.61
0.67 0.13
0.42 0.10
P:0.07 P:0.06 P:0.26 P:0.13 P:0.10 P:0.6 P:0.14 P:0.66 P:0.96 P:0.53 P:0.10 P:0.26 P:0.32 P:0.19 P:0.10 P:0.16 P:0.29 P:0.37 P:0.48 P:0.15
1
number of patients; 225th–75th percentile; 3for comparison between subgroups; 4comparison to baseline test result; TAT, thrombinantithrombin-complex; TDP, total-degradation-products; FgDP, fibrinogen-degradation-products; FbDP, fibrin-degradation-products.
were comparable for patients with and without bleedings. FgDP concentrations were elevated in patients with bleedings with the differences to patients without bleeding reaching borderline significance. All markers of coagulation activation were similar in patients with and without recanalization. A correlation was seen between TDP and TAT (day 3, R2:0.58/day 5, R2:0.26), FgDP (0.83/0.60), FbDP (0.96/0.96) or d-dimer (0.67/0.83). No correlation was found between any of the activation markers and plasmin-inhibitor- or PAI-1-activities.
Plasminogen, plasmin-inhibitor (formerly ␣2-antiplasmin) and PAI-1 Activities of plasmin-inhibitor, plasminogen-activatorinhibitor 1 (PAI-1) and plasminogen were decreased significantly in all patient groups on day 3 compared to baseline values (Table 3, Fig. 3). On day 5 the significant decrease persisted in all patient groups for plasmininhibitor and PAI-1 activity, for plasminogen a persistant, significant decrease was noted only in the overall patient group and for patients with bleedings or therapeutic Fibrinolysis & Proteolysis (2000) 14(6), 343–350
success. Patients with and without recanalization showed comparable plasminogen, plasmin-inhibitor and PAI-1 activities. Plasminogen activities in patients with bleeding were insignificantly lower compared to patients without bleeding. Plasmin-inhibitor and PAI-1 activities were significantly lower in patients with bleedings in comparison to those without. Clinical, safety and patency data Median number of treatment days was 6.19 (range 1.95–14.25). Treatment was terminated early because of bleeding events in 10/26 patients (0.75 mg: 4/5 patients; 0.5 mg: 4/8 patients; 0.375 mg: 2/7 patients; 0.25 mg: 0/6 patients). Detailed analysis of major bleedings in the 0.75 mg-group revealed one retroperitoneal bleeding on day 3, two cases of gross macrohaematuria on days 3 and 4 and one extensive puncture-site bleeding involving the arm on day 2; in the 0.5 mg-group there were two retroperitoneal bleedings on days 4 and 6, one intraabdominal bleeding on day 3 and one incidence of © 2000 Harcourt Publishers Ltd
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A
C
B
D
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Fig. 2 (A–D) Concentrations of fibrinogen-degradation-products (FgDP), fibrin-degradation-products (FbDP), thrombin-antithrombincomplexes (TAT) and d-dimers during continuous thrombolytic therapy for DVT in patient groups with different clinical outcomes. Results are depicted on a logarithmic scale and presented as means with 25th–75th percentile range (bars).
Table 3
Plasmin-inhibitor-, PAI-1- and plasminogen activities in patient groups with different clinical outcomes
Parameter
Day 3
n1 Plasmin-inhibitor activity (%) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 PAI-1 activity (AU/ml) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15 Plasminogen activity (%) All patients 24 Bleed 9 No bleed 15 Success 9 No success 15
Median 75 53 81 79 73 5.5 0 11 7 4 104 97 109 98 105
Range2 55.5–85 51–57 77–89 57–81 53–89
Day 5
P value3
To base4
n1
Median
Range2
0.0002
P0.0001 P:0.0002 P:0.0007 P:0.0003 P:0.0002
19 5 14 7 12
77 35 80.5 79 72.5
64–84 27–65 68–87 60–84 64.5–85.5
P:0.0001 P:0.003 P:0.01 P:0.002 P:0.01
19 5 14 7 12
2 0 5 5 2
P:0.009 P:0.0005 P:0.49 P:0.04 P:0.09
18 4 14 6 12
112.5 101.5 114.5 100 114.5
0.86
0–11.5 0–0 4–15 0–12 0–11
0.01
94.5–120 83–104 96–130 88–109 95–126
0.03
0.93
0.29
0–16 0–0 0–17 0–16 0–12.5 93–119 86–112.5 97–119 89–111 97.5–124.5
P value3
0.02 0.77
0.009 0.87
0.18 0.11
To base4
P0.0001 P:0.002 P:0.0004 P:0.001 P:0.0003 P:0.0003 P:0.004 P:0.01 P:0.007 P:0.01 P:0.03 P:0.02 P:0.31 P:0.03 P:0.23
1
number of patients; 225th–75th percentile; 3for comparison between subgroups; 4comparison to baseline test result; PAI-1, plasminogen activator inhibitor 1.
prolonged macrohaematuria on day 6; in the 0.375 mggroup there were two incidences of severe macrohaematuria on days 6 and 7. No other side-effects attributable to thrombolytic treatment were noted. All patients made © 2000 Harcourt Publishers Ltd
a full recovery and were discharged from hospital receiving long-time oral anticoagulant treatment. Complete or good partial recanalization was achieved in 9/26 patients (0.75 mg: 3/5 patients; 0.5 mg: 3/8 patients; Fibrinolysis & Proteolysis (2000) 14(6), 343–350
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Fig. 3 (A & B) Plasmin-inhibitor- and PAI-1-activities during continuous thrombolytic therapy for DVT in patient groups with different clinical outcomes. Results are depicted on a linear scale and presented as means with 25th–75th percentile range (bars).
0.375 mg: 1/7 patients; 0.25 mg: 2/6 patients), moderate partial recanalization or thrombus reduction was seen in an additional 3/26 patients (all in the 0.375 mg group). Phlebograms allowing detailed evaluation could be obtained in 16/26 patients. Marder score decreased from 25.5 to 22 in the overall study group (0.75 mg: 20–18; 0.5 mg: 26.75–21; 0.375 mg: 23–18.7; 0.25 mg: 28.7–26.1). DISCUSSION Analyses of the coagulation system In numerous studies it has been tried to correlate the bleeding risk with changes of haemostatic variables; in accordance with previous reports, we found no significant difference of fibrinogen levels in patients with vs without bleeding complications. Fibrinogen levels were at all times above the lower limit of the normal range17 (Fig. 1B). The measurement of fibrin(ogen) degradation products (FDP) is of special interest in the context of bleeding for two reasons. FDPs interfere with clot formation and lead to the formation of instable clots highly susceptible to lysis and high FDP concentrations, especially high FgDP concentrations, may be indicative of (uncontrolled) systemic plasmin-activity.18 In theory therefore, high FDP concentrations should be associated with an increased bleeding tendency, and indeed we did find a trend towards higher concentrations of TAT, TDP, Fibrinolysis & Proteolysis (2000) 14(6), 343–350
FbDP, FgDP and d-dimer in patients with bleedings, with the differences reaching borderline significance for FgDP, an observation which has also been made in the setting of thrombolysis for AMI19 (Fig. 2). Control of plasminogen-activator induced and plasmin-mediated fibrinolysis is maintained mainly through PAI-1- and plasmininhibitor-activity. During short-term thrombolysis for AMI a (near) total consumption of these inhibitors with prompt rebound supra-normal elevation is found.20,21 No correlation with bleeding events could be demonstrated in these studies. During continuous thrombolysis for DVT we saw a progressive decline in PAI-1- and plasmininhibitor-activities in the overall group with significantly lower values in patients with bleeding complications as compared to patients without bleedings (Fig. 3). We conclude that control of systemic plasmin activity is a main determinant of bleeding complications during continuous thrombolytic therapy. On the basis of these findings we hypothesize, that serial measurements of PAI-1- and plasmin-inhibitor-activities could increase the safety of long-term thrombolysis. The number of patients investigated in our study, however, was too small to draw reliable conclusions. Our preliminary findings need to be confirmed in larger, prospective trials. Moreover, it remains unclear, whether or not the determination of PAI-1 and plasmin-inhibitor activities represent the most suitable markers for an enhanced bleeding risk under continuous thrombolytic therapy with rtPA. In the early days of therapeutic fibrinolysis it has been claimed, that for the achievement of thrombolysis a ‘lytic state’ with near-total consumption of fibrinogen is necessary.22 Since then it was shown in various studies, that no correlation exists between fibrinogen activity and thrombolytic efficacy.17 These findings are once again confirmed for continuous thrombolysis for DVT. Trials of thrombolytic therapy for AMI tried to establish a correlation between rtPA levels and success rates; however, a clear correlation could never be documented.19 In accordance with these findings, we did not find different rtPA-antigen concentrations in patients with or without therapeutic success in our study. Moreover, we did not find a clear correlation between the rtPA dose administered and rtPA antigen plasma levels. This finding is probably mostly due to individually heterogeneous rtPA metabolism, including different rates of rtPA complex formation, mainly with PAI-1, and clearance. In addition we found no correlation of rtPA antigen with PAI-1 or plasmin-inhibitor activities or any of the activation markers. Thus in our experience there is no marker to predict or monitor an rtPA effect. Enhanced concentrations of markers of thrombin-generation (prothrombin fragments 1;2) and/or thrombin-activity (TAT) indicate a shift of the coagulation balance towards enhanced procoagulant activity and elevated concentrations of © 2000 Harcourt Publishers Ltd
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FDPs (TDP, FbDP, FgDP and d-dimers) are markers of an activated coagulation system.23,24 Coagulation activation and enhanced procoagulant activity are associated with resistance to thrombolytic therapy and rethrombosis.17,25,26 In keeping with this, we found higher TAT, TDP, FbDP and d-dimer concentrations in patients without therapeutic success when compared to patients with reperfusion; however these differences were not statistically significant (Fig. 2). Clinical data The overall bleeding rates observed in our study are comparable to those reported from other studies varying from 13 to 57%, with major bleedings being reported from 2.2 to 27% (overview in Grohmann et al.27). Recanalization rates in our substudy were comparable to recanalization rates from other studies on systemic thrombolysis in DVT, ranging from 28 to 80% (overview in Grohmann et al.27). Whether a substantial improvement of recanalization rates is achievable with locoregional thrombolysis and/or with more effective anticoagulation, e.g. with hirudin, is still a matter of debate and ongoing investigations. It is noteworthy that in our small and, theoretically, well-monitored group of patients, satisfactory prolongation of aPTT under therapy with unfractionated heparin was achieved in only 35% of patients, very probably contributing to the disappointingly low reperfusion rates. A clear trend towards higher bleeding (8/13) and higher success rates (6/13) was evident in the two groups receiving the higher rtPA doses (0.75 and 0.5 mg/kg/d) compared to the two lower dose groups (2/13 and 3/13). Thus the dosage regimen with optimal efficacy and safety remains unknown. We feel, however, that rtPA doses exceeding 0.5 mg/kg/d should not be used for continuous thrombolysis in DVT. CONCLUSION Based upon our findings of significantly lower activities of PAI-1 and plasmin-inhibitor in patients with bleeding complications it is hypothesized that (uncontrolled) systemic plasmin activity confers an increased risk of bleeding complications during continuous thrombolysis with rtPA for DVT. Repeated control of these parameters and adjustment of the treatment according to the results may increase the safety of thrombolysis in this setting. Elevated concentrations of FDPs are indicators of insufficient control of thrombin activation and formation, leading to resistance to thrombolysis and/or rethrombosis; whether more effective anticoagulants, such as hirudin, could improve further the results of thrombolytic therapy in DVT remains speculative and requires further investigation. High patency rates have been reported from © 2000 Harcourt Publishers Ltd
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studies investigating catheter-directed, regional thrombolysis for DVT. In addition, relatively low rates of bleeding complications have been observed.28,29 These encouraging results warrant extended investigation, as thrombolytic treatment of venous thromboembolism is still underused.4 A combined approach of ‘high-performance thrombolysis’, together with a closely monitored haemostatic system to prevent bleeding complications, may facilitate a more extensive use of thrombolysis for venous thromboembolism and hereby prevent substantial long-term morbidity.
ACKNOWLEDGEMENTS The authors are indebted to the teams of the coagulation laboratory and the intensive care unit at the University Hospital of Ulm for their excellent cooperation. The assistance of Dr A. Riedel, Boehringer Ingelheim Pharma KG, in the preparation of the manuscript is appreciated. The multi-centre trial was supported by the former Dr Karl Thomae GmbH, now Boehringer Ingelheim Pharma KG, Biberach, Germany. REFERENCES 1. Goldhaber SZ. Thrombolytic therapy. Adv Int Med 1999; 44: 311–325. 2. Grünewald M, Seifried E. Meta-analysis of all available published clinical trials (1958–1990) on thrombolytic therapy for AMI: relative efficacy of different therapeutic strategies. Fibrinolysis 1994; 8: 67–86. 3. Ludlam CA, Bennett B, Fox KAA, Lowe GDO, Reid AW. Guidelines for the use of thrombolytic therapy. Blood Coag Fibrinol 1995; 6: 273–285. 4. Sasahara A. Venous thromboembolic disease: who should receive thrombolytic treatment? Plenary lecture at the XVIIth Congress of the International Society on Thrombosis and Haemostasis, Washington, July 1999. 5. Indications for fibrinolytic therapy in suspected acute myocardial infarction: collaborative overview of early mortality and major morbidity results from all randomised trials of more than 1000 patients. Fibrinolytic Therapy Trialists’ (FTT) Collaborative Group. Lancet 1994; 343: 311–322. 6. Prandoni P, Lensing AW, Cogo A et al. The long-term clinical course of acute deep venous thrombosis. Ann Intern Med 1996; 125: 1–7. 7. Carter CJ. The natural history and epidemiology of venous thrombosis. Prog Cardiovasc Dis 1994; 36: 423–438. 8. Ng CM, Rivera JO. Meta-analysis of streptokinase and heparin in deep vein thrombosis. Am J Health Syst Pharm 1998; 55: 1995–2001. 9. Weinmann EE, Salzman EW. Deep-vein thrombosis. N Engl J Med 1994; 331: 1630–1641. 10. Comerota AJ, Aldridge SC. Thrombolytic therapy for deep venous thrombosis: a clinical review. Can J Surg 1993; 36: 359–364. 11. Rogers LQ , Lutcher CL. Streptokinase therapy for deep vein thrombosis: a comprehensive review of the English literature. Am J Med 1990; 88: 389–395.
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