Basal high-sensitivity-C-reactive protein levels in patients with spontaneous venous thromboembolism.

The role of C-reactive protein (CRP) in venous thromboembolism (VTE) is still under discussion because of controversial results in the literature. Conflicting data may have partly been due to bias by exogenous factors altering CRP levels. We investigated CRP concentrations in patients with spontaneous VTE applying a study design that allowed the measurement of basal high sensitivity (hs)-CRP levels. Patients with a history of deep vein thrombosis (DVT, n=117) and pulmonary embolism (PE, n=97) were compared to healthy individuals (n=104). Hs-CRP levels (mg/dl) were significantly higher in patients (n=214, median/interquartile range: 0.171/0.082-0.366) than in controls (0.099/0.053-0.245, p=0.001). The unadjusted odds ratio (OR) for VTE per 1 mg/dl increase of CRP was 2.8 [95% confidence interval (CI): 1.1-6.8, p=0.03]. This association remained significant after adjustment for factor V Leiden, prothrombin G20210A and factor VIII activity above 230% (OR = 2.9, 95% CI [1.1-7.5]), but became remarkably attenuated and lost its statistical significance after adjustment for BMI alone (OR = 1.7 [0.7-4.0]). CRP was also not independently associated with VTE in subgroups of patients (those with DVT without symptomatic PE, those with PE and patients without established risk factor) in multiple regression analysis. In summary, we observed significantly higher basal hs-CRP levels in patients with spontaneous VTE compared to healthy controls. This association was independent of hereditary and laboratory risk factors for VTE, but lost its significance after adjustment for BMI. Increased basal CRP levels do not appear to represent an independent risk factor for VTE.

Medical conditions increasing the risk of chronic thromboembolic pulmonary hypertension.

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by organized thromboemboli that obstruct the pulmonary vascular bed. Although CTEPH is a serious complication of acute symptomatic pulmonary embolism in 4% of cases, signs, symptoms and classical risk factors for venous thromboembolism are lacking. The aim of the present study was to identify medical conditions conferring an increased risk of CTEPH. We performed a case-control-study comparing 109 consecutive CTEPH patients to 187 patients with acute pulmonary embolism that was confirmed by a high probability lung scan. Splenectomy (odds ratio=13, 95% CI 2.7-127), ventriculo-atrial (VA-) shunt for the treatment of hydrocephalus (odds ratio=13, 95% CI 2.5-129) and chronic inflammatory disorders, such as osteomyelitis and inflammatory bowel disease (IBD, odds ratio=67, 95% CI 7.9-8832) were associated with an increased risk of CTEPH.

Haptoglobin phenotype 2-2 as a potentially new risk factor for spontaneous venous thromboembolism.

BACKGROUND AND OBJECTIVES: Haptoglobin (Hp) is a plasma protein that binds free hemoglobin and thus prevents catalysis of reactive oxygen species by the Fenton reaction. A genetic polymorphism has been described that leads to the generation of two distinct alleles, Hp1 and Hp2, which define three major haptoglobin phenotypes, denoted Hp1-1, Hp2-1 and Hp2-2. Hp2-2 has been reported to be associated with the risk of atherosclerosis and coronary heart disease. In our study we investigated the association of haptoglobin genotype and phenotype with the risk of spontaneous venous thromboembolism (VTE). DESIGN AND METHODS: One hundred and twenty-eight patients with a history of spontaneous deep vein thrombosis (70 women, 58 men), 105 with spontaneous symptomatic pulmonary embolism (58 women, 47 men) and 122 healthy controls (60 women, 62 men) were enrolled. Haptoglobin levels were measured immunonephelometrically and phenotypes were detected by polyacrylamide gel electrophoresis and subsequent immunoblotting. RESULTS: The Hp2-2 phenotype was significantly more prevalent in patients (42%) than in controls (30%) and significantly increased the risk for VTE in univariable (odds ratio=1.6, 95% confidence interval [1.0-2.6], p=0.04) and multivariable analyses (odds ratio=1.9 [1.0-3.4], p=0.04). Hp2-2 (n=134) was associated with significantly lower haptoglobin levels (median=89.7 mg/dL) than Hp2-1 (n=170, median = 123.5 mg/dL, p<0.001) or Hp1-1 (n=51, median=142.8 mg/dL, p<0.001). INTERPRETATION AND CONCLUSIONS: Our study gives the first evidence that Hp2-2 represents a risk factor for spontaneous VTE, presumably through a pathophysiological mechanism similar to that in arterial disease.

Symptomatic pulmonary embolism and the risk of recurrent venous thromboembolism.

BACKGROUND: In patients with a first symptomatic pulmonary embolism (PE), the risk of recurrence is unknown. We therefore investigated the risk of recurrence among patients with spontaneous symptomatic PE and among those with deep vein thrombosis (DVT) without symptoms of PE. METHODS: After discontinuation of secondary thromboprophylaxis for a first venous thromboembolism (VTE), we prospectively observed 436 patients for an average of 30 months. Patients with secondary VTE, natural inhibitor deficiencies, lupus anticoagulant, cancer, long-term antithrombotic therapy, vena cava filters, or pregnancy were excluded. The study outcome was objectively documented recurrent symptomatic VTE. RESULTS: Recurrent VTE was seen among 28 (17.3%) of 162 patients with symptomatic PE and among 26 (9.5%) of 274 patients with DVT without symptoms of PE. Compared with patients with DVT, the relative risk of recurrent VTE among patients with symptomatic PE was 2.2 (95% confidence interval, 1.3-3.7; P =.005). The relative risk was not affected by age, sex, presence of factor V Leiden or prothrombin G20210A, hyperhomocysteinemia, or high factor VIII levels. Compared with patients with DVT without symptoms of PE, patients with symptomatic PE had an adjusted relative risk of PE at recurrence of 4.0 (95% confidence interval, 1.3-12.3; P =.03). CONCLUSION: Patients with a first symptomatic PE not only have a higher risk of recurrent VTE than those with DVT without symptoms of PE, but are also at high risk of symptomatic PE at recurrence.

The risk of recurrent venous thromboembolism in heterozygous carriers of factor V Leiden and a first spontaneous venous thromboembolism.

BACKGROUND: Factor V (FV) Leiden is a risk factor for venous thrombosis (VT). Data on its influence on the risk of recurrent venous thromboembolism (VTE) are controversial owing to different study designs and patient cohorts. METHODS: We reevaluated the risk of recurrence among heterozygous carriers and noncarriers of FV Leiden with a first spontaneous proximal VT of the leg and/or pulmonary embolism. Patients with secondary VTE, homozygous FV Leiden, natural inhibitor deficiencies, lupus anticoagulant, cancer, or long-term anticoagulation were excluded. The study end point was objectively documented, symptomatic, recurrent VTE. RESULTS: After discontinuation of oral anticoagulant therapy for a first VTE, we prospectively observed 287 patients, 83 (29%) of whom were heterozygous for FV Leiden. Recurrent VTE was seen in 17 (20%) of 83 patients with and 44 (21.6%) of 204 without FV Leiden. The probability of recurrence among heterozygotes was 12% (95% confidence interval [CI], 8%-16%), 27% (95% CI, 21%-33%), and 27% (95% CI, 21%-33%) after 2, 4, and 6 years, respectively, and was not higher than that among patients without the mutation (16%, 23%, and 34%, respectively). The relative risk of recurrence in heterozygotes was 0.9 (95% CI, 0.5-1.6; P =.60) after adjustment for confounding variables. The risk of recurrence among patients with and without FV Leiden was not different when sex distribution or duration of anticoagulation therapy was taken into account. CONCLUSIONS: The risk of recurrence is similar among carriers and noncarriers of FV Leiden. Heterozygous patients should receive secondary thromboprophylaxis for a similar length of time as patients without FV Leiden.

The effect of beta-receptor blockade on factor VIII levels and thrombin generation in patients with venous thromboembolism.

High factor VIII (FVIII) is a risk factor for venous thromboembolism (VTE). The pathomechanism by which high FVIII leads to an increased risk of VTE is unknown. Physical activity and infusion of adrenalin provoke a rise in FVIII, which can be blocked by a nonselective beta-blockade. We tested the hypothesis that in patients with a VTE beta-blockade decreases FVIII and inhibits coagulation activation. 17 male patients with high FVIII (> 170 IU/dL, n = 7) or low FVIII (<150 IU/dL, n = 10) and a history of VTE received 40 mg of propranolol thrice daily for 14 days. FVIII and vasopressin levels were measured before and during propranolol intake and 28 days thereafter. At the same time points, haemostatic system activation was investigated by measuring prothrombin fragment f1.2 (f1.2) and thrombin antithrombin complexes (TAT) in venous blood and in blood emerging from a skin incision (shed blood). The mean FVIII level before propranolol was 192 IU/dL and 115 IU/dL in patients with high and low FVIII, respectively. During and 28 days after propranolol, no significant change in FVIII was seen in both groups. Changes in f1.2 and TAT were not detectable in either venous blood or in shed blood. beta-receptor blockade did not lower FVIII or inhibit haemostatic system activation in patients with VTE and persistently high FVIII. Administration of propranolol cannot be recommended as secondary thromboprophylaxis in patients with high FVIII.

Prospective evaluation of coagulation activation in pregnant women receiving low-molecular weight heparin.

Pregnancy is a major risk factor for venous thromboembolism (VTE), and low-molecular weight heparin (LMWH) seems to be safe and effective in pregnant women. Normal pregnancy is accompanied by a state of hypercoagulability, indicated by an increase in markers of coagulation activation. In a prospective cohort study, we followed 61 women who received LMWH thromboprophylaxis throughout pregnancy because of a history of VTE, hereditary thrombophilia and/or previous pregnancy-related complications. The control group consisted of 113 healthy pregnant women without antithrombotics. D-Dimer, prothrombin fragment F1+2 (F1+2) and the resistance to activated protein C (APC-ratio) were measured in all women during the first, second and third trimester. Patients and controls did not significantly differ with regard to baseline characteristics and pregnancy outcome. A (recurrent) VTE was seen in one patient despite LMWH. D-Dimer levels significantly increased among patients and controls during pregnancy (p < 0.0001), and were significantly higher among patients compared with the controls (p <0.0001) [395 ng/ml (95% CI 340-458) and 249 ng/ml (95%CI 234-266); 710 ng/ml (95% CI 602-838) and 475 ng/ml (95% CI 431-523); 1089 ng/ml (95% CI 931-1273) and 822 ng/ml (95% CI 741-911); respectively]. Levels of F1+2 significantly increased while the APC-ratio significantly decreased during pregnancy among patients and controls. Despite LMWH, pregnancy is accompanied by a substantial activation of the coagulation system.

Thrombin-activatable fibrinolysis inhibitor and the risk for recurrent venous thromboembolism.

The impact of fibrinolysis for predicting the risk for recurrent venous thromboembolism (VTE) is low. We prospectively followed up 600 patients with a first VTE and evaluated the thrombin-activatable fibrinolysis inhibitor (TAFI) as a risk factor for recurrence. A high TAFI level (75th or higher percentile in thrombosis patients) was associated with a 2-fold higher risk for recurrence compared with lower levels. The probability of recurrence 2 years after anticoagulation was 14.5% (95% confidence interval [CI], 8.6-20.4) among patients with high TAFI levels and 6.8% (95% CI, 4.3-9.3) among patients with lower levels (P =.006). Our data also support the concept of a linkage between fibrinolysis and the coagulation system. Patients with high TAFI levels had significantly higher levels of factors XI, VIII, and IX, and a high risk of recurrence was seen among patients with high TAFI levels and high levels of one of these factors. The relative risk (RR) for recurrence was highest among patients with high TAFI and high factor XI (RR, 2.9; 95% CI, 1.3-6.9), high factor VIII (RR, 6.5; 95% CI, 2.9-14.8), or high factor IX (RR, 2.0; 95% CI, 1.0-3.9) levels compared with patients with low levels of TAFI and one of these factors.

Superficial thrombophlebitis and risk for recurrent venous thromboembolism.

OBJECTIVE: Superficial thrombophlebitis (ST) is a frequent and potentially serious disease if complicated with venous thromboembolism (VTE). Data on risk factors and incidence rates for ST are scarce. It is also unknown whether ST is a risk factor for recurrence of VTE. METHODS: After discontinuation of secondary thromboprophylaxis for a first spontaneous VTE, we prospectively observed 615 patients on average for 30 +/- 26 months. Patients with natural coagulation inhibitor deficiency, lupus anticoagulant, or cancer, who were pregnant, or were receiving long-term antithrombotic therapy were excluded. The study outcomes were occurrence of symptomatic ST or objectively documented recurrent symptomatic VTE. RESULTS: ST developed in 45 patients (7.3%) with a first VTE. High factor VIII concentration emerged as an independent risk factor for ST (relative risk [RR], 2.0; 95% confidence interval [CI], 1.0-5.2), compared with lower levels after adjustment for age and sex; factor V Leiden and prothrombin G20210A concentration; hyperhomocysteinemia; high body mass index; and duration of oral anticoagulation therapy. VTE recurred in 12 (27%) of 45 patients with ST and in 67 (12%) of 570 patients without ST. In patients with VTE, subsequent ST emerged as an independent risk factor for recurrent VTE. Patients with ST had twofold higher RR (2.1; 95% CI, 1.0-4.2) for recurrence than did patients without ST after adjustment for putative confounding variables. CONCLUSION: Patients with a first spontaneous VTE and subsequent ST are at increased risk for recurrent VTE. High factor VIII concentration is an independent risk factor for ST.