Differential Effects of Clopidogrel With or Without Aspirin on Platelet Reactivity and Coagulation Activation: A Randomized Trial in Healthy Volunteers.

Dual antiplatelet therapy (DAPT) is standard in acute coronary syndrome but confers a bleeding risk. To compare effects of clopidogrel single antiplatelet therapy (SAPT) with clopidogrel-based DAPT on hemostatic system activation we conducted a randomized clinical trial in 44 volunteers (clopidogrel (d1: 600 mg, d2-6: 150 mg) ± aspirin (100 mg)). Multiple electrode aggregometry-adenosine diphosphate (MEA-ADP) and MEA-arachidonic acid (MEA-AA) triggered aggregometry, vasodilator-stimulated phosphoprotein (VASP), beta thromboglobulin, p-selectin, thromboxane B2 , d-Dimer, prothrombin fragment 1.2 (f1.2), and a phospholipid-dependent clotting time were measured in venous blood. Changes are described by mean differences (Δmean (95% confidence interval (CI)) or geometric mean ratios (95% CI)). DAPT and SAPT comparably and significantly decreased MEA-ADP at 2 hours (-60% vs. -63%; P = 0.35, Δmean -4.9, 95% CI -15.4 to 5.5). At 24 hours (-59% vs. -47%, P = 0.04, Δmean -11.1, 95% CI -21.7 to -0.4]) and 8 days (-61% vs. -53%, P = 0.04, Δmean -11.3, 95% CI -22.0 to -0.6). Both treatments significantly reduced VASP and MEA-AA after 2 hours and 8 days. DAPT inhibited MEA-AA significantly stronger at 2 hours (-77% vs. -30%; P < 0.0001, Δmean -39.6, 95% CI -54.2 to -25.0), at 24 hours (-80% vs. -27%, P < 0.0001, Δmean -47.8, 95% CI -62.3 to -33.3), and 8 days (-79% vs. -27%, P < 0.0001, Δmean -48.9, 95% CI -62.5 to -35.4). Neither treatment significantly influenced beta thromboglobulin or p-selectin. DAPT abolished and SAPT reduced thromboxane B2 after 24 hours and 8 days. The d-Dimer was reduced by DAPT (0.94, 95% CI 0.89-1.00, P = 0.04) at 2 hours but not after 24 hours and 8 days. SAPT did not decrease d-Dimer. Neither treatment affected f1.2. DAPT and SAPT comparably affect platelet and coagulation activation in venous blood.

Dabigatran: patient management in specific clinical settings.

Dabigatran, a direct thrombin inhibitor, is licensed for the prevention of venous thromboembolism after knee and hip replacement, the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation and for the treatment of acute venous thromboembolism. As dabigatran has a favourable benefit-risk profile, it is being increasingly used. Dabigatran differs from vitamin K antagonists as regards its pharmacological characteristics and its impact on certain laboratory tests, and also in the lack of a direct antagonist that can reverse dabigatran-induced anticoagulation. In emergency settings such as acute bleeding, emergency surgery, acute coronary syndrome, thrombolysis for ischaemic stroke or overdosing, specific strategies are required. A working group of experts from various disciplines has developed strategies for the management of dabigatran-treated patients in emergency settings.

Prophylactic efficacy and pharmacokinetically guided dosing of a von Willebrand factor/factor VIII concentrate in adults and children with von Willebrand's disease undergoing elective surgery: a pooled and comparative analysis of data from USA and European Union clinical trials.

BACKGROUND: Surgical intervention may pose significant risk of life-threatening bleeding in patients with von Willebrand's disease; prophylactic treatment with von Willebrand factor/factor VIII concentrate is generally indicated for von Willebrand's disease characterized by moderate to severe qualitative and quantitative deficiencies of Willebrand factor to raise and maintain both Willebrand factor and FVIII at haemostatic levels for surgical prophylaxis. MATERIALS AND METHODS: Since prospective clinical data in such situations were lacking, two recent, prospective, multicentre studies evaluated the prophylactic perioperative use of the on Willebrand factor/ factor VIII concentrates, Humate-P® and Haemate P. Despite some differences in the two studies, one conducted in the USA (n =35) and one in the European Union (n =27), the designs were similar enough to allow for a limited pooled analysis of data. In both studies, preoperative loading doses and subsequent maintenance doses were calculated using individual subject-derived incremental in vivo recovery values, although von Willebrand factor:ristocetin cofactor and FVIII:coagulation activity target levels differed between the protocols. Efficacy was rated daily by the investigator as excellent, good, moderate, or poor. RESULTS: Overall haemostatic efficacy (rating of excellent/good), assessed 24 hours after the last infusion (USA) or taken as the worst rating between surgery and day 14 (EU), was achieved in 95% of the pooled population of 62 adults and children. Efficacy did not appear to be affected by dosing variations. The rate of possibly related adverse events was low (8 subjects; 13%); one of these events was considered serious (pulmonary embolism). DISCUSSION: This pooled analysis of a relatively large number of patients for a rare disease confirms the feasibility of pharmacokinetically guided dosing of von Willebrand factor/factor VIII concentrate and highlights its efficacy and safety in the prevention of excessive perioperative bleeding.

Long-term survival of patients with a history of venous thromboembolism.

Limited data are available regarding long-term survival following venous thromboembolism (VTE). The objectives of this study are to evaluate long-term survival by retrospective survival analysis in patients with a history of VTE and to compare their survival with that of the general population. Patients with a history of VTE (min. 3 months after VTE) without cancer, who were referred to our department between 1994 and 2007, were included in the analysis. Information concerning mortality was available through the Austrian Central Death Register. The survival of patients was compared with that of the age- and gender-matched general Austrian population. Three thousand two hundred-nine patients (mean age, 46.2; range, 14-89 years) were included. Median time interval between the first VTE and inclusion was 14 months; median observation period was 6.6 years. During the considered time period, 169 patients (5.3%) died. The cumulative survival in patients was 0.97 and 0.87 after 5 and 10 years; men had a higher death rate than women; patients with idiopathic VTE had a less favourable survival than those with a triggering event. When patients were compared to the general population, the cumulative relative survival was 1.02 (95% CI 1.00-1.03). In none of the analysed subgroups (different sites of VTE; idiopathic vs. secondary VTE) was a reduced cumulative relative survival found. The relative survival of male patients was even slightly better, whereas that of women equalled that of the normal population. Our results indicate that after the initial phase, VTE does not seem to impair long-term survival of patients with a history of VTE without cancer.

Family history for venous thromboembolism and the risk for recurrence.

PURPOSE: The relevance of a family history for venous thromboembolism with regard to the likelihood for recurrence is unknown. SUBJECTS AND METHODS: We studied 826 patients for an average of 36 months after a first unprovoked venous thromboembolism and withdrawal of oral anticoagulation. Patients with cancer, lupus anticoagulant, or deficiency of antithrombin, protein C, or protein S were excluded. The study endpoint was objective evidence of recurrent symptomatic venous thromboembolism. RESULTS: Recurrence for venous thromboembolism was recorded in 23 of 190 patients (12.1%) with a family history (at least one affected first-degree family member) and in 79 of 636 patients (12.4%) without familial thrombosis (relative risk for recurrence 1.0; 95% confidence interval, 0.7-1.6; P=.9). At 5 years, the likelihood for recurrence was 20% among patients with a family history for venous thromboembolism and 18% among those without a family history for venous thromboembolism (P=.9). Risk determinants for venous thromboembolism including factor V Leiden, factor II G20210A, and high factor VIII were not statistically different between the 2 groups. CONCLUSION: A family history for venous thromboembolism does not segregate patients into high- or low-risk categories and is not suitable to identify patients at increased risk for recurrent venous thromboembolism.

The optimal duration of secondary thromboprophylaxis in patients with venous thromboembolism. The importance of thrombophilia screening.

Venous thromboembolism is a chronic disease with an annual incidence of recurrence of 5 to 10%. Patients with venous thrombosis should be treated with anticoagulants for at least 3 months. The optimal duration of anticoagulation entails balancing the risk of recurrence against the risk of treatment-associated bleeding. Candidates for extended anticoagulation are patients with a high risk of recurrence. The risk of recurrence is increased in patients with antithrombin deficiency, the lupus anticoagulant, homozygous F V Leiden, combined defects, high F VIII, high F IX, high TAFI, hyperhomocysteinemia or more than one episode of thrombosis. The risk of recurrence is low in patients with venous thrombosis secondary to surgery or trauma. Routine thrombophilia screening is aimed at identifying patients who could benefit from extended anticoagulation. This population consists of patients with venous thrombosis at a young age, an unprovoked episode of venous thrombosis, patients with a strong positive family history or patients with recurrent venous thrombosis. Screening should comprise antithrombin determination and the search for the lupus anticoagulant. Patients harbouring one of these defects are at high risk of recurrence and most likely will profit from prolonged anticoagulation. The clinical relevance of new treatment strategies such as extended low-intensity warfarin or administration of the direct thrombin inhibitor (xi-)melagatran is at present unclear.

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.