https://www.armv-paca.org/index.php/mediatheque-full/recommandations-1/mtev-1/accp-2008-1/145-the-perioperative-management-antithrombotic-pdf-1/file

The perioperative management of antithrombotic therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).

Bridging Anticoagulation: Primum Non Nocere.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1538-7836.2009.03649.x

Patients requiring interruption of long-term oral anticoagulant therapy: the use of fixed sub-therapeutic doses of low-molecular-weight heparin.

Vitamin K antagonists (VKA) treatment starts with co-administration of low-molecular-weight heparin (LMWH). The anticoagulation induced by the two drugs is still not well determined. In the present study we used thrombin generation assay to evaluate the hypo-coagulation induced by treatment with VKA and by the combination of VKA with LMWH. Tissue factor triggered thrombin generation in platelet-poor plasma was assessed in samples from 15 healthy volunteers, 97 samples from patients treated with VKA and 41 samples from patients receiving enoxaparin and VKA. Patients were classified according to international normalised ratio (INR) level. In plasma samples from patients treated with VKA having INR 2–3 the inhibition of thrombin generation reached 50% compared to controls. In samples with INR>3 this inhibition was 80%. In samples from patients receiving both LMWH and VKA, thrombin generation was significantly decreased compared to the controls and VKA group. In samples with an INR 2–3 obtained from patients treated with LMWH and VKA, the inhibition of thrombin generation was similar to that observed in samples with an INR>3 obtained from VKA treated patients. Thrombin generation assay is sensitive to detect the global the anticoagulant effect produced by the association of LMWH and VKA. For equal INR dual anticoagulant treatment induces significantly more profound inhibition of thrombin generation compared to treatment with VKA alone. The clinical relevance of this observation merits to be studied in prospective studies in patients with defined indications of anticoagulant therapy.

Differential inhibition of thrombin generation by vitamin K antagonists alone and associated with low-molecular-weight heparin

a B s t r a C t Background: Perioperative bridging with low-molecularweight heparins (LMWH) is applied to minimise the risk of thromboembolism (TE). Guidelines characterise patients at risk and strategies to be followed. We assessed guideline adherence in bridging episodes and identified possible risk factors for bleeding in a retrospective cohort study. Methods: We searched the electronic patient data system of the Maastricht anticoagulation service, the Netherlands. We identified 181 patients on chronic anticoagulation who underwent surgery (222 procedures) and were bridged with LMWH. Guideline adherence was defined in terms of the relation between TE risk and the dose of LMWH administered, the bleeding risk of the procedure and the duration of postprocedural administration of LMWH. Logistic regression was used to identify risk factors for bleeding. Results: Of all low TE risk patients (n=102), 84.3% were treated with therapeutic doses of LMWH. The median duration of postprocedural LMWH administration was eight days. The 30-day incidence of major bleeding in the entire group (n=222) was 11.3%. Two patients (0.90%) experienced a deep venous thrombosis. Creatinine clearance ≤40 ml/min (odds ratio (OR) 5.03, 95% confidence interval (CI) 1.25 to 20.26) and dental procedures (OR 3.32, 95% CI 1.22 to 9.04) were independent predictors for total bleeding. Conclusion: Guideline adherence was low, leading to prolonged bridging procedures, excess treatment of patients and high bleeding rates. The majority of patients had a low thromboembolic risk profile or underwent low-risk procedures. For patients with decreased creatinine clearance, reduced doses of LMWH should be considered to reduce bleeding risk. K e YWords

Practice of bridging anticoagulation: guideline adherence and risk factors for bleeding

Background
Clinical trials involving frequent, standardized monitoring of the international normalized ratio (INR) demonstrated that a short course of low-molecular-weight-heparin (LMWH) can successfully bridge patients to oral anticoagulation. However, rigidly performed INR testing is often not feasible in the outpatient setting in actual clinical practice. The purpose of this study was to determine if the anticoagulation results of clinical trials of LMWH bridging therapy are also achieved in a single-center clinical practice setting.

Jacob P. Deerhake

Papers

The duration of anticoagulation bridging therapy in clinical practice may significantly exceed that observed in clinical trials