Clinical Outcomes with Unfractionated Heparin or Low-Molecular-Weight Heparin as Bridging Therapy in Patients on Long-Term Oral Anticoagulants: Results from the REGIMEN Registry.

Abstract Introduction: The optimal perioperative management of patients on long-term oral anticoagulant (OAC) therapy is currently unclear. There have been no large prospective clinical studies comparing unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) as bridge therapy in this setting. This registry compared the efficacy and safety of in-hospital UFH with mostly outpatient-based LMWH for perioperative bridging in patients on long-term OAC. Methods: REGIMEN is a large, prospective, multi-center registry in the USA and Canada of patients receiving chronic anticoagulation and requiring a perioperative bridge for an elective procedure or surgery. Patients who were ≥18 years, on OAC ≥3 months prior to the elective procedure, and who had heparin as a bridge to OAC for ≥2 days in the pre- and/or post-operative period, were included in the registry. Data on patient characteristics and primary clinical adverse events up to 30 days post-procedure were collected and compared between UFH and LMWH. Results: Of 1077 patients enrolled in this registry, 180 received UFH alone and 721 received LMWH (treatment or prophylactic dose) alone. Patients not receiving the same heparin pre- and post-procedure (n=123) and those undergoing multiple procedures (n=53) were excluded from the analysis. Patients on LMWH spent less time in hospital and were less likely to undergo major surgery or receive general anesthesia. Adverse events occurred at similar rates in both groups (table 1), and were primarily minor bleeds. Univariate analysis for procedure variables showed that UFH versus LMWH, intra-procedural anticoagulants/thrombolytics, procedure duration ≥45 minutes and general anesthesia were associated with an increased risk of a major adverse event. Logistic regression analysis for major bleeding can be seen in table 2. Conclusions: REGIMEN, a large, prospective, multi-center registry of patients in the US and Canada requiring bridging therapy with heparin for elective surgery, reveals that bridging therapy with LMWH in selected outpatients is at least as safe and effective as in-hospital UFH. Table 1. Adverse events in bridged patients UFH (n=164) LMWH (n=668) p-value Adverse event 28 (17.1%) 108 (16.2%) 0.81 Arterial/venous complication, major bleed, or death 13 (7.9%) 28 (4.2%) 0.07 Adverse Events: Arterial complications: Cardiac valvular or mural thrombus 1 (0.6%) 0 (0%) Intracranial event 1 (0.6%) 2 (0.3%) TIA 1 (0.6%) 2 (0.3%) Peripheral arterial event 1 (0.6%) 0 (0%) Venous complications: DVT 0 (0%) 2 (0.3%) PE 0 (0%) 0 (0%) Major bleed 9 (5.5%) 22 (3.3%) 0.25 Minor bleed 15 (9.1%) 80 (12.0%) 0.34 Thrombocytopenia 2 (1.2%) 3 (0.4%) Death 2 (1.2%) 4 (0.6%) Table 2. Logistic regression analysis for major bleed Independent variable Reference OR 95% CI Vascular surgery Not vascular surgery 4.72 0.92–24.09 General surgery Not general surgery 2.25 0.78–6.53 Charlson score >1 Charlson score ≤1 2.24 1.02–4.93 Procedure duration ≥45mins Procedure duration <45mins 1.37 0.59–3.18 LMWH post-op UFH post-op 0.76 0.32–1.81

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