Recent data have suggested that standard unfractionated heparin (UFH) protocols may over-anticoagulate obese patients. The goal of this retrospective study was to observe differences in anticoagulation parameters and safety outcomes for standardized antifactor Xa UFH protocols in obese and non-obese populations. Obese patients (N = 148) were identified over a 20-month period and matched to 148 non-obese patients based on age, gender, and admission date. Patients were included if they were on one of three approved UFH protocols [high (target antifactor Xa 0.3-0.7 IU/mL), moderate (0.3-0.5 IU/mL), or low (0.1-0.2 IU/mL) dose] for ≥24 consecutive hours and had ≥1 antifactor Xa level drawn during the infusion. Groups were compared for doses at first and second consecutive therapeutic antifactor Xa level, major bleeding, and in-hospital mortality. Obese patients required a significantly lower mean weight-based infusion rate to attain first therapeutic antifactor Xa level compared to non-obese patients in both the high dose (19.45 vs. 15.29 units/kg/h, p < 0.001) and the moderate dose populations (15.0 vs. 12.94 units/kg/h, p = 0.003). Similarly, patients in both the high and moderate dose populations had significant differences in mean infusion rates to attain second consecutive therapeutic antifactor Xa levels. There was no difference between infusion rates for the primary outcomes in the low dose population. There was no difference between groups in major bleeding or mortality outcomes. Similar to data using UFH protocols based on activated partial thromboplastin time, obese patients require lower weight-based UFH doses to attain therapeutic anticoagulation. Institutions using or changing to antifactor Xa based protocols may need to modify protocols for obese patients.

Background: Enoxaparin is commonly used for venous thromboembolism (VTE) prophylaxis in hospitalized patients. Published literature exists for dose adjustment in higher body weights and renal dysfunction, but sparse literature on optimal dosing of prophylactic enoxaparin in underweight patients exists. Objective: To determine if there is a difference in adverse outcomes or effectiveness if enoxaparin VTE prophylaxis dosing is reduced to 30 mg subcutaneously once daily from standard dosing in underweight medically ill patients. Methods: This study was a retrospective chart review of a total of 171 patients, with 190 individual courses of enoxaparin included. Patients were ≥18 years of age, weighed ≤50 kg, and were given at least 2 days of consecutive therapy. Patients were excluded if they were taking anticoagulation upon admission, had a creatinine clearance <30 mL/min, were admitted to the ICU or a trauma or surgical service, or presented with bleeding or thrombosis. The Padua score and a modified score from the IMPROVE trial were used to evaluate baseline thrombotic risk and bleeding risk, respectively. Bleeding events were classified using the Bleeding Academic Research Consortium criteria. Results: No difference was seen in baseline risk of bleeding or thrombosis when comparing the reduced and standard dosing groups. No differences were observed with rates of bleeding, thrombotic events, mortality, or 30-day readmission. Conclusion: Both reduced and standard dosing strategies appeared effective for VTE prophylaxis, but neither showed superiority in reducing bleeding events. Additional larger studies are needed to evaluate safety and effectiveness of reduced dose of enoxaparin in this patient population.

A rare, yet serious, complication of mechanical heart valves is symptomatic obstructive prosthetic valve thrombosis. The risk of valve thrombosis is magnified in patients who are nonadherent to prescribed anticoagulation. In this case report, we describe a 48-year-old male patient with a history of mechanical aortic valve replacement surgery, who stopped taking prescribed warfarin therapy 2 years before presentation and subsequently developed acute decompensated heart failure secondary to valvular dysfunction. Low-dose alteplase therapy was administered successfully with no bleeding complications and a complete return of valvular function.

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