Inadequate Anti-Factor Xa Levels With Daily 40-mg Enoxaparin After Cardiac Surgery

Area of Science:

• Cardiology
• Pharmacology
• Vascular Surgery

Background:

• Patients undergoing cardiac surgery face a heightened risk of venous thromboembolism (VTE).
• Effective VTE prophylaxis is crucial for reducing morbidity and mortality in these high-risk patients.
• Optimal VTE prophylaxis strategies in cardiac surgery patients remain under-researched.

Purpose of the Study:

• To evaluate if a standard 40 mg daily subcutaneous dose of enoxaparin achieves therapeutic anti-factor Xa (aFXa) levels for VTE prophylaxis in post-open heart surgery patients.
• To assess the adequacy of standard enoxaparin dosing for VTE prevention in this specific patient cohort.

Main Methods:

• A prospective study included adult patients who underwent open heart surgery with cardiopulmonary bypass and received at least three doses of subcutaneous enoxaparin.
• Patients receiving therapeutic anticoagulation, cardiac transplantation, ventricular assist device, or with renal insufficiency were excluded.
• Steady-state trough serum aFXa levels were measured before the fourth enoxaparin dose.

Main Results:

• The study analyzed data from 44 patients.
• The target aFXa level for adequate prophylaxis was 0.10–0.20 IU/mL.
• The mean aFXa level achieved was 0.049 IU/mL, significantly lower than the target range (P < .001).

Conclusions:

• Standard daily subcutaneous enoxaparin (40 mg) results in subprophylactic aFXa levels in the majority of cardiac surgery patients.
• These findings suggest that current enoxaparin dosing may be insufficient for effective VTE prophylaxis in this population.
• Further research is needed to determine the clinical implications and optimize VTE prevention strategies.