Low molecular weight heparin after mechanical heart valve replacement

Area of Science:

• Cardiovascular Medicine
• Pharmacology
• Hematology

Background:

• Mechanical heart valves necessitate lifelong anticoagulation therapy for patients.
• This study investigates low molecular weight heparin (LMWH) as an alternative anticoagulation method post-mechanical heart valve replacement.

Purpose of the Study:

• To compare the efficacy and safety of low molecular weight heparin (LMWH) versus unfractionated heparin (UH) in patients with mechanical heart valves.
• To assess the feasibility and biological anticoagulation provided by LMWH in this patient population.

Main Methods:

• A comparative, nonrandomized study involving 208 consecutive patients undergoing mechanical heart valve replacement.
• Patients were anticoagulated with either unfractionated heparin (UH) (n=106) or low molecular weight heparin (LMWH) (n=102).
• Therapeutic ranges were monitored using activated partial-thromboplastin time (aPTT) for UH and anti-Xa activity for LMWH.

Main Results:

• LMWH achieved therapeutic anti-Xa activity in 87% of patients on day two, significantly higher than UH's 9% therapeutic aPTT.
• On the last day, all LMWH patients maintained adequate anti-Xa levels, while 62% of UH patients were over-anticoagulated.
• Bleeding events were similar between groups (two major in each), with one stroke in the UH group.

Conclusions:

• Anticoagulation with LMWH after mechanical heart valve replacement is feasible and provides adequate biological anticoagulation.
• LMWH demonstrates a favorable comparison to UH in this initial study.
• Randomized controlled trials are warranted to further validate LMWH as a therapeutic option.