Fondaparinux bridging successful in mechanical aortic valve patient
MedWire News: Fondaparinux may offer an effective bridging therapy for patients with a mechanical aortic heart valve and a history of heparin-induced thrombocytopenia (HIT), US researchers believe.
Their case report, published in the Journal of Thrombosis and Thrombolysis, describes the successful use of the factor Xa inhibitor in a 36-year-old woman whose warfarin was discontinued after she required emergency surgery.
The patient had been using warfarin anticoagulation for around 2 years following her mechanical aortic valve replacement for infective endocarditis, and had a history of HIT, as well as substance abuse, stroke, myocardial infarction, essential thrombocythemia, aortic aneurysm, and endometriosis.
The patient was admitted to the emergency department with acute renal failure and underwent surgery for a ruptured ovarian cyst and removal of a large organized clot.
Warfarin was withheld and the patient treated with blood transfusions. Fondaparinux 7.5 mg once daily was used as bridging treatment, based on the patient's creatinine level and clearance, and weight. Treatment continued until the patient achieved two consecutive therapeutic International Normalized Ratio (INR) values.
Warfarin was re-initiated 2 days after surgery to a target INR of 2.0-3.0, but after 14 days the patient had not achieved a therapeutic INR.
The patient was checked for fondaparinux accumulation using the anti-factor Xa assay. The woman's trough and peak fondaparinux levels were slightly above the reference ranges, but by this time she had achieved a therapeutic INR and treatment was discontinued.
"While there is currently no literature to support the use of fondaparinux in patients with mechanical heart valves, this drug may offer an option for management of such patients who cannot use heparin products," write Tia Corbett (Sinai-Grace Hospital, Detroit, Michigan) and co-workers.
"However, further clinical investigations are warranted to confirm both the safety and efficacy of this agent in the mechanical heart valve population."
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By Lynda Williams