Cardiac intraventricular thrombus in protein C deficiency

Mr Nair and his colleagues¹ reported a patient with protein C deficiency who had severe recurrent thromboembolic problems despite anticoagulant therapy. Three points for discussion arise. First, was the dose of warfarin sufficient, given the recurrent thromboses despite treatment? Although the APC ratio was normal, a case could be made for keeping the INR in such patients between 2.5 and 3.5, much as in patients with mechanical cardiac valve prostheses², despite the increased risk of haemorrhage. Second, might there be a second thrombophilia to account for the severe familial thrombotic tendency? Perhaps genotyping for the prothrombin gene mutation or other less frequently recognized thrombophilias should be performed in addition to the factor V Leiden genotyping³, as well as serology testing for cardiolipin antibodies. Finally, the value for plasma homocysteine (88 μmol/L) seems high despite the ‘normal range’ of 50-200: most laboratories quote a normal range for total plasma homocysteine between 5 and 15, depending on age and gender⁴.