Prolonged heparin and vitamin K antagonist regimen for early non-obstructive thrombosis of mechanical mitral valve prostheses.

Background and Aim of the Study: Transesophageal echocardiography (TEE) has been used to document the incidence of non-obstructive thrombosis (NOT) after mechanical prosthetic mitral valve replacement (MVR). The postoperative occurrence and unpredictable evolution of NOT complicate its management. The study aim was to examine the safety and efficacy of prolonged, combined administration of heparin and vitamin K antagonists (VKA) recommended for this indication.
Methods: All patients who underwent mechanical prosthetic MVR between July 1999 and December 2004 at the authors' institution were systematically studied with TEE immediately after surgery. Patients who presented with > or = 5 mm NOT were treated with combined heparin and VKA until TEE-confirmed resolution of the thrombus.
Results: Among 256 patients who underwent 263 MVRs (seven reinterventions), 47 (17.9%) presenting with > or = 5 mm NOT received combined heparin and VKA for between 7 and 115 days (median 17 days). No thromboembolic or hemorrhagic events or deaths were observed during this period of observation. Four patients were treated with danaparoid and VKA because of thrombocytopenia induced by heparin before the diagnosis of NOT. Over a mean follow up of 39 months, one patient died from cancer and another from the sequelae of a stroke. In total, there were five NOT recurrences, three of which were complicated by embolic events without sequelae within eight months, and one by a recurrent stroke. In addition, three patients without demonstrable NOT recurrence suffered transient ischemic attacks.
Conclusion: Among this small sample of patients, combined heparin and VKA was well tolerated and effective, and could prevent reoperation or thrombolysis. These observations may warrant further study in a larger patient population.