[Early non-obstructive thrombosis of mechanical mitral valve prostheses]

Transoesophageal echocardiography has shown a high incidence on non-obstructive thrombosis after mitral valve replacement with a mechanical prosthesis. The unpredictable outcome and the period during which the complication arises make treatment difficult. The aim of this study was to assess the tolerance and efficacy of the association of long-term heparin and oral anticoagulation, as recommended in this indication. All patients undergoing mitral valve replacement with a mechanical prosthesis between June 1999 and July 2001 were systematically included and studied by transoesophageal echocardiography in the immediate postoperative period. Those with non-obstructive thrombosis at least 5 mm in size were treated by heparin and oral coagulation until the thrombus disappeared on transoesophageal echocardiography. One hundred and fourteen patients undergoing 120 mitral valve replacements (6 reoperations) underwent transoesophageal echocardiography and non-obstructive thrombi measuring at least 5 mm were found on 26 occasions (21.7%). The association of heparin and oral coagulation was maintained for 7 to 115 days (average 20 days). No thromboembolic or haemorrhagic complications and no deaths were observed during this period. Two patients were treated with danaparoid and oral anticoagulation because of heparin-induced thrombocytopenia before the diagnosis. None of the patients died during follow-up (average 49 months); there were 4 recurrent non-obstructive thromboses, three of which were complicated by thromboembolic events with no sequellae in the first 8 months, again treated effectively with the association of heparin and oral anticoagulants; two cerebral embolic events without sequellae were observed without a demonstrable non-obstructive thrombus on transoesophageal echocardiography. The authors conclude that the association of heparin and oral anticoagulants seems well tolerated and effective in this small population and this would justify a large scale clinical trial.