Standard versus low-level anticoagulation combined to low-dose dipyridamole after mitral valve replacement
Introduction
In patients with mechanical cardiac valves, our standard anticoagulation policy was to target an INR between 2.5 and 3.5. Studies of long-term oral anticoagulant therapy have shown that this regimen was as effective as, but safer than, a more intensive therapy 1, 2, 3, 4. However, reports have suggested that a lower INR between 2 and 2.5 combined to 300 mg dipyridamole offered a safe antithrombotic therapy to patients with bileaflet St Jude valve 5, 6, 7, 8, 9. Even though the use of combined therapy has been largely limited by the occurrence of intractable headache, dizziness, nausea, flushing and other dipyridamole-related side effects 4, 5. In order to overcome these side effects, we have used the generally tolerable 225 mg daily dose in combination with the suggested low-level anticoagulation regimen. This study was designed to compare the long-term safety and efficacy of such a combined therapy to our standard anticoagulation policy, which is applied in young rheumatic patients with St Jude mitral valve prosthesis.
Section snippets
Methods
Between January 1990 and December 1998, 486 rheumatic patients benefited from mitral valve replacement with St Jude Medical valve prosthesis. The patient criteria was: young patients ≤21 yr of age, of both sexes, have rheumatic mitral valve disease, with or without tricuspid valve incompetence and operated upon electively for first time mitral valve replacement. We excluded from this study, 51 patients who died during the hospital period (9.5%) from causes unrelated to a prosthetic valve or
Results
With the exception of a significantly larger left atrial diameter in patients on low-level combined therapy, both groups were comparable with respect to baseline characteristics (Table 1). Follow-up ranged from 1 to 8 yr, with a mean duration of 3.6±2.1 yr and a cumulative follow-up period of 1712.5 pt yr (1002.8 pt yr in standard monotherapy group and 709.7 pt yr in low-level combined therapy group). Sixteen patients (13 patients on standard monotherapy and three patients on low-level combined
Discussion
The pathophysiologic importance of platelet activation in thrombus formation and the increased platelet consumption in anticoagulated patients with prosthetic cardiac valves 11, 12have led to the clinical evaluation of a combined therapy with warfarin and dipyridamole. As early as 1969, a leading comparative prospective randomized trial has demonstrated that such a combination significantly decreased embolic events after cardiac valve replacement by 92% [13]. Similar trials were carried out on
Acknowledgements
This research was supported by a National Research Center grant (11/3/3/5/1/1998).
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