Objective Early following mechanical heart valve replacement, patients are at high risk of valve thrombosis and bleeding complications. There are no published guidelines on the use of specific bridging therapies until full warfarinisation is achieved. Use of unfractionated heparin (UFH) in these patients is widespread. We set out to examine the rate of thrombosis shortly after surgery until full anticoagulation was achieved in patients receiving low molecular weight heparin (LMWH).
Methods Prospectively collected data on 765 patients who had mechanical aortic or mitral valve replacement from January 2002 to September 2011 was reviewed. Of these patients 182 received intravenous or subcutaneous UFH due to co-morbidities and were excluded from our analysis. The remaining patients received 5000 units of Dalteparin (Pfizer) twice daily from the first postoperative day. Post operative echocardiography results were examined for valve thrombosis, and evidence of gastrointestinal or intracranial bleeds was sought. Anticoagulation was deemed therapeutic when the INR was >2.0.
Results 583 patients who had mechanical aortic or mitral valve replacement at our unit from January 2002 to September 2011 were included. These consisted of 451 aortic and 173 mitral valves. 59 patients had multiple valves replaced, including concomitant tricuspid replacement. 385 (66%) patients were male, the mean age was 56 years. There were 4 in-hospital deaths (0.69%). Mean time to reach therapeutic INR was 3.4 days. 18 (3.1%) patients had resternotomy for bleeding. No patients had evidence of valve thrombosis. There were no intracranial bleeds.
Conclusion Use of LMWH compares favourably with published series of bridging with UFH. There was a low incidence of postoperative bleeding complications and no evidence of valve thrombosis. Use of standardised dose of LMWH simplifies administration and there is no need for monitoring of the activated partial thromboplastin time.
- Valvular disease