Early postoperative anticoagulation after mechanical valve replacement: a Canadian survey

The optimal approach to anticoagulation during the early postoperative period after mechanical valve replacement, by which early thromboembolism is prevented without bleeding complications, is not yet known. The study aim was to examine the practice patterns of Canadian cardiac surgeons with regard to early postoperative anticoagulation after mechanical valve implantation.

A questionnaire was sent to 100 Canadian cardiac surgeons in July 2004, and 57 responses were received. Data were collected regarding the approaches to early postoperative anticoagulation following uncomplicated isolated mechanical aortic valve replacement (AVR) and mitral valve replacement (MVR).

Heparin was administered routinely after AVR and MVR by 63% and 68% of surgeons, respectively. This was most commonly initiated on postoperative day (POD) 1, and given either subcutaneously (AVR, 28%; MVR, 25%) or intravenously (AVR, 33%; MVR, 42%). Alternatively, low-molecular-weight heparin was used by 21% and 23% of surgeons after AVR and MVR, respectively. Oral warfarin was usually started on POD 1 (72% and 68%, respectively), with 40% prescribing an initial dose between 2.5 and 5.0 mg, and 51% administering between 5.1 and 7.5 mg. When heparin was not used, oral anticoagulation was more often administered earlier (AVR, p = 0.003; MVR, p = 0.006), but not at higher doses (AVR, p = 0.07; MVR, p = 0.2). Following surgery, aspirin was prescribed by 61% and 65% of surgeons after AVR and MVR, respectively.

The study results highlighted a significant variability in the management of early postoperative anticoagulation after mechanical valve implantation. The clinical impact of these findings is unknown, and can only be assessed through a prospective trial.