Antithrombotic therapy after bioprosthetic aortic valve replacement (AVR) is a debated issue. AVR is a frequent intervention given the high prevalence of aortic stenosis and ageing population. The absence of consensus highlights the need for an evaluation of actual clinical practices.

Antithrombotic therapy was prospectively studied in 434 patients operated on for bioprosthetic AVR between January and April 2011 in 14 French centres. Patients previously treated with vitamin K antagonists (VKA) were excluded. Mean age was 75±9 years, 58% were male and 33% had coronary artery disease. Surgery was performed for aortic stenosis in 87% of cases and was combined with coronary artery bypass grafting (CABG) in 23% of patients.

After initial heparin therapy, in-hospital antithrombotic treatment was : aspirin alone in 65% of cases; VKA alone in 9% of cases; VKA+ aspirin in 19% of cases; and neither VKA nor aspirin in 7% of cases.

Factors that impacted the prescription of VKA were: coronary disease (p<0.001), associated CABG (p<0.007) and post-operative supraventricular arrhythmias (p<0.007). The strongest factor was the centre effect (p<0.0001) (Figure 1). There was no relationship between the prescription of VKA and the occurrence of in-hospital thromboembolic complications (p<0.21) or bleeding (p<0.31).

This multicentre prospective study shows that VKA are prescribed in only 28% of patients after bioprosthetic AVR, despite current recommendations in Europe. Although arrhythmias and coronary disease are determinants of treatment, VKA prescription seems to be more closely related to the centre effect than to patient characteristics. Homogenization of clinical practices is therefore needed and randomized trials would be helpful in this setting.