Is it safe and effective to reduce the target anticoagulation range for patients with mechanical prosthetic aortic valves?

Abstract

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Is it safe and effective to reduce the target anticoagulation range for patients with mechanical aortic valves?' Altogether 922 papers were found using the reported search, of which 7 represented the best evidence to answer the clinical question. Only studies that compared high (target international normalized ratio 2-3) versus low (target international normalized ratio <2-3) intensity anticoagulation were included. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that there is growing evidence for the reduction of the target anticoagulation range for patients with mechanical prosthetic aortic valves, especially bileaflet valves with presumed better haemodynamic properties. Several large randomized controlled trials and a meta-analysis have concluded that reducing the target international normalized ratio range (below the conventional range of 2-3) for mechanical aortic valves in patients with no thrombogenic risk factors produces less bleeding and does not increase thromboembolic events.

Keywords: Anticoagulation; Haemorrhage; International normalized ratio; Mechanical prosthetic aortic valve; Review; Thromboembolism; Warfarin.