Is low anticoagulation intensity more beneficial for patients with bileaflet mechanical mitral valves? A meta-analysis.

For the mitral valve replacement (MVR) using the lowest thrombogenic risk bileaflet valves (St. Jude Medical [St Paul, MN, USA], Carbomedics [Austin, TX, USA] and On-X [Austin, TX, USA]), excellent results can be achieved by adopting the anticoagulation intensity (median INR<2.5) which is lower than the recommended intensity (INR:2.5~3.5). Our aim was to provide a pooled estimate of potential benefit from clinical studies using low anticoagulation intensity and high intensity in these patients.Relevant studies published before February 2014 were searched through a number of digital databases (MEDLINE, EMBASE, Cochrane Library, etc.). They were pooled by SPSS19.0 using the random effect method in three fields: occurrence rate of major thromboembolism, major hemorrhage and major total events. Fourteen studies with 3595 patients were included. The follow-up period was 12,846.6 patient-years.Pooled estimates indicated reduction in major hemorrhage (RR:0.420, 95%CI: 0.296~0.595, P<0.001) and major total events (RR: 0.738, 95%CI: 0.604~0.902, P=0.003) in the low intensity group. No difference was noted in major thromboembolism (RR: 1.045, 95%CI: 0.814~1.341, P=0.75).Compared with the recommended high intensity, low anticoagulation intensity (median INR<2.5) may be more beneficial for the MVR patients using the lowest thrombogenic risk bileaflet valves. We recommended an INR between 2.0 and 2.5, with a median INR of 2.3 for these MVR patients.