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Quality of Warfarin Control and Events in Patients with Mechanical Heart Valves

Grzymala-Lubanski et al report a retrospective non-randomized multicenter cohort study of patients with mechanical heart valves to assess the relationship between the quality and intensity of warfarin therapy and outcomes (thrombosis/bleeding/death). Measures of better quality control were associated with a lower rate of adverse events. Higher intensity anticoagulation was associated with increased rates of bleeding and death.

Two editorials are available here and here.

Abstract

Objectives

To study the impact of time in therapeutic range (TTR) and international normalised ratio (INR)variability on the risk of thromboembolic events, major
bleeding complications and death after mechanical heart valve (MHV)implantation. Additionally, the importance of different target INR levels was elucidated.

Methods

A retrospective, non-randomised multicentre cohort study including all patients with mechanical heart valve (MVH) prosthesis registered in the Swedish
National Quality Registry Auricula from 2006 to 2011. Data were merged with the Swedish National Patient Registry, SWEDEHEART and Cause of Death Registry.

Results

In total 4687 ordination periods,corresponding to 18 022 patient-years on warfarin, were included. High INR variability (above mean ≥0.40) or lower TTR (≤70%) was associated with a higher risk of bleeding (rate per 100 years 4.33 (95% CI 3.87 to 4.82) vs 2.08 (1.78 to 2.41); HR 2.15 (1.75 to 2.61) and
5.13 (4.51 to 5.82) vs 2.30 (2.03 to 2.60); HR 2.43 (2.02 to 2.89)), espectively. High variability and low TTR combined was associated with an even higher risk of bleedings (rate per 100 years 4.12 (95% CI 3.68 to 4.51) vs 2.02 (1.71 to 2.30); HR 2.16 (1.71 to 2.58) and 4.99 (4.38 to 5.52) vs 2.36 (2.06 to 2.60); HR 2.38 (2.05 to 2.85)) compared with the best group. Higher treatment intensity (mean INR 2.8–3.2 vs 2.2–2.7) was associated with higher rate of bleedings (2.92 (2.39 to 3.47) vs 2.48 (2.21 to 2.77); HR 1.29 (1.06 to 1.58)), death (3.36 (2.79 to 4.02) vs 1.89 (1.64 to 2.17), HR 1.65 (1.31 to 2.06)) and
complications in total (6.61 (5.74 to 7.46) vs 5.65 (5.20to 6.06); HR 1.24 (1.06 to 1.41)) after adjustment for MHV position, age and comorbidity.

Conclusions

A high warfarin treatment quality improves outcome after MHV implantation, both
measured with TTR and INR variability. No benefit was found with higher treatment intensity (mean INR 2.8–3.2 vs 2.2–2.7).

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Journal Club 18 September 2013

September 18, 2013 Leave a comment

Paper

Dabigatran versus Warfarin in Patients with Mechanical Heart Valves

Presenter

LAM

Summary

Background

Dabigatran is an oral direct thrombin inhibitor that has been shown to be an effective
alternative to warfarin in patients with atrial fibrillation. We evaluated the use
of dabigatran in patients with mechanical heart valves.

Methods

In this phase 2 dose-validation study, we studied two populations of patients: those
who had undergone aortic- or mitral-valve replacement within the past 7 days and
those who had undergone such replacement at least 3 months earlier. Patients were
randomly assigned in a 2:1 ratio to receive either dabigatran or warfarin. The selection
of the initial dabigatran dose (150, 220, or 300 mg twice daily) was based on
kidney function. Doses were adjusted to obtain a trough plasma level of at least
50 ng per milliliter. The warfarin dose was adjusted to obtain an international normalized
ratio of 2 to 3 or 2.5 to 3.5 on the basis of thromboembolic risk. The primary end
point was the trough plasma level of dabigatran.

Results

The trial was terminated prematurely after the enrollment of 252 patients because
of an excess of thromboembolic and bleeding events among patients in the dabigatran
group. In the as-treated analysis, dose adjustment or discontinuation of
dabigatran was required in 52 of 162 patients (32%). Ischemic or unspecified stroke
occurred in 9 patients (5%) in the dabigatran group and in no patients in the warfarin
group; major bleeding occurred in 7 patients (4%) and 2 patients (2%), respectively.
All patients with major bleeding had pericardial bleeding.

Conclusions

The use of dabigatran in patients with mechanical heart valves was associated with
increased rates of thromboembolic and bleeding complications, as compared with
warfarin, thus showing no benefit and an excess risk.

Further Material

The editorial is here. The supplementary appendix is here

Anticoagulation for pregnant women with prosthetic mechanical heart valves

The management of the pregnant patient with valvular heart disease and in particular mechanical prosthetic valve(s) is a complex and specialized discipline. There are only limited cohorts to guide management.

De Santo present a the outcomes of a low dose oral anticoagulant regimen  in the setting of mechanical aortic valve prosthesis and pre-operative counselling in young women planning on pregnancy. This is a small study (understandably) and highly selective group.

A very useful editorial discussed the paper in the overall context. The  following  graphic is an excerpt.

Anticoagulation regimens for pregnant women with mechanical prosthetic heart valves