Why the study?
Increased warfarin sensitivity after mechanical mitral valve replacement dictates clinical discretion, but evidence is lacking regarding optimal warfarin initiation dosing in these patients.
Does warfarin initiation at 5 mg improve time to target INR compared to 3 mg in postoperative mechanical mitral valve replacement patients?
Does warfarin initiation at 5 mg improve time to target INR compared to 3 mg in postoperative mechanical mitral valve replacement patients?
Initiating warfarin at 5 mg rather than 3 mg in postoperative mechanical mitral valve replacement patients significantly reduces the time to target INR and the cost of enoxaparin bridging without increasing bleeding events.
Supports 5 mg warfarin initiation to shorten enoxaparin bridging post-mechanical MVR without excess bleeding; confirms optimized dosing in this RCT population.
BACKGROUND: The increased warfarin sensitivity observed after mechanical mitral valve replacement (MVR) operations dictates clinical discretion in warfarin dose initiation. Evidence is still lacking with regard to anticoagulation management of MVR patients. OBJECTIVE: This study aimed to compare initiating warfarin at the recommended dosing regimen versus empirically lowered doses intended to account for the variation in warfarin sensitivity. METHODS: A prospective, single-blind, randomized, comparative study was conducted in postoperative MVR patients. Patients were randomly assigned to either the 5 mg group (n = 25) or the 3 mg group (n = 25) and were initiated on a 5 or 3 mg warfarin dose, respectively. Time to target international normalized ratio (INR), time in therapeutic range, occurrence of bleeding/thromboembolic events, and cost of bridging with enoxaparin were assessed for both groups. RESULTS: Target INR was achieved earlier in the 5 mg group than in the 3 mg group (p = 0.033), with a mean ± SD of 5.3 ± 2.0 and 6.6 ± 2.0, respectively (95% confidence interval of the mean difference 1.022-1.890). Bleeding events did not differ significantly between the two groups. The cost of enoxaparin consumption per patient was significantly higher in the 3 mg group versus the 5 mg group (p = 0.002). CONCLUSIONS: The initiation of warfarin at a 5 mg dose in MVR patients was more efficacious than the 3 mg dose in terms of time to reach the target INR. Moreover, the cost of enoxaparin bridging was significantly reduced with a 5 mg warfarin initiation dose. Bleeding events were comparable. GOV ID: NCT04235569, 22 January 2020.
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Sabry et al. (2022) studied this question.
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