Harris JR, Hatch R, Vallabhajosyula P, Lo Y, Mowery D, Patel N. AM Versus PM Postoperative Administration of Warfarin With a Mechanical Mitral Valve.
J Pharm Technol 2021;
37:89-94. [PMID:
34752556 DOI:
10.1177/8755122520973613]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: Currently, there are no guidelines regarding the optimal daily timing of inpatient warfarin administration. Objective: The purpose of this study was to determine whether dosing warfarin in the morning will have a significant impact on therapeutic international normalized ratio (INR) achievement compared with evening administration in mechanical mitral valve patients initiated on warfarin following cardiac surgery. Methods: This was a single-center, pre- and post-retrospective cohort conducted between 2014 and 2018. One-hundred fifty-four adult patients who underwent a mechanical mitral valve replacement or alternative cardiac surgery with a history of a mechanical mitral valve were enrolled. The primary outcome was achievement of therapeutic INR at any time point after initiation of warfarin. Pre-intervention administration timing was 6 pm and post-intervention timing was 10 am. Results: Baseline characteristics including age, sex, and race were similar between the 2 groups (P = NS for each characteristic). Therapeutic INR achievement was significantly improved at all time points following 10 am warfarin administration compared with 6 pm (hazard ratio = 1.69; P = .005). Mean time-to-therapeutic INR was 7.37 days in the post-intervention group and 8.39 days in the pre-intervention group (P = .073). There were no significant differences in INR >4, bleeding, or thrombotic complications between groups. Conclusion and Relevance: This retrospective analysis suggests that there may be a postoperative benefit in therapeutic INR achievement in mechanical valve patients when dosing warfarin in the morning compared with evening administration. Large-scale studies should be conducted to further elucidate the potential benefit across more heterogeneous populations.
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