Comparing Usual Care With a Warfarin Initiation Protocol After Mechanical Heart Valve Replacement. (March 2017)

• Record Type: Journal Article
• Authors: Roberts, Gregory; Razooqi, Rasha; Quinn, Stephen
• Is Part Of: Annals of pharmacotherapy. Volume 51:Number 3(2017:Mar.)
• Page Start: 219
• Page End: 225
• Publication Date: 2017-03
• Subjects: warfarin -- anticoagulation -- cardiovascular drugs -- clinical pharmacy -- dosing -- surgery; Chemotherapy -- Periodicals; Pharmacology -- Periodicals; 615.5805
• DOI: 10.1177/1060028016676830
• Languages: English
• ISSNs: 1060-0280

Abstract

Background: The immediate postoperative warfarin sensitivity for patients receiving heart valve prostheses is increased. Established warfarin initiation protocols may lack clinical applicability, resulting in dosing based on clinical judgment.Objective: To compare current practice for warfarin initiation with a known warfarin initiation protocol, with doses proportionally reduced to account for the increased postoperative sensitivity.Methods: We compared the Mechanical Heart Valve Warfarin Initiation Protocol (Protocol group) with current practice (clinical judgment—Empirical group) for patients receiving mechanical heart valves in an observational before-and-after format. End points were the time to achieve a stable therapeutic international normalized ratio (INR), doses held in the first 6 days, and overanticoagulation in the first 6 days.Results: The Protocol group (n = 37) achieved a stable INR more rapidly than the Empirical group (n = 77; median times 5.1 and 8.7 days, respectively; P = 0.002). Multivariable analysis indicated that the Protocol group (hazard ratio [HR] = 2.22; P = 0.005) and men (HR = 1.76; P = 0.043) more rapidly achieved a stable therapeutic INR. Age, serum albumin, amiodarone, presence of severe heart failure, and surgery type had no impact. Protocol patients had fewer doses held (1.1% vs 10.1%, P < 0.001) and no difference in overanticoagulation (2.7% vs 9.1%, P = 0.27).Conclusion: The Mechanical Heart Valve Warfarin Initiation Protocol provided a reliable approach to initiating warfarin in patients receiving mechanical aortic or mitral valves.