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Background Vitamin K activates matrix Gla protein (MGP), a key inhibitor of vascular calcification. There is a high prevalence of sub-clinical vitamin K deficiency in patients with end stage kidney disease. Methods A parallel randomized placebo-controlled pilot trial designed to determine whether 10 mg of phylloquinone thrice weekly versus placebo modifies coronary artery calcification progression over 12 months in patients requiring hemodialysis with a coronary artery calcium score (CAC) ≥ 30 Agatston units. (ClinicalTrials.gov identifier NCT01528800). The primary outcome was feasibility (recruitment rate, compliance with study medication, study completion, and adherence overall to study protocol). CAC score was used to assess calcification at baseline and 12 months. Secondary objectives were to explore the impact of phylloquinone on vitamin K-related biomarkers (phylloquinone, dephospho-uncarboxylated MGP and the Gla-osteocalcin to Glu-osteocalcin ratio) and events of clinical interest. Results Eighty-six patients with a CAC score ≥ 30 Agatston units were randomized to either 10 mg of phylloquinone or matching placebo three times per week. Sixty-nine participants (80%) completed the trial. Recruitment rate (4.4 participants/month) and medication compliance (96%) met pre-defined feasibility criteria of ≥ 4.17 and ≥ 90%, respectively. Patients randomized to phylloquinone for 12 months had significantly reduced levels of dephospho-uncarboxylated MGP (86% reduction) and increased levels of phylloquinone and Gla-osteocalcin to Glu-osteocalcin ratio compared to placebo. There was no difference in absolute or relative progression of coronary artery calcification between groups. Conclusion We demonstrated that phylloquinone treatment improves vitamin K status and that a fully powered randomized trial may be feasible.

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