Plasma Warfarin Level and International Normalized Ratio do not Correlate with Bleeding Events in Indonesian Patients of Minangkabau Ethnicity with Atrial Fibrillation

  • Rahmatini Rahmatini Department of Pharmacology and Therapeutics, Faculty of Medicine, Andalas University, Padang, West Sumatera, Indonesia
  • Gestina Aliska Department of Pharmacology and Therapeutics, Faculty of Medicine, Andalas University, Padang, West Sumatera, Indonesia
  • Elly Usman Department of Pharmacology and Therapeutics, Faculty of Medicine, Andalas University, Padang, West Sumatera, Indonesia
  • Mefri Yanni Department of Cardiology and Vascular Medicine, Faculty of Medicine, Andalas University, Padang, West Sumatera, Indonesia
  • Cimi Ilmiawati Department of Pharmacology and Therapeutics, Faculty of Medicine, Andalas University, Padang, West Sumatera, Indonesia
Keywords: Atrial fibrillation, Indonesian, International normalized ratio, Thromboembolism, Warfarin


BACKGROUND: Warfarin is the mainstay of anticoagulant therapy to prevent thromboembolism in atrial fibrillation (AF). It has a narrow therapeutic window, rendering monitoring prothrombin time necessary using the international normalized ratio (INR). However, INR value is not always correlated with the clinical risk of bleeding.

AIM: We aimed to monitor plasma warfarin concentration and to analyze its correlation with bleeding events in Indonesian patients of Minangkabau ethnicity with AF.

METHODS: We consecutively recruited outpatients with AF from January to November 2017 at a tertiary hospital in West Sumatera, Indonesia. At the time of the study, patients had received at least 5 weeks of warfarin. Their characteristics were obtained from medical records, and INR data were collected. Warfarin plasma concentration was analyzed using high-performance liquid chromatography.

RESULTS: There were a total of 45 patients (25 males and 20 females; mean age 54.6 years). The number of patients with INR value lower than, within, and higher than target value (2.0–3.0) was 25, 12, and 8, respectively. Half of the patients (n = 23; 51.1%) had subtherapeutic plasma warfarin levels and nearly half (n = 20; 44.4%) of the patients had therapeutic plasma warfarin levels. INR value was not significantly correlated with plasma warfarin level (r = 0.273; p = 0.07). Bleeding events occurred in 14 patients. INR value was not significantly different (p = 0.12), while the plasma warfarin level was marginally significantly different (p = 0.05) between those with bleeding and no bleeding events.

CONCLUSION: Neither warfarin plasma concentration nor INR was correlated with bleeding events in Indonesian patients of Minangkabau ethnicity with AF.


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How to Cite
Rahmatini R, Aliska G, Usman E, Yanni M, Ilmiawati C. Plasma Warfarin Level and International Normalized Ratio do not Correlate with Bleeding Events in Indonesian Patients of Minangkabau Ethnicity with Atrial Fibrillation. Open Access Maced J Med Sci [Internet]. 2020Apr.27 [cited 2020Oct.31];8(B):192-7. Available from: