Assessment of Oral Anticoagulation with Vitamin K Antagonists in Patients Living in a Low-Income Country of West Africa

Introduction: Despite the rise of direct oral anticoagulants (DOACs), vitamin K antagonists (VKA) remain the most widely used oral anticoagulants in developing countries. The aim of this study was to estimate the prevalence of good anticoagulation in patients treated with VKA in Lomé and describe associated factors. Methods: This was a cross-sectional study conducted from November 2019 to October 2020 in the cardiology departments of two University teaching hospitals in Lomé (CHU Sylvanus Olympio and CHU Campus), involving patients on VKA for ≥3 months, with a target international normalized ratio (INR) of 2.5 and a therapeutic margin between 2 and 3. The quality of anticoagulation was assessed by the time in therapeutic range (TTR) which was assessed by the Rosendaal method. Good anticoagulation was defined by a TTR > 70%. Results: A total of 344 patients were included (mean age = 58 ± 13.8 years, women = 56.1%). Indications for VKA treatment were represented by venous thromboembolic disease (43.3%), supraventricular arrhythmia (28.2%), severe left ventricular systolic dysfunction (19.8%) and pulmonary hypertension (8.7%). The average TTR was 47.6 ± 20.8%. The rate of good anticoagulation was 17.7%. Factors associated with good anticoagulation were the use of fluindione vs acenocoumarol (OR = 11.17;95% CI: 3.2 - 39.6;p = 0.0002), concomitant low-dose aspirin (OR 4.44;95% CI: 1.4 - 13.9;p = 0.01) and INR monitoring exclusively by the patient himself (OR = 4.92;95% CI: 1.5 - 16.3;p = 0.008). The rate of thromboembolic and hemorrhagic complications was each 2.6% and was not correlated with the quality of anticoagulation. Quality of anticoagulation by VKAs was poor in our practice. Factors associated with good anticoagulation were the use of fluindione vs acenocoumarol, concomitant low-dose aspirin and monitoring of INR exclusively by the patient himself. Conclusion: The quality of oral anticoagulation by VKAs could be improved in our practice by the creation of anticoagulation clinics for better therapeutic education of patients and efficient management of VKA dose, and the use of prescription assistance software.

The risk of bleeding of triple therapy with vitamin K-antagonists,aspirin and clopidogrel after coronary stent implantation:Facts and questions

Background Triple therapy(TT)with vitamin K-antagonists(VKA),aspirin and clopidogrel is the recommended antithrombotic treatment following percutaneous coronary intervention with stent implantation(PCI-S)in patients with an indication for oral anticoagulation.TT is associated with an increased risk of bleeding,but available evidence is flawed by important limitations,including the limited size and the retrospective design of most of the studies,as well as the rare reporting of the incidence of in-hospital bleeding and the treatment which was actually ongoing at the time of bleeding.Since the perceived high bleeding risk of TT may deny patients effective strategies,the determination of the true safety profile of TT is of paramount importance.Methods All the 27 published studies where the incidence of bleeding at various time points during follow-up has been reported separately for patients on TT were reviewed,and the weakness of the data was analyzed.Results The absolute incidence of major bleeding upon discharge at in-hospital,≤1 month,6 months,12 months and≥12 months was:3.3%±1.9%,5.1%±6.7%,8.0%±5.2%,9.0%±8.0,and 6.2%±7.8%,respectively,and not substantially different from that observed in previous studies with prolonged dual antiplatelet treatment with aspirin and clopidogrel.Conclusions While waiting for the ongoing,large-scale,registries and clinical trials to clarify the few facts and to answer the many questions regarding the risk of bleeding of TT,this treatment should not be denied to patients with an indication for VKA undergoing PCI-S provided that the proper measures and cautions are implemented.