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Therapeutic comparison between phenprocoumon and warfarin in patients bearing mechanical valvar prostheses and in atrial fibrillation

Grant number: 19/21190-9
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): October 01, 2019
Effective date (End): September 30, 2020
Field of knowledge:Health Sciences - Medicine - Medical Clinics
Principal Investigator:Fausto Feres
Grantee:Isabella Seno Coelho
Home Institution: Instituto Dante Pazzanese de Cardiologia (IDPC). Fundação Adib Jatene (FAJ). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil


Rationality: It is a worldwide consensus that patients with mechanical valve prostheses, especially in the presence of atrial fibrillation (AF), have high risks of thromboembolic events. Antithrombotic prevention is recommended, especially with vitamin K antagonists (AVK). Warfarin is the only FDA approved VKA being used in North America and the United Kingdom. While phenprocoumon is mainly used in European countries, such as Germany and the Netherlands, and in Brazil. In 2018, commercialization of phenprocoumon was discontinued in Brazil, requiring replacement of the warfarin regimen. The success of antithrombotic therapy depends on several factors, including knowledge of drug interactions, adherence to medication schedules, dietary care, and regular INR laboratory controls. Rationale: Towards medication discontinuation, the new challenge for thousands of Brazilians is the adaptation to warfarin use after years of treatment with phenprocoumon. Although both are coumarin derivatives, they have different pharmacokinetics, presenting variations in the therapeutic range5. Therefore, a study is necessary to analyze if these patients were able to normalize their therapeutic ranges after the change of medications. Objective: In this project, by analyzing the mean follow-up with phenprocoumon versus mean follow-up with warfarin of patients from the anticoagulation sector of the Dante Pazzanese Institute of Cardiology, we can create an algorithm for drug alternation. Thus, reaching the target dose early during the medication transition phase and preventing adverse events, whether thromboembolic or hemorrhagic. Methods: This is an observational, prospective study through active research in medical records of patients followed in the Oral Anticoagulation Sector, in the Clinical Valve Diseases Section of the Dante Pazzanese Institute of Cardiology (IDPC), from January 2019 to January 2020. Patients with mechanical valve prosthesis using vitamin K antagonists (warfarin or phenprocoumon), patients with valvular and non-valvular fibrillation or atrial flutter with indication for oral anticoagulants (CHA2DS2VASc score e 2) with a free and informed consent form signed. Pregnant patients, patients who permanently discontinued oral anticoagulation or patients under 18 years of age were excluded from the analyzes. Expected Results: 1,000 patients with mechanical valve prostheses and 1,000 patients with valvular and non-valvular atrial fibrillation or atrial flutter with indication for the use of vitamin K antagonists will be evaluated. The sample size will be for convenience to reflect clinical practice. and provide reliable, accurate and robust information. Within one year of clinical follow-up 3,5% of deaths, 1,3% of thromboembolic events and 2% of hemorrhagic events are expected, and from this project we will analyze whether these rates are above or below expectations. In addition to creating the phenprocoumon-warfarin transition algorithm.