Methods for detection of direct oral anticoagulants and their role in clinical practice

Introduction: Atrial fi brillation (AF) is the most common arrhythmia that increases by age, doubles for every decade after age of 50 years and reaches about 10% patients ≥ 80 years.¹ Despite direct oral anticoagulants' (DOACs') predictable pharmacokinetics and pharmacodynamics, the laboratory tests are necessary for efective and safe medical treatment, also for prediction and detection of thrombotic and bleeding events, as well as in situations when temporary discontinuation could be desirable.² Aim: The aim of this study was to identify and analyze the need of coagulation tests for AF patients with high cardiovascular risk in clinical practice. Methods: Quantitative, analytic, cross-sectional clinical trial, during the period from October 2016 till June 2017, was performed at Center of Cardiology, Pauls Stradins Clinical University Hospital, Latvia. There were collected data about patients with non-valvular AF, under anticoagulative therapy ≥3 months, defi ned as a high-risk group by CHA₂DS₂-VASc score - more or equal to 2 or 3, men and women, respectively. Data were analyzed using SPSS. Results: There were collected data about 143 patients of whom 46.2% (n = 66) were male; the mean age was 69.7 (SD ± 9.9) years. About 2/3 (73.1%) of all patients the AF were longer than 1 year. The mean CHA₂DS₂-VASc score was 4.2 (SD ± 1.5). The most common comorbidities were arterial hypertension (65.0%; 93), chronic heart failure (48.3%; 69), coronary artery disease (32.9%; 47), diabetes mellitus (24.5%; 35), and dyslipidemia (25.9%; 37). Almost half of patients (46.2%; 66) used DOACs, 31.5% rivaroxaban and 14.7% dabigatran, respectively; furthermore, 1.4% patients used DOACs with antiaggregants. 49.7% (71) patients had increased risk of possible drug-drug interactions, most frequently with proton pump inhibitors (16.8%; 24), amiodarone (24.5%; 35), anti-inflammatory drugs (49.0%; 70). The use of DOACs and possible drug-drug interactions increases by risk score, reaching the maximum score 3 (16.1%; 23) and the mean frequent score 4.4 of 86 (60.1%) AF patients, respectively. The drug concentration in blood was lower than expected, reaching about 75.20% of C_max. Conclusion: DOACs' usage correlates with CHA₂DS₂-VASc score with mean frequent score 4.4 of 86 (60.1%) AF patients, respectively. Coagulation tests were applicable more than half of patients (60.1%) to detect DOACs concentration in plasma.