Inadequacy of Vitamin K Antagonist Use in Patients with Atrial Fibrillation – Overview of Everyday Clinical Practice at the Merkur University Hospital in Zagreb, Croatia

Atrial fibrillation is the most common cardiac arrhythmia. It increases the risk of death and thromboembolic events. Vitamin K antagonists reduce these risks. Disadvantages of vitamin K antagonist therapy are narrow therapeutic range and interactions with drugs and food. In a single center prospective study, we enrolled 249 patients with atrial fibrillation over a 12-month period. The aim of our study was to evaluate vitamin K antagonist use regarding the indication and adequate dose. Data on 249 consecutive patients with atrial fibrillation were collected before general availability of novel oral anticoagulants. Out of 249 patients, 160 (64.2%) had indication for oral anticoagulant therapy. Only 81 (50.6%) patients had vitamin K antagonist in therapy, 12 (14.8%) of them in adequate dose. We also analyzed 129 patients aged over 75, of which 109 (84.4%) had absolute indication for oral anticoagulant therapy. Only 34 (31.2%) patients aged over 75 had been receiving vitamin K antagonist therapy and 6 (17.6%) had the International Normalized Ratio values within the proposed therapeutic interval. We found a significantly higher rate of anticoagulant therapy introduction in patients under 75 years (p=0.03), but there were no significant differences in the adequacy of anticoagulant therapy (p=0.89) between these two populations. Our results showed clear inadequacies of vitamin K antagonist treatment with a growing need for a wider use of novel oral anticoagulants.
Atrijska fibrilacija je najučestalija aritmija koja povećava rizik smrti i tromboembolijskih incidenata. Antagonisti vitamina K smanjuju taj rizik. Problem terapije s antagonistima vitamina K je uska terapijska širina i brojne interakcije s lijekovima i hranom. Cilj ovoga istraživanja bio je utvrditi dostatnost primjene antagonista vitamina K s obzirom na indikaciju i dozu. Prikupljeni su podaci 249 bolesnika s atrijskom fibrilacijom hospitaliziranih u Kliničkoj bolnici “Merkur” u razdoblju od 12 mjeseci i to prije šire dostupnosti novijih oralnih antiokoagulansa. Od svih bolesnika, 160 (64,2%) ih je imalo indikaciju za primjenu oralne antikoagulantne terapije, a tek je njih 81 (50,6%) imalo antagonist vitamina K u terapiji. Samo 12 (14,8%) bolesnika je uzimalo antagonist vitamina K u dostatnoj dozi, a 129 (51,8%) ih je bilo iznad 75 godina starosti. Njih 109 (84,4%) je imalo indikaciju za oralnu antikoagulantnu terapiju, a samo 34 (31,2%) ih je uzimalo antagonist vitamina K, od kojih je 6 (17,6%) imalo INR u terapijskim vrijednostima. Statistička analiza podataka pokazala je da su bolesnici mlađi od 75 godina češće uzimali indiciranu oralnu antikoagulantnu terapiju u odnosu na bolesnike starije od 75 godina (p=0,03), dok nije bilo statistički značajne razlike u dostatnoj primjeni antikoagulantne terapije između ovih dviju populacija (p=0,89). Naši rezultati jasno pokazuju nedostatnosti primjene antagonista vitamina K kao i potrebu bržeg prijelaza prema terapiji novijim oralnim antikoagulansima.