Background:
Vitamin K antagonists ( VKA ) remain a viable oral anticoagulant ( OAC ) for many patients because of its availability and cost. The aim of the study was to assess the quality of VKA control in patients with atrial fibrillation and the influence of quality of VKA control on in-hospital mortality.

Material and methods:
We retrospectively studied 907 patients with atrial fibrillation (AF).

Results:
A total of 422 patients with AF on VKA ( male 59 %; mean age 71 ± 10 years) were included in the analysis. Of the total International Normalized Ratio (INR) values, 33% were in the therapeutic range of 2.0–3.0, 46 % were below, and 21% were above this range. Patients with INR < 2 had more frequently a history of systemic embolism (6% vs 2%; p=0.04). In multivariate logistic regression model, odds of INR < 2 was higher in patients with history of systemic embolism (OR = 2.95; 95 %CI: 1.01-8.59; p=0.05). INR control did not differ between patients with and without a history of stroke ( 29% vs 33%, p=0.7). In patients with AF and history of stroke in-hospital mortality was significantly higher (8% vs 2%; p = 0.04).

Conclusions:
Among patients with AF chronic anticoagulant therapy with VKA is suboptimal. Unfortunately, history of ischemic stroke did not cause better INR control. Patients with a history of systemic embolism and very high risk for thromboembolic complications had more often INR below the therapeutic range than the rest of the patients with AF.