Time in Therapeutic Range (TTR), defined as the time period during which patients have an International Normalized Ratio (INR) within the target interval, represents an interested tool assessing anticoagulation quality with Vitamin K Antagonists (VKA).

We sought to evaluate the quality of anticoagulation with acenocumarol in patients with atrial fibrillation using TTR.

Sixty consecutive patients with non-valvular atrial fibrillation (AF) requiring oral anticoagulation with acenocumarol were prospectively enrolled. One-year clinical follow-up was performed. In all patients, INR was measured monthly. TTR was calculated according to the Rosendaal method.

The mean age was 65 years±10 years; the sex ratio was 0.5. The mean CHADS2 VASC score was 2.8±1.3, whereas mean HASBLED score was 1.8±0.9. The mean INR was 2.7±0.5. INR>4.5 was only observed in 1.7% measurement, while no INR<1.5 was observed. The mean TTR was 53±16%; and 2/3 of patients had a mean TTR<60%. Neither bleeding nor thrombotic events were noticed.

Anticoagulation control needs to be improved in patients with AF on VKA. These results are informative for all stakeholders: patients, health care professionals, and policymakers.