A Prospective Assessment of Adherence and Persistence to Oral Anticoagulation in Ischemic Stroke Patients With Atrial Fibrillation: Incidence, Predictors and the Prognostic Role of the SAMe-TT2R2 Score.

Patients with ischemic stroke and atrial fibrillation (AF) have a high risk of stroke recurrence, which is the highest among all other pathogenetic subtypes of stroke. This risk is substantially reduced with anticoagulant treatment. For many decades, vitamin-K antagonists (VKA) were the only anticoagulant choice for these patients. However, a number of limitations such as narrow therapeutic window, need for frequent INR measurements and consequent dose adjustments, risk of haemorrhagic complications, food-drug and drug-drug interactions, and others, have undermined the use of anticoagulation by both patients and physicians with apparent influence on the risk of stroke recurrence. During the last decade, four non-vitamin K antagonist oral anticoagulants (NOAC) have been successfully introduced and showed superior safety and efficacy profile than VKAs, more convenient dosing schemes (i.e. no need for adjustments) and minimum interactions with food and drugs. These advantages of NOACs vs. VKAs may have obvious implications to patient adherence to treatment and, consequently, to the efficacy of secondary stroke prevention. Nevertheless, there are only very scarce data available yet that the adherence and persistence to NOACs is higher than the adherence and persistence to VKAs in the specific population of patients with ischemic stroke and atrial fibrillation.

Recently, the SAMe-TT2R2 score has been introduced as a means to identify those AF patients who have inadequate quality of anticoagulation with VKAs expressed as Time within Therapeutic Range (TTR)5. In specific, VKA-anticoagulated AF patients with a SAMe-TT2R2 score of 0-2 are expected to have a TTR >65%, whereas patients with a score of >2 are expected to have lower TTR levels. In this context, one could hypothesize that increased SAMe-TT2R2 score may be associated with inadequate adherence and persistence to VKAs. Other parameters associated with inadequate adherence and persistence in the general AF population include education, employment, social status, and cognitive function. However, this is not well investigated in the specific population of patients with previous stroke where other conditions such as age and functional neurological status may also play an important role in adherence and persistence.