November 2, 2018PLoS ONEOpen Access

Antithrombotic treatments in patients with acute ischemic stroke and non-valvular atrial fibrillation before introduction of non-vitamin K antagonist oral anticoagulants into practice in Korea

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Why the study?

Does well-controlled INR improve the composite of stroke recurrence, major bleeding, and death compared to poorly-controlled INR in patients with acute ischemic stroke and non-valvular atrial fibrillation?

Structured PICO

Population

1,350 patients with acute ischemic stroke (AIS) and non-valvular atrial fibrillation (NVAF) discharged no later than 2008 in Korea

Intervention

Long-term antithrombotic treatment patterns, specifically Vitamin K antagonist (VKA) therapy with well-controlled INR (modified TTR ≥47.0%)

Comparator

Other antithrombotic treatment patterns, specifically VKA therapy with poorly-controlled INR (modified TTR <47.0%) or discontinuation of therapy

Outcome

Composite of stroke recurrence, major bleeding, and death at 3 years of follow-upcomposite

In the pre-NOAC era, poor INR control and discontinuation of antithrombotic therapy were associated with significantly higher rates of stroke recurrence, major bleeding, and death in patients with NVAF and acute ischemic stroke.

Implication

VKA discontinuation and poor INR control were associated with higher composite events; leaves open optimal long-term strategies in the NOAC era.

Abstract

BACKGROUND: This study aimed to describe patterns of long-term antithrombotic use in acute ischemic stroke (AIS) patients with non-valvular atrial fibrillation (NVAF) in Korea and their impacts on clinical events before introduction of non-vitamin K antagonist oral anticoagulants (NOAC) into practice in 2015. METHODS: Patients with NVAF who were admitted due to the AIS and discharged no later than 2008 were enrolled retrospectively. Data were collected at 11 time points during the first 3 years of follow-up. The primary outcome event was a composite of stroke recurrence, major bleeding, and death. Vitamin K antagonist (VKA) users were categorized into a well-controlled INR group and a poorly-controlled INR group (modified TTR ≥47.0% vs <47.0%). RESULTS: Of 1,350 patients enrolled in this study, 95% were on antithrombotic medications at discharge. The rate of VKA usage decreased over time (77% and 40% at discharge and 3 years, respectively). The cumulative event rates of the primary outcome differed by treatment patterns. Among the 10 most frequent treatment types, the highest outcome rate was observed in patients who started with VKA-only therapy but discontinued VKAs during follow-up without restarting (70.2%); this was followed by those starting with antiplatelet-only therapy and stopping it without restart (66.7%). Among VKA users, the 3-year cumulative primary outcome rates were higher in the poorly-controlled INR group than the well-controlled INR group (24.5% vs 15.7%; p = 0.015). CONCLUSION: Our study revealed that, in pre-NOAC era, there was a wide spectrum of long-term antithrombotic use. The incidence of the composite outcome also varied by patterns of antithrombotic use.