Journal of Thrombosis and Thrombolysis | 2019
High incidence of under-treated atrial fibrillation: perspectives from an Asian Stroke Endovascular Thrombectomy Registry
Abstract
Large vessel occlusions (LVO) are the most devastating form of strokes with significant disability and mortality [1]. Whilst endovascular thrombectomy (EVT) has revolutionized acute ischaemic stroke (AIS) therapy [2], it requires large up-front costs and resources [3]. In this particular population of patients with LVO amenable to EVT, the mechanism of stroke has traditionally been thought to be cardioembolic in the West, and due to intracranial atherosclerotic disease in Asia [4]. However, several recent studies have instead found that the incidence of atrial fibrillation (AF) is much higher than previously thought in Asian Acute Stroke Registry-based studies. For example, 51.4% of patients in a Japanese LVO EVT registry (RESCUE2 Japan) had AF, whilst the incidence was found to be 49.2% in a similar Korean registry (ASIAN KR) [5, 6]. These appear to be higher than the corresponding AF incidences in Western studies (Fig. 1a) [7–9]. The agents used for stroke prevention in patients with non-valvular AF have undergone a transformation over the last decade with the emergence of various clinical trials supporting the use of direct oral anticoagulants (DOACs) [10]. Although the incidence of stroke has subsequently decreased with the better provision of stroke prevention strategies, suboptimal oral anticoagulant (OAC) use remains widespread in this region. Compared with Europe (90.1%) and North America (78.3%), the reported use of OAC in Asia was significantly lower (55.2%) and well below the global uptake rate (79.9%) [11]. Multiple factors, including a fear of bleeding complications, lower compliance to daily medication and a lack of stroke education, have all been attributed to the underuse of OAC [12]. Particularly in Singapore, there are significant cultural barriers to anticoagulation, whereby prevalence and patients’ reliance on traditional medicines are high. Despite subsidies being available for certain DOACs in eligible patients, the up-front cost of DOACs remains high and may preclude some from choosing this form of anticoagulation [13]. The poor uptake of OAC could perhaps account for the higher prevalence of AF seen in LVO stroke registries in Asia; which whilst its true population prevalence may be low, is emerging as a key risk factor of stroke. We reviewed registry data collected from our 5-year Hyper-Acute Stroke Thrombolysis and Endovascular Thrombectomy (HASTEN) service, which covers the western region of Singapore. We included all consecutive patients who had LVO and underwent EVT to determine the incidence of AF and rate of anticoagulation (Fig. 1b). A total of 306 patients were included, and the median National Institutes of Health Stroke Scale (NIHSS) score on arrival was 20 (IQR = 14–24). 48.0% (N = 147/306) of these patients had AF, of which the vast majority were non-valvular AF (95.9%, N = 141/147). Amongst the patients with previously diagnosed AF prior to stroke onset, anticoagulation was indicated in 82.0% (N = 73/89) [CHA2DS2-VASc score ≥ 2 (male) or ≥ 3 (female)]. However, only 35.6% (N = 26/73) of these patients were actually on anticoagulation. Of which, 61.5% (N = 16/26) were on warfarin, 34.6% (N = 9/26) were on rivaroxaban, and 3.8% (N = 1/26) were on apixaban at the point of stroke presentation. All patients on DOACs were appropriately dosed. The vast majority of patients on warfarin (87.5%, N = 14/16) had subtherapeutic International Normalized Ratios (INR) of less than 2.0. Amongst the stroke * Leonard Leong-Litt Yeo [email protected]