Seek and Ye Shall Find Fibrillations

Atrial fibrillation detected with outpatient cardiac rhythm monitoring in patients with ischemic stroke or TIA of undetermined cause

OBJECTIVES

Guidelines advise cardiac rhythm monitoring for 3 up to 30 days for detecting atrial fibrillation (AF) in patients with ischemic stroke of undetermined cause. However, the optimal monitoring duration is unknown. We aimed to determine the AF detection rate during 7-day outpatient cardiac rhythm monitoring in this patient group.

METHODS

Participants from a large tertiary hospital in a prospective observational study (ATTEST) underwent outpatient cardiac rhythm monitoring after a negative standard diagnostic evaluation (i.e., 12-lead electrocardiogram and in-hospital telemetry). Primary outcome was the rate of newly detected AF.

RESULTS

We examined 373 patients [age: 67.8±11.6 years; women: 166(44.5%); stroke: 278(74.5%)]. Median monitoring duration was 7 days (Inter Quartile Range (IQR) 7-7), performed after median of 36 days (IQR 27-47). AF was newly detected in 17(4.6%) patients, 5.4% of patients with ischemic stroke and 2.1% of patients with TIA. 53% of AF was detected on day-1, after day-3 73% of new AF was found. First AF episodes were detected up to day-7. Diabetes and increasing age were independent predictors of new AF.

CONCLUSION

After ischemic stroke or TIA of undetermined cause, 7-day outpatient cardiac rhythm monitoring detected new AF in 4.6%. Patients with AF had significantly more cardiovascular risk factors. Although about 50% of first AF episodes occurred during the first day of monitoring, new AF was detected up to day-7, implying that the recommended minimum of 3 days cardiac rhythm monitoring after ischemic stroke of undetermined cause is insufficient. Subsequent long-term rhythm monitoring should be considered in selected patients.

Direct Oral Anticoagulant Failures in Atrial Fibrillation With Stroke: Retrospective Admission Analysis and Novel Classification System

Introduction

Breakthrough acute ischemic stroke (AIS) in patients with known, nonvalvular Atrial Fibrillation (AF), on Direct Oral Anticoagulants (DOAC), is an ongoing clinical conundrum. Switching anticoagulants was shown to be ineffective in preventing recurrent AIS. Systematic, patient-level chart review of so-called "DOAC failures" may offer insight into this phenomenon.

Methods

We conducted an IRB-approved, 6-year, retrospective study of AIS admissions, already prescribed DOAC for known AF. We sought plausible, alternative reasons for the AIS using a novel classification schema, CLAMP: C for Compliance concerns, L for Lacunes (small-vessel disease), A for Arteriopathy (atherosclerosis, web, or vasculitis), M for Malignancy, and P for Patent Foramen Ovale (PFO). These categories were labeled as DOAC "Pseudo-failures." Conversely, absence of CLAMP variables were labeled as DOAC "Crypto-failures" conceivably from AF itself ("atriopathy") or pharmacokinetic/pharmacogenomic dysfunction (ie, altered DOAC absorption, clearance, metabolism, or genetic polymorphisms). Forward logistic regression analysis was performed on prespecified DOAC subgroups.

Results

Of 4890 AIS admissions, 606 had AF, and 87 were previously prescribed DOAC (14.4% overall DOAC failure rate, 2.4% annualized over 6 years). Pseudo-failures comprised 77%: Compliance concerns (48.9%), Lacunes (5.7%), Arteriopathy (17.0%), Malignancy (26.1%), and PFO (2.3%). Crypto-failures comprised 23%, had lower CHADSVASc scores (AOR = .65, P = .013), and occurred more with rivaroxaban (41%) than apixaban (16%) or dabigatran (5.6%).

Conclusion

In AIS patients with known AF, DOAC Pseudo-failures, with identified alternate etiologies, are 3 times more likely than DOAC Crypto-failures. The CLAMP schema represents a novel approach to diagnostic classification and therapeutic adjustments in patients already prescribed DOAC for AF.

Web Browsing: High-Speed Diagnosis and Treatment of Carotid Artery Web

Background: Although carotid artery web (CaW) was initially described in 1973 as a potential etiology of ischemic stroke, it still remains underrecognized. Because CaW is a membrane affixed perpendicularly from the carotid wall that projects out into the lumen above the bifurcation, it typically is not stenotic, and hence, utilizing only 1 vessel imaging modality during conventional stroke workup may instead lead to a diagnosis of ESUS: embolic stroke of undetermined source. The term ESUS was created in 2014 by researchers to define a subset of cryptogenic, nonlacunar (embolic-appearing) strokes without clear cardiac or vascular cause. Purpose: In this review, we describe how, after multiple evaluations of vessels, CaW was diagnosed in relatively young patients (age 39-47 years old, without significant vascular risk factors) in whom otherwise were considered embolic stroke of undetermined source. This observation dovetails with the accompanying  Neurohospitalist article entitled, “Delayed Thrombus Formation on Carotid Web and Its Medical and Endovascular Management for Secondary Stroke Prevention.” Research Design: Not applicable. Case review. Results/Conclusion: This report demonstrates the futility of antiplatelet therapy for a young patient with CaW-related stroke. Based on these collective experiences and review of the literature, we postulate that: (1) multiple vascular imaging modalities during stroke workup may result in a CaW diagnosis instead of ESUS; (2) young stroke patients without traditional vascular risk factors are candidates for this “web browsing” of extended imaging of vessels; and (3) carotid artery stenting (CAS) or carotid endarterectomy (CEA) may be preferred as first-line over medical therapy alone (ie, antiplatelet or anticoagulation) because CEA/CAS addresses the stroke etiology, CaW, definitively.

Protocol for AREST: Apixaban for Early Prevention of Recurrent Embolic Stroke and Hemorrhagic Transformation-A Randomized Controlled Trial of Early Anticoagulation After Acute Ischemic Stroke in Atrial Fibrillation

Background: Optimal timing to initiate anticoagulation after acute ischemic stroke (AIS) from atrial fibrillation (AF) is currently unknown. Compared to other stroke etiologies, AF typically provokes larger infarct volumes and greater concern of hemorrhagic transformation, so seminal randomized trials waited weeks to months to begin anticoagulation after initial stroke. Subsequent data are limited and non-randomized. Guidelines suggest anticoagulation initiation windows between 3 and 14 days post-stroke, with Class IIa recommendations, and level of evidence B in the USA and C in Europe. Aims: This open-label, parallel-group, multi-center, randomized controlled trial AREST (Apixaban for Early Prevention of Recurrent Embolic Stroke and Hemorrhagic Transformation) is designed to evaluate the safety and efficacy of early anticoagulation, based on stroke size, secondary prevention of ischemic stroke, and risks of subsequent hemorrhagic transformation. Methods: Subjects are randomly assigned in a 1:1 ratio to receive early apixaban at day 0-3 for transient ischemic attack (TIA), 3-5 for small-sized AIS (<1.5 cm), and 7-9 for medium-sized AIS (1.5 cm or greater but less than a full cortical territory), or warfarin at 1 week post-TIA or 2 weeks post-stroke. Large AISs are excluded. Study Outcomes: Primary: recurrent ischemic stroke, TIA, and fatal stroke; secondary: intracranial hemorrhage (ICH); hemorrhagic transformation (HT) of ischemic stroke; cerebral microbleeds (CMBs); neurologic disability [e.g., modified Rankin Scores (mRS), National Institutes of Health Stroke Scale (NIHSS), Stroke Specific Quality of Life scale (SS-QOL)]; and cardiac biomarkers [e.g., AF burden, transthoracic echo (TTE)/transesophageal echo (TEE) abnormalities]. Sample Size Estimates: Enrollment goal was 120 for 80% power (two-sided type I error rate of 0.05) to detect an absolute risk reduction of 16.5% postulated to occur with apixaban in the primary composite outcome of fatal stroke/recurrent ischemic stroke/TIA within 180 days. Enrollment was suspended at 91 subjects in 2019 after a focused guideline update recommended direct oral anticoagulants (DOACs) over warfarin in AF, excepting valvular disease (Class I, level of evidence A). Discussion: AREST will offer randomized controlled trial data about timeliness and safety of anticoagulation in AIS patients with AF. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02283294.