Mitigation of Stroke Risk in Nonvalvular Atrial Fibrillation Patients With High-Grade Carotid Artery Stenosis

Abstract

Notwithstanding the efficacy of the new oral anticoagulants (NOACs) in mitigating the risk of systemic thromboembolism associated with nonvalvular atrial fibrillation (NVAF), as recently published in the Journal by Khattak et al, 1 Khattak F. Alam MB Paul TK et al. Antithrombotic therapy in nonvalvular atrial fibrillation: Consensus and challenges. Am J Med Sci. 2018; 355: 467-476 Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar clinicians also need to recognize that these agents might not mitigate the risk of stroke attributable either to high-grade carotid artery stenosis or stenotic intracranial vascular disease that might coexist with NVAF. The opportunity to evaluate the magnitude of this problem was squandered when we omitted carotid artery sonography (to identify carotid artery stenosis) from the CHA2DS2-VASc risk stratification scheme. 2 Lip GY Nieuwlaat R Pisters R et al. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach. The Euro Heart Survey on atrial fibrillation. Chest. 2010; 137: 263-272 Google Scholar This omission was compounded by the exclusion of NVAF patients from clinical trials evaluating the efficacy of invasive treatment of high-grade carotid artery stenosis. 3 Brott TG Hobson RW Howard G et al. Stenting versus endarterectomy for treatment of carotid artery stenosis. N Engl J Med. 2010; 363: 11-23 Crossref PubMed Scopus (2299) Google Scholar , 4 Rosenfield K Matsumura JS Chaturvedi S et al. Randomized trial of stent versus surgery for asymptomatic carotid stenosis. N Engl J Med. 2016; 374: 1011-1020 Crossref PubMed Scopus (387) Google Scholar Consequently, we can only rely on small scale studies to gauge the prevalence of high-grade carotid artery stenosis (CAS) in NVAF. One such study comprised of 103 consecutive ischemic stroke patients of mean age 69 with NVAF. High-grade (50% or more) stenosis of the extracranial carotid artery was detected in 25 patients. In 15 of the 25 patients (66.7%) with high-grade stenosis, the lesion was ipsilateral to the ischemic cerebral infarct, signifying a causal relationship with the stroke event. 5 Chang Y-J Ryu S-J Lin S-K Carotid artery stenosis in ischemic stroke patients with nonvalvular atrial fibrillation. Cerebrovas Dis. 2002; 13: 16-20 Crossref PubMed Scopus (56) Google Scholar In another study, a comparison was made between 165 NVAF patients with ischemic stroke (or transient ischemic attack) and high-grade CAS versus 734 counterparts who did not have high-grade CAS. In that study, among 907 NVAF patients presenting with stroke, and in whom carotid artery sonography was performed, the prevalence of high-grade CAS was 18%. At the time of the index stroke, 54.9% of the CAS patients were on anticoagulants versus 44.4% of the non-CAS patients. Among those with CHA2DS2-VASc score of 2 or more, significantly (P = 0.03) more CAS patients were on oral anticoagulants than non-CAS patients. All but 3 of the anticoagulant-treated patients were on warfarin. The median international normalized ratio on admission was similar in the 2 groups. Carotid artery stenting or endarterectomy was performed in 24.8% of the CAS patients. After the index stroke these patients were followed up for a median of 2.5 years in the CAS group and for a median of 3.7 years in the non-CAS group. Stroke recurrence was significantly (P = 0.005) higher in the CAS group than in the non-CAS group. Carotid artery stenosis was an independent (P = 0.001) predictor of stroke recurrence. Compared to non-CAS patients, the stroke recurrence rate was higher both in the conservatively treated and invasively treated CAS group (20.8% versus 12.6%), (P = 0.015, and 25.6% versus 12.6%), (P = 0.019, respectively). 6 Lehtola H Airaksineh KEJ Hartikalnen P et al. Stroke recurrence in patients with atrial fibrillation: concomitant carotid artery stenosis doubles the risk. Euro J Neurol. 2017; 24: 719-725 Crossref PubMed Scopus (34) Google Scholar