Should Patients With Ischemic Stroke or Transient Ischemic Attack With Atrial Fibrillation and Microbleeds Be Anticoagulated?
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The risk of atrial fibrillation-associated ischemic stroke can be significantly mitigated by anticoagulant therapy with a proven 67% relative risk reduction in ischemic stroke compared with no antithrombotic use.1 Despite this significant therapeutic effect, there still exists substantial underuse of anticoagulants.2 This underuse is driven by exaggerated concerns for anticoagulant-related bleeding complications and in particular, hemorrhagic stroke.3 This concern is further amplified in patients with cerebral microbleeds (CMBs) on MRI (MRI). Whether patients with atrial fibrillation and CMBs on MRI can be safely anticoagulated is a current topic of debate that was recently highlighted by a “Controversies in Stroke” and an area of uncertainty in a recent statement by the American Heart Association/American Stroke Association.4,5
A meta-analysis examining the risk of CMBs for future ischemic and hemorrhagic strokes after an ischemic stroke or transient ischemic attack (TIA) pooled data of 5068 patients across 15 observational studies and revealed that the presence of CMBs was associated with greater relative risk of both ischemic and hemorrhagic strokes during a median follow-up of 18 months.6 However, the relative and absolute risks of hemorrhagic stroke increased more steeply with greater CMB counts than the risks of ischemic stroke, magnifying once again questions surrounding optimal antithrombotic therapy in patients with ischemic stroke/TIA with CMBs, and particularly in patients with greater CMB counts (≥5 CMBs), multiple strictly lobar CMBs suggestive of cerebral amyloid angiopathy or mixed CMB topography presumably marking advanced cerebral small vessel disease.7
In this opinion piece, we apply the risk estimates from this pooled meta-analysis to data reported in recent large, international atrial fibrillation (AF) randomized trials, with the aim of calculating crude estimates on the rates of ischemic and hemorrhagic strokes, as well as margins of benefit, in trial participants stratified by hypothetical CMB …