Embolic Stroke, Atrial Fibrillation, and Microbleeds: Is there a role for anticoagulation?

José G. Merino, MD

Anticoagulation with vitamin K antagonists or one of the new oral anticoagulants (NOACs) is indicated to prevent recurrent stroke for most stroke patients with atrial fibrillation (AF). In these patients the risk of stroke is very high, around 7% to 10% per year, but Coumadin and other anticoagulants can decrease the risk substantially. The most feared risk of anticoagulation -intracerebral hemorrhage (ICH)- is relatively low and the benefits of treatment outweigh the risks.
But does the presence of certain comorbidities change the risk-benefit equation and make anticoagulation too risky for some patients? Patients who have had a lobar ICH, for example, may have an increased risk for recurrent ICH and thus may not be candidates for anticoagulation. Are patients with cerebral microbleeds (CMBs) also ineligible for anticoagulation?

In Stroke, a Controversies article addresses the hypothetical case of a 73-year old man with stroke, AF and 8 cortical CMBs. Hans-Cristoph Diener argues that anticoagulation, perhaps with a NOAC, is indicated because of the very high risk of recurrent stroke in patients with AF and the uncertainty about the risk of ICH in patients with CMBs. Steven Greenberg disagrees and argues that the risk of anticoagulation may be greater than the potential benefit because patients with cortical CMBs may have cerebral amyloid angiopathy (CAA), a condition that leads to ICH, and the fatality rate for anticoagulated patients with ICH is very high. Until there is a better understanding on the relationship between CMBs, anticoagulation, ICH, recurrent stroke and clinical outcome, clinicians must be mindful that anticoagulation may harm their patients with multiple cortical CMBs, particularly when CAA is suspected.

Both authors, along with Magdy Selim and Carlos Molina, editors of the Controversy Section, agree that the decision about anticoagulation in patients with multiple cortical CBMs is challenging and urge clinicians to engage patients in the decision about anticoagulation in this setting by acknowledging the gaps in our understanding of the relationship of AF, CAA, recurrent stroke, ICH and the use of anticoagulants; informing patients (and their families) about alternative strategies and possible outcomes; and eliciting their preferences (how do they weigh the reduced risk of recurrent stroke with increased risk of ICH, for example.) This controversy highlights the value of shared decision making in the face of clinical uncertainty.