Detection of microemboli in patients with acute ischaemic stroke and atrial fibrillation suggests poor functional outcome

Introduction: We investigated the burden of microembolic signals (MES) in patients with acute ischaemic stroke (AIS) and atrial fibrillation (AF), assessing their impact on functional outcomes. Patients and methods: This multicentre international prospective cohort study involved patients with AIS and either a known or newly diagnosed anticoagulant-naïve AF. All centres utilised the same transcranial Doppler machine for 1-h monitoring with bilateral 2 MHz probes within 24 h of symptom onset. Recordings underwent MES analysis by a blinded central reader. The primary objectives were to ascertain the MES proportion and its association with functional outcomes assessed by the modified Rankin scale (mRS) score at 90 days. Results: Between September 2019 and May 2021, we enrolled 61 patients, with a median age of 78 years (interquartile range 73–83) and a median stroke severity score of 11 (interquartile range 4–18). MES were observed in 14 patients (23%), predominantly unilateral (12/14, 86%), with a median rate of 6 counts/hour (interquartile range 4–18). MES occurrence was higher post-thrombectomy and among those with elevated brain natriuretic peptide levels (p < 0.05). A worse mRS score of 3–6 was more frequent in patients with MES, occurring in 11/14 (79%), compared to those without MES, 20/47 (43%), with an adjusted odds ratio of 5.04 (95% CI, 1.15–39.4), p = 0.04. Conclusions: Nearly a quarter of patients with AIS and AF exhibited silent microembolization after the index event. Detecting MES within 24 h post-stroke (using transcranial Doppler) could signify a marker of poor functional outcomes. Subsequent trials will assess if very early antithrombotic treatment might enhance outcomes in this highly selective group of cardioembolic stroke patients. (Clinicaltrials.gov ID: NCT06018090).