RESUMEN
BACKGROUND: Whether presenting an episode of amaurosis fugax (AFx) increases the risk of ischemic stroke is controversial and there is a lack of consensus in the following management. We aimed to describe the clinical characteristics and prognosis of patients with AFx due to suspected transient retinal ischemia. METHODS: Observational, retrospective study of patients admitted in a Comprehensive Stroke Center with diagnosis of AFx due to suspected transient retinal ischemia between 2015 and 2020. Clinical characteristics and diagnostic-therapeutic data were collected, as well as recurrences (new episodes of amaurosis and/or ischemic strokes). Multivariable Cox regression analyses were performed to study factors associated with the risk of recurrence. RESULTS: We included 91 patients with a mean age of 67.9±14.8 years, 43(47.3%) were women. After the diagnostic workup 14(15.4%) AFx were attributed to an atherothrombotic etiology, 4(4.4%) cardioembolic source, 10(11%) other determined cause (TOAST-OC) and 63(69,2%) indeterminate etiology. 71(78%) patients started antiplatelet therapy and 2(2.2%) anticoagulant therapy. After a median follow-up of 3.5 years (IQR 1.8-5.2), at least one recurrence was recorded in eight (8.8%) patients (four new AFx and four cerebral infarctions). TOAST-OC (HR=9.66, 95% CI 2.41-38.70; p=0.001) and prior history of ischemic stroke (HR=4.21. 95% CI 1.01-17.66; p=0.049) were both independently associated with the risk of recurrence. CONCLUSIONS: In two out of three patients, AFx due to transient retinal ischemia was of undetermined cause. The risk of stroke recurrence after a first episode of AFx in our cohort was 8.8%. Patients with TOAST-OC etiology identified were at highest risk of recurrence.
RESUMEN
BACKGROUND: Gut microbiota plays a role in the pathophysiology of ischaemic stroke (IS) through the bidirectional gut-brain axis. Nevertheless, little is known about sex-specific microbiota signatures in IS occurrence. METHODS: A total of 89 IS patients and 12 healthy controls were enrolled. We studied the taxonomic differences of the gut microbiota between men and women with IS by shotgun metagenomic sequencing. To evaluate the causal effect of several bacteria on IS risk, we performed a two-sample Mendelian randomisation (MR) with inverse-variance weighting (IVW) using genome-wide association analysis (GWAS) summary statistics from two cohorts of 5959 subjects with genetic and microbiota data and 1,296,908 subjects with genetic and IS data, respectively. RESULTS: α-Diversity analysis measured using Observed Species (p = 0.017), Chao1 (p = 0.009) and Abundance-based Coverage Estimator (p = 0.012) indexes revealed that IS men have a higher species richness compared with IS women. Moreover, we found sex-differences in IS patients in relation to the phylum Fusobacteria, class Fusobacteriia, order Fusobacteriales and family Fusobacteriaceae (all Bonferroni-corrected p < 0.001). MR confirmed that increased Fusobacteriaceae levels in the gut are causally associated with an increased risk of IS (IVW p = 0.02, ß = 0.32). CONCLUSIONS: Our study is the first to indicate that there are gut microbiome differences between men and women with IS, identifying high levels of Fusobacteriaceae in women as a specific risk factor for IS. Incorporating sex stratification analysis is important in the design, analysis and interpretation of studies on stroke and the gut microbiota.
