Phenotypes of atrial fibrillation diagnosed before-versus-after ischaemic stroke and TIA: study protocol for a systematic review and meta-analysis.

Introduction The underlying pathophysiology of atrial fibrillation (AF) detected after stroke (AFDAS) is relatively unknown. Preliminary evidence suggests AFDAS has a lower prevalence of cardiovascular comorbidities and higher incidence of insular cortex involvement than AF known to exist before stroke occurrence (KAF). This favours a neurogenic AF substrate (autonomic dysregulation) in which the presence of underlying heart disease is not necessary for AF to occur. The main objective of this systematic review and meta-analysis is to compare the prevalence of cardiovascular comorbidities and echocardiographic abnormalities in patients with AFDAS, KAF and no AF (NAF). Secondary objectives are to compare the proportion with insular cortex involvement, stroke recurrence and death in the three rhythm groups. Methods and analysis We will perform a systematic review including cross-sectional, case–control, cohort studies and clinical trials involving ≥18 years patients, with ischaemic stroke or transient ischaemic attack published between inception and 31 December 2020 in any language, and reporting the proportion of patients with AFDAS, KAF and NAF. We will search PubMed, EMBASE and Scopus by applying predefined search terms. Two reviewers will independently screen titles and abstracts and retrieve full texts, extract data in a predesigned form, and assess the risk of bias. We will perform a meta-analysis of all included studies and we will report the results of the main outcome as proportions. We will report results of secondary outcomes as risk ORs. We will estimate heterogeneity across studies by using t2, Q and I2 measures. We will use funnel plots, Rosenthal’s Fail-Safe N and Egger’s regression intercept to assess publication bias. Ethics and dissemination This study will be based on published data and does therefore not require ethical clearance. The results will be published in peer-reviewed journals. PROSPERO registration number CRD42020202622.