Cardiac Assessment for Recurrent Stroke Risk Evaluation in Atrial Fibrillation

Background Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting up to 10% of the elderly. Ischemic stroke is the main complication of AF and cardioembolism is one of the leading causes of ischemic stroke, accounting for approximately one third of cases. Oral anticoagulant therapy (OAC) is a cornerstone in stroke prevention in patients with AF. According to randomized controlled trials of direct oral anticoagulants, a residual risk of ischemic stroke of 1-2% per year for so-called "breakthrough stroke" remains, despite adequate intake of OAC. The majority (\>70%) of these breakthrough strokes are cardioembolic in nature and only a minority are related to medication issues (e.g. non-compliance) or other, non-AF related etiologies. Stroke recurrence risk after such a breakthrough stroke markedly increases to 8-9% per year indicating a particularly high-risk situation. Why OAC fails in certain patients, but not in others remains as poorly understood, as does the reason why the subsequent risk of stroke is so high. Current risk stratification tools, such as the widely used CHA2DS2-VA(Sc)-score, fail to predict stroke risk in such a high-risk cohort, as they were intended to guide the initiation of OAC in low to moderate risk patients. In light of new therapeutic strategies currently being investigated, such as percutaneous left atrial appendage occlusion in patients with breakthrough strokes (ELAPSE - NCT05976685) or in AF-patients deemed high-risk (LAAOS IV - NCT05963698), improved risk stratification and characterization of high-risk AF patients is highly warranted. Several clinical factors, such as those reflected in the CHA2DS2-VA(Sc)-score, and especially a high AF-burden are associated with increased risk of cardioembolic stroke. Several cardiac serum biomarkers are thought to be surrogates not only of cardiac function, but also of cardioembolic risk. Reflecting ventricular and atrial wall tension, myocardial injury, oxidative stress and thr