AIMS: The clinical correlates and outcomes of asymptomatic atrial fibrillation (AF) in hospitalized patients are largely unknown. We aimed to investigate the clinical correlates and in-hospital outcomes of asymptomatic AF in hospitalized Chinese patients. METHODS AND RESULTS: We conducted a cross-sectional registry study of inpatients with AF enrolled in the Improving Care for Cardiovascular Disease in China-Atrial Fibrillation Project between February 2015 and December 2019. We investigated the clinical characteristics of asymptomatic AF and the association between the clinical correlates and the in-hospital outcomes of asymptomatic AF. Asymptomatic and symptomatic AF were defined according to the European Heart Rhythm Association score. Asymptomatic patients were more commonly males (56.3%) and had more comorbidities such as hypertension (57.4%), diabetes mellitus (18.6%), peripheral artery disease (PAD; 2.3%), coronary artery disease (55.5%), previous history of stroke/transient ischaemic attack (TIA; 17.9%), and myocardial infarction (MI; 5.4%); however, they had less prevalent heart failure (9.6%) or left ventricular ejection fractions ≤40% (7.3%). Asymptomatic patients were more often hospitalized with a non-AF diagnosis as the main diagnosis and were more commonly first diagnosed with AF (23.9%) and long-standing persistent/permanent AF (17.0%). The independent determinants of asymptomatic presentation were male sex, long-standing persistent AF/permanent AF, previous history of stroke/TIA, MI, PAD, and previous treatment with anti-platelet drugs. The incidence of in-hospital clinical events such as all-cause death, ischaemic stroke/TIA, and acute coronary syndrome (ACS) was higher in asymptomatic patients than in symptomatic patients, and asymptomatic clinical status was an independent risk factor for in-hospital all-cause death, ischaemic stroke/TIA, and ACS. CONCLUSION: Asymptomatic AF is common among hospitalized patients with AF. Asymptomatic clinical status is associated with male sex, comorbidities, and a higher risk of in-hospital outcomes. The adoption of effective management strategies for patients with AF should not be solely based on clinical symptoms.

Human induced pluripotent stem cell (iPSC) lines are a powerful tool for studying development and disease, but the considerable phenotypic variation between lines makes it challenging to replicate key findings and integrate data across research groups. To address this issue, we sub-cloned candidate human iPSC lines and deeply characterized their genetic properties using whole genome sequencing, their genomic stability upon CRISPR-Cas9-based gene editing, and their phenotypic properties including differentiation to commonly used cell types. These studies identified KOLF2.1J as an all-around well-performing iPSC line. We then shared KOLF2.1J with groups around the world who tested its performance in head-to-head comparisons with their own preferred iPSC lines across a diverse range of differentiation protocols and functional assays. On the strength of these findings, we have made KOLF2.1J and its gene-edited derivative clones readily accessible to promote the standardization required for large-scale collaborative science in the stem cell field.