Relationship between left atrial volume and ischemic stroke subtype

OBJECTIVE: Atrial cardiopathy without atrial fibrillation (AF) may be a potential cardiac source of embolic strokes of undetermined source (ESUS). Atrial volume is a feature of atrial cardiopathy, but the relationship between atrial volume and ESUS remains unclear. METHODS: We compared left atrial volume among ischemic stroke subtypes in the Cornell Acute Stroke Academic Registry (CAESAR), which includes all patients with acute ischemic stroke at our hospital since 2011. Stroke subtype was determined by neurologists per the TOAST classification and consensus ESUS definition. Left atrial volume index (LAVI) was obtained directly from our echocardiography image system (Xcelera, Philips Healthcare). We used t‐tests and analysis of variance for unadjusted comparisons and targeted minimum loss‐based estimation for comparisons adjusted for demographics and comorbidities. RESULTS: Among 2116 patients in CAESAR from 2011 to 2016, 1293 had LAVI measurements. LAVI varied across subtypes (P < 0.001) from 48.8 (±30.0) mL/m(2) in cardioembolic strokes to 30.3 (±10.5) mL/m(2) in small‐vessel strokes. LAVI was larger in ESUS (33.3 ± 13.6 mL/m(2)) than in small‐ or large‐vessel stroke (30.9 ± 10.7 mL/m(2)) (P = 0.01). The association between LAVI and ESUS persisted after the adjustment for demographics and comorbidities: a 10 mL/m(2) increase in LAVI was associated with a 4.4% increase in ESUS probability (95% CI, 2.3%–6.4%). Results were similar after excluding patients with AF during post‐discharge heart‐rhythm monitoring. INTERPRETATION: We found larger left atria among patients with ESUS versus non‐cardioembolic stroke. There was significant overlap in left atrial size between ESUS and non‐cardioembolic stroke, highlighting that many ESUS cases are not cardioembolic.