Cardioembolic stroke versus embolic stroke of undetermined source: early severity and long-term outcomes in a prospective cohort

Abstract Background Embolic stroke of undetermined source (ESUS) constitutes a substantial proportion of ischemic strokes. Its distinction from cardioembolic stroke (CES) may carry prognostic implications. This study aimed to compare early and long-term outcomes between ESUS and CES. Methods We conducted a prospective cohort study of patients with ESUS and CES who underwent standardized diagnostic evaluation and prolonged cardiac monitoring. Stroke severity was assessed with the NIHSS, and functional outcome with the mRS at discharge, 30 days, and 12 months. ESUS patients were additionally evaluated for short-duration atrial fibrillation. Results During a 6-month prospective enrollment period, 771 patients with suspected stroke were screened, of whom 529 had ischemic stroke confirmed by neuroimaging. After applying ESUS criteria, 98 patients were classified as ESUS and 209 as CES (total study cohort, n = 307; 41% women; mean age 72 ± 9 years). Patients with ESUS presented with significantly lower stroke severity and achieved better functional outcomes than those with CES. The mean NIHSS score on admission was 6 (95% CI, 5–7) in the ESUS group and 11 (95% CI, 10–12) in the cardioembolic group ( p < 0.001). At discharge, the mean mRS score was 2.1 (95% CI, 1.8–2.4) for ESUS and 3.8 (95% CI, 3.5–4.1) for CES ( p < 0.001). A favorable outcome (mRS 0–2) was more common in ESUS (68% vs. 34%; p < 0.001). In-hospital mortality occurred in 10.0% of cardioembolic patients and in none of the ESUS patients ( p = 0.02). At 12 months, ESUS patients continued to show more favorable recovery, with higher rates of functional independence (60% vs. 28%; p < 0.001) and lower cumulative mortality (7.1% vs. 21.5%; p < 0.001). Conclusions Compared with CES, ESUS was associated with less severe neurological deficits and more favorable outcomes, both early and at 12 months, including lower mortality and better functional recovery.