Different Clinical Phenotypes of Embolic Stroke of Undetermined Source: A Subgroup Analysis of 86 Patients

Embolic strokes of undetermined source (ESUS) represent a rather recent diagnostic entity under clinical research for relapse prevention in cryptogenic stroke patients. Despite strict diagnostic criteria, ESUS definition ignores major clinical and radiological aspects, so including heterogeneous cases and probably influencing trial results. This study researches clinically relevant phenotypes among ESUS patients.

We evaluated ESUS patients admitted at Trento Stroke Unit over a 4-year period. Vascular risk factors (RFs), neurological deficit severity, presence of potential embolic sources, and ASCOD phenotype were recorded. Ischemic lesions were categorized considering their extension in 4 groups. Subgroup comparisons by predefined differences in age, amount of RFs, history of previous stroke, deficit severity, and stroke lesion extension were done.

ESUS cases were 86. Patients younger than 50 years old (n = 17) had a lower prevalence of RFs, left atrial enlargement, left ventricle diastolic dysfunction, a higher proportion of ASCOD score A0 (P < .05). Patients without RFs (n = 18) differed from those with greater than or equal to 3 RFs (n = 23) for a younger age and a lower prevalence of potential causes of embolism (P < .05). Patients without a previous stroke (n = 70) were younger, had a lower prevalence of RFs, left ventricle diastolic dysfunction, a higher prevalence of ASCOD score A0 (P < .05). No differences were observed comparing minor and major clinical and radiological strokes.

ESUS patients can be distinguished in 2 opposite phenotypes defined by a lower and a higher load of atherosclerotic pathology. They may suggest possible underlying pathogenic mechanisms and support interpretation of ongoing trials results.