Prevalence, Predictors, and Prognostic Implications of Covert Brain Infarctions in First-Ever Acute Ischemic Stroke: A South Indian Study

Background: Covert brain infarctions (CBIs) are imaging-detected ischemic lesions without overt neurological symptoms. Their role in determining short-term outcomes and recurrence risk in acute ischemic stroke (AIS) remains underexplored. Objectives: To evaluate the prevalence, predictors, and impact of CBI on outcomes and recurrence in patients with first-ever AIS. Methods: Single-centre ambispective observational study of patients with first-ever AIS and completed one-year follow-up. Demographics, vascular risk profiles, imaging findings including covert infarct location and phenotype, and outcome metrics (functional outcome and recurrence) were studied. Results: We had 350 subjects in our study cohort. CBI was observed in 132 (37.7%) patients. Most common CBI locations were subcortical supratentorial (50.5%) and cortical supratentorial (27.2%). Frequent phenotypes included combined grey and white matter lesions (40%) and cavitatory lacunes (34.5%). CBI was significantly associated with older age (OR 2.38, p=0.001), vertebrobasilar territory infarcts (OR 2.26, p=0.004), watershed infarcts (OR 2.21, p=0.012), and multiple embolic infarcts (OR 2.91, p=0.001),but not with vascular risk factors or etiological subtypes.Though patients with CBI showed a trend towards increased recurrence risk in the early phase,functional outcomes at one year was favourable. Conclusions: CBIs are prevalent in over one-third of first-ever AIS cases and are linked to specific infarct patterns and advanced age, rather than classic stroke risk factors. Though not associated with long-term disability, their presence may portend early recurrence. Recognition and characterization of CBI should inform post-stroke monitoring strategies and future preventative trials.