Capsular Warning Syndrome: Features, Risk Profile, and Prognosis in a Large Prospective TIA Cohort

Introduction: Features and prognosis of capsular warning syndrome (CWS) have been poorly investigated prospectively. Aims: The study aimed to characterize CWS clinical features, risk profile, short- and long-term prognosis, among a large TIA cohort. Methods: Prospective cohort study of consecutive TIAs was conducted from August 1, 2010, to December 31, 2017. Demographic and clinical characteristics, risk profile, primary (stroke and composite outcome) and secondary (TIA recurrence, cerebral hemorrhage, new onset atrial fibrillation) outcomes were compared between CWS, lacunar (L), and nonlacunar (NL) TIAs. Results: 1,035 patients (33 CWS, 189 L-TIAs, 813 NL-TIAs) were enrolled. Newly diagnosed (ND) hypertension, hypercholesterolemia, cigarette smoking, and leukoaraiosis were independent risk factors of CWS (p < 0.05). CWS showed the highest stroke (30.3% vs. 0.5% and 1.5% for L-TIAs and NL-TIAs, respectively) and composite outcome risk at follow-up (p < 0.001), but better 3-month post-stroke prognosis (mRS 0-2 90.0% vs. 36.8%; p = 0.002). CWS-related stroke mostly occurred <48 h (80.0%) and had a small vessel occlusion etiology (100%), affecting more often the internal capsule (60.0%). Dual antiplatelet therapy (DAPT) versus single antiplatelet therapy was associated with lower 3-month cumulative stroke incidence (12.5% vs. 57.1%; p = 0.010). Intravenous thrombolysis (IVT) showed similar 3-month efficacy and safety in strokes after TIAs groups (median mRS 0, IQR 0-1; p = 0.323). Conclusions: CWS is associated with higher stroke risk and better functional prognosis than L- and NL-TIAs. CWS risk profile is consistent with severe small vessel disease, and ND hypertension could represent a major risk factor. DAPT and IVT seem effective and safe in preventing and treating stroke following CWS.