Efficacy and Safety of Intravenous Thrombolysis in Branch Atheromatous Disease

Rationale and Relevance: Branch Atheromatous Disease (BAD) describes an atherosclerotic occlusion of one of the deep penetrating cerebral arteries, including the lenticulostriate artery (LSA), paramedian pontine artery (PPA), and anterior choroidal artery (ACHA). BAD is frequently associated with early neurological deterioration (END), particularly progressive motor deficits that contribute to increased disability. Despite its clinical relevance, BAD remains underrepresented in major radiomorphological classification systems such as TOAST, which has led to limited evidence and unclear treatment strategies. Previous studies suggest that the efficacy of intravenous thrombolysis (IVT) may be reduced in BAD compared to other stroke etiologies. Objectives: The primary objective of this study is to evaluate the efficacy and safety of IVT compared with single antiplatelet therapy (SAPT) and dual antiplatelet therapy (DAPT) in patients with BAD-related stroke. A secondary objective is to examine the impact of acute-phase blood pressure fluctuations on END and functional neurological outcomes. Design and Methods: This international multicenter study will be conducted retrospectively according to the STROBE guidelines. Eligible patients include those with BAD-related stroke treated at one of the participating centers between 2010 and 2025. Inclusion criteria comprise characteristic diffusion-weighted MRI patterns in predefined vascular territories (LSA, PPA, ACHA) and a symptom onset ≤24 hours before admission. Patients with typical lacunar infarcts or with other identified stroke etiologies will be excluded. Endpoints: Primary endpoints include functional outcome at three months, defined as a favorable outcome with a modified Rankin Scale score of 0-1; occurrence of END, defined as a ≥4-point worsening on the NIHSS within 24-48 hours; and symptomatic intracerebral hemorrhage. Collected data include clinical, imaging, and therapeutic variables, as well as blood pressure trajectories and pre-stroke treatments (as detailed in the study protocol). Statistical Analysis: Analyses will be performed using SPSS and R. Descriptive statistics, univariate analyses, and multivariable models (IPTW and Poisson regression) will be applied. Results will be reported as adjusted relative risks with 95% confidence intervals. Significance: This study will provide the first comprehensive evaluation of IVT versus SAPT/DAPT in BAD-related stroke, and will investigate the clinical impact of blood pressure changes in this specific stroke subtype. The findings aim to support evidence-based treatment recommendations for a currently underrecognized and poorly understood stroke etiology.