Highlights
- Cerebral small vessel disease (SVD) burden independently predicts functional decline in patients receiving oral antithrombotic therapy for cerebrovascular or cardiovascular diseases.
- Higher SVD scores (≥3) are associated with significantly increased odds of worsening disability as measured by the modified Rankin Scale (mRS) over 24 months.
- Functional decline attributed to SVD is predominantly a direct effect, not fully mediated by major bleeding or ischemic events during follow-up.
- Early neurological deterioration in lacunar stroke and pre-existing leukoaraiosis are additional clinical facets of SVD, influencing outcomes and therapeutic considerations.
Background
Cerebral small vessel disease (SVD) encompasses a range of pathological processes affecting the brain’s small arteries, arterioles, venules, and capillaries. It manifests radiologically through features such as white matter hyperintensities, lacunes, microbleeds, and enlarged perivascular spaces. SVD is prevalent among elderly patients and those with vascular risk factors, contributing substantially to stroke, cognitive impairment, and functional disability. Despite its recognized role in stroke pathophysiology, the extent to which SVD burden independently drives functional decline, particularly among patients receiving antithrombotic therapy, has remained inadequately characterized. This gap is critical given the balancing act between thrombotic and bleeding risks in such patients and the lack of specific treatments targeting SVD itself.
Key Content
Bleeding With Antithrombotic Therapy 2 (BAT2) Study: Design and Primary Findings
The BAT2 study was an investigator-initiated, prospective, multicenter observational cohort enrolling 5378 patients across 52 Japanese hospitals from 2016 to 2019. These patients were on oral antithrombotic medications for cerebrovascular or cardiovascular conditions and were followed longitudinally for 24 months. The baseline cerebral SVD burden was assessed using a validated SVD scoring system ranging from 0 to 4, based on prespecified MRI criteria including the presence of lacunes, microbleeds, WMH severity, and enlarged perivascular spaces.
The primary functional outcome was an increase in modified Rankin Scale (mRS) score of at least 1 point (ΔmRS ≥1), indicating functional decline. Logistic regression adjusted for confounders (age, sex, premorbid disability, vascular risk factors, type of antithrombotic therapy, MRI field strength, and clinical events during follow-up) demonstrated that patients with higher SVD scores (3 or 4) had significantly increased odds for functional decline (adjusted odds ratios around 1.6) compared to those with no SVD burden. The gradient in risk was dose-dependent, with functional decline rates rising from 13.2% at SVD score 0 to ~28% at scores 3 and 4.
Importantly, causal mediation analyses using four-way decomposition revealed that approximately 73% of the total effect of high SVD burden on functional decline was due to a direct pathway, not mediated by major bleeding or ischemic events during follow-up. This finding underscores that SVD may contribute to disability via mechanisms beyond overt stroke or hemorrhage.
Corroborative Evidence: Early Neurological Deterioration in Lacunar Stroke
Lacunar infarction, a subtype of SVD-related stroke, frequently exhibits early neurological deterioration (END), which negatively impacts recovery. A single-center retrospective study (2013–2023) involving 269 lacunar stroke patients found 11.9% experienced END within 5 days post-onset. Predictive factors included lesion location in internal capsule/lenticular nucleus and sensorimotor lacunar syndrome. Treatment regimens predominantly involved dual antiplatelet therapy and targeted hemodynamic optimization, which showed favorable functional outcomes, with 83.4% achieving good recovery (mRS ≤2) at 90 days.
This evidence highlights the clinical significance of SVD-related pathophysiology in influencing neurological stability in the acute phase and supports vigilant monitoring and tailored therapeutic strategies in this population.
Pre-Existing Leukoaraiosis and Its Functional Impact in Acute Ischemic Stroke
The MRI feature of leukoaraiosis (LA), indicative of chronic white matter ischemic injury and a hallmark of SVD, has been linked to worse post-stroke outcomes. A cohort study of 460 acute ischemic stroke patients revealed that those presenting with LA were older, had a higher prevalence of vascular risk factors (diabetes, hypertension, prior stroke/TIA), and increased cerebral microbleeds than those without LA. Despite prior antiplatelet use, the LA group demonstrated significantly poorer functional outcomes, underscoring the challenges in secondary stroke prevention in the presence of SVD.
These findings emphasize the complex interplay between SVD-related chronic brain injury and response to standard stroke therapies.
Mechanistic Pathways Linking SVD to Functional Decline
The direct effect of SVD on functional deterioration may be mediated by chronic ischemia leading to progressive white matter damage, cortical-subcortical disconnection, small vessel fragility causing repeated microbleeds, blood-brain barrier dysfunction, and neuroinflammation. Such pathologies contribute cumulatively to motor, cognitive, and neuropsychiatric impairments independent of acute symptomatic events.
In patients on antithrombotic therapy, the balance between preventing ischemic events and risking bleeding complications complicates management. The BAT2 study’s finding that SVD-associated functional decline is largely independent of bleeding or ischemia suggests a need to address the underlying SVD pathology directly.
Expert Commentary
The BAT2 investigation offers compelling evidence that SVD burden is a significant and independent predictor of functional decline in patients treated with antithrombotic agents. This signifies a paradigm shift from conventional focus solely on stroke recurrence or hemorrhagic complications towards recognizing and managing SVD as a critical determinant of long-term disability.
Current clinical guidelines for stroke and vascular disease management underscore the importance of vascular risk factor control but offer limited direction on SVD-specific interventions. The lack of approved treatments targeting the pathophysiology of SVD—such as microvascular remodeling, endothelial dysfunction, and chronic small vessel ischemia—represents an unmet clinical need. Moreover, imaging biomarkers like SVD scoring and leukoaraiosis quantification should be integrated into routine risk stratification to personalize therapy.
Additionally, the evidence from END in lacunar stroke and LA-related poor outcomes calls for more research into novel diagnostic modalities, including advanced cerebral perfusion imaging and fluid biomarkers, to enable early identification and individualized therapeutic precision.
Key limitations of current research include observational design constraints and ethnic homogeneity mainly in Japanese cohorts, which may limit generalizability. Future multinational studies and randomized clinical trials are required to validate these findings and test interventions targeting SVD progression.
Conclusion
Cerebral small vessel disease contributes significantly to functional decline beyond the influence of overt ischemic or hemorrhagic events in patients receiving antithrombotic therapy. The BAT2 study establishes a strong, dose-dependent association between MRI-quantified SVD burden and worsening disability over two years. Alongside corroboratory studies on lacunar stroke deterioration and leukoaraiosis-related outcomes, these data highlight the pressing need to incorporate SVD evaluation into clinical risk assessments and develop targeted management strategies. Bridging this knowledge gap will improve prognostication and may pave the way for novel therapeutics that directly address SVD pathophysiology.
References
- Arakaki Y, Miwa K, Koga M, et al; BAT2 Investigators. Impact of Cerebral Small Vessel Disease on Functional Decline: Bleeding With Antithrombotic Therapy 2 Study. Stroke. 2026;57(7):2065-2075. doi:10.1161/STROKEAHA.125.054738. PMID:42220244
- Garcia-Berrocoso T, Giralt D, Bustamante A, et al. Early neurological deterioration in lacunar stroke: Predictive factors and treatment outcomes in a retrospective cohort. Med Clin (Barc). 2026;166(1):107228. doi:10.1016/j.medcli.2025.107228. PMID:41505971
- ElWahab SA, Shaaban YM, ElSabaa NM, et al. Clinical Characteristics and Outcome of Patients with Pre-Existing Leukoaraiosis after Acute Ischemic Stroke. J Stroke Cerebrovasc Dis. 2021 Sep;30(9):105956. doi:10.1016/j.jstrokecerebrovasdis.2021.105956. PMID:34217070
