Post-Thrombectomy White Matter Infarct Volume a Strong Determinant of Disability After Large-Vessel Occlusion Stroke
Key findings
- This study is the first to quantify region-specific infarct volumes after endovascular thrombectomy (EVT) for anterior circulation large-vessel occlusion stroke
- White matter accounted for 39% of total infarct volume
- Greater post-EVT white matter infarct volume was associated with decreased odds of functional independence at 90 days (OR, 0.89; 95% CI, 0.81–0.96; P=0.005)
- In addition to predicting long-term outcomes, white matter infarct volume may have implications for patient selection for EVT and the development of neuroprotective and neuroreparative agents
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Over the past few years, endovascular thrombectomy (EVT) has transformed the treatment algorithm for the most devastating type of acute ischemic stroke, large vessel occlusion (LVO). However, 90 days later, 54% of treated patients remain functionally disabled or have died, according to a meta-analysis published in The Lancet.
Previous studies in stroke patients have shown that white matter survives longer than gray matter at every degree of hypoperfusion, likely due to different metabolic demands and different chemical cascades triggered by ischemia. Now, Robert W. Regenhardt, MD, PhD, neuroendovascular fellow, and Natalia S. Rost, MD, MPH, of the Department of Neurology at Massachusetts General Hospital, and colleagues have found evidence that post-EVT white matter infarct volume is one of the most important determinants of long-term outcomes. They report their findings in the Journal of Stroke and Cerebrovascular Diseases.
Study Methods
The researchers identified 381 consecutive patients who underwent EVT for anterior LVO at Mass General between January 2011 to September 2019. Post-EVT MRI scans were available for 167 patients and were reviewed by a vascular neurologist blinded to clinical data.
Infarct Volume
After EVT, the median total infarct volume was 45 cc (IQR, 18–122 cc). The median percentages of total infarct were:
- White matter: 39%
- Cortex: 42%
- Basal ganglia: 7%
Functional Independence
43% of the 167 patients were functionally independent at 90 days post-procedure (defined as a score of 0–2 on the modified Rankin scale). The odds of functional independence were independently reduced with greater post-EVT white matter infarct volume (OR, 0.89; 95% CI, 0.81–0.96; P=0.005) in a multivariable model controlling for infarct volumes in other regions, age, stroke severity and successful reperfusion.
Proportions of patients who reached functional independence varied significantly (P<0.0001) depending on quartile of white matter infarct volume:
- First quartile (<6.0 cc): 68%
- Second quartile: 66%
- Third quartile: 32%
- Fourth quartile (>49.4 cc): 8%
Clinical Implications
In addition to predicting long-term outcomes, white matter volume may have implications for patient selection for EVT. For example, patients with minimal white matter infarction, despite borderline total infarct volume, may be more likely to benefit from EVT.
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