Collateral status correlates with stroke outcomes mediated by early infarct growth rate in patients with acute large...

Early infarct growth rate (EIGR) and both arterial- and tissue-level collaterals (TLCs) are strongly associated with stroke prognosis, yet the complex interplay among multi-level collateral status, EIGR, and stroke outcomes remains incompletely understood. This study aimed to comprehensively characterize collaterals at the arterial, tissue, and venous outflow (VO) levels, and to delineate the distribution of EIGR among acute stroke patients with varying clinical outcomes.

Patients with acute large vessel occlusion were retrospectively recruited. Pial arterial collaterals (PACs), TLCs and VO were measured by the modified Tan (mTan) scale, hypoperfusion intensity ratio (HIR), and the cortical vein opacification score (COVES), respectively. EIGR was subsequently calculated. The imaging and clinical outcomes were measured by final infarct volume (FIV) and modified Rankin Scales (mRS) at 90 days, respectively. Mediation analysis was performed to quantify the effect of collaterals on outcomes as explained by EIGR.

A total of 166 patients were included, with 61 exhibiting good clinical outcomes and 105 poor outcomes. The median EIGR and FIV were 2.0 mL/h and 14.4 mL in the good clinical outcome group, and 11.3 mL/h and 126.5 mL in the poor outcome group. Patients with unfavorable collaterals developed significantly higher EIGR. The mTan score (r=-0.456, P<0.001), HIR (r=0.314, P<0.001) and COVES score (r=-0.300, P<0.001) demonstrated significant correlations with EIGR. Presentation National Institutes of Health Stroke Scale (NIHSS) score and EIGR were identified to be co-determinants of FIV and mRS. EIGR mediated 28.2%, 27.9% and 32.2% of the effects of PACs, TLCs, VO on FIV and 33.7%, 25.9% and 35.9% on mRS, respectively.

Collaterals and EIGR were integral determinants of stroke prognosis, with EIGR functioning as a key mediator. These findings offer a more nuanced understanding of how different levels of collateral flow influence infarct evolution and stroke outcomes in acute ischemic stroke (AIS).