Post-Thrombectomy Mild Hypercapnia State Prevents Poor Outcome by Reducing Infarct Progression

In endovascular therapy (EVT) for stroke, futile recanalization contributes to poor prognosis. Mild hypercapnia may enhance cerebral blood flow and prevent ischemia, but its impact on prognosis in successfully recanalized EVT patients is unclear.

We retrospectively analyzed 237 patients from the INSPIRE database who underwent successful recanalization at our center (October 2018-March 2022). Patients were grouped by post-EVT PaCO₂ levels: high (40-50 mmHg) and low (<40 mmHg). Significant infarct expansion (SIE) was defined as a decrease in ASPECTS or pc-ASPECTS by ≥2 from initial to 3-5 days post-EVT. Poor outcome was modified Rankin Scale score 3-6 at 90 days.

High PaCO₂ was negatively associated with SIE (OR 0.42, 95% CI 0.22 to 0.84) and poor outcome (OR 0.42, 95% CI 0.20 to 0.87). Mediation analysis showed a significant total effect of high PaCO₂ on poor outcome (coefficient -0.192, 95% CI -0.345 to -0.046), including an indirect effect mediated by SIE (coefficient -0.055, 95% CI -0.10 to -0.006). These associations were consistent in anterior circulation stroke and patients without severe low PaCO₂ (<30 mmHg).

Maintaining mild hypercapnia (PaCO₂ 40-50 mmHg) after EVT may prevent poor outcomes by reducing post-EVT infarct progression.