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

## TL;DR

Keeping mild hypercapnia after stroke treatment may improve outcomes by slowing brain damage.

## Contribution

This study shows that mild hypercapnia after stroke treatment reduces infarct progression and poor outcomes.

## Key findings

- High PaCO2 levels were linked to reduced infarct expansion and better outcomes.
- Mediation analysis showed that high PaCO2 reduces poor outcomes partly by preventing infarct expansion.
- The effect was consistent in anterior circulation stroke and patients without severe low PaCO2.

## Abstract

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.

Maintaining mild hypercapnia (PaCO2 40–50 mmHg) within the initial 24 h after endovascular therapy may prevent poor outcomes by reducing post‐EVT infarct progression.