Mixed Results for Targeted Focal Cooling During Stroke Thrombectomy

Why It Matters

If intra‑arterial cooling can reliably improve functional recovery, it could become a low‑cost adjunct to thrombectomy, reshaping acute stroke care; the divergent findings underscore the need for broader validation before practice changes.

Key Takeaways

• CHILL‑ART showed 54.7% functional independence vs 39.8% control
• FOCUS found no significant difference in mRS distribution at 90 days
• Intra‑arterial cooling reduced infarct volume by 8.77 mL in CHILL‑ART
• Both trials used 4 °C saline infusion via microcatheter
• Safety profiles were comparable; pneumonia rates remained ~40%

Pulse Analysis

Acute ischemic stroke remains a leading cause of disability, and mechanical thrombectomy has become the cornerstone of reperfusion therapy. Yet, only about half of patients achieve functional independence, prompting investigators to explore neuroprotective adjuncts. Systemic hypothermia, while theoretically beneficial, has consistently failed to improve outcomes and raises infection risks. Targeted intra‑arterial cooling offers a way to lower brain temperature locally, preserving the blood‑brain barrier and limiting reperfusion injury without systemic side effects, positioning it as a promising next‑generation strategy.

The CHILL‑ART trial enrolled 262 patients across 26 Chinese centers, delivering 4 °C saline through a microcatheter before and after thrombectomy. The cooling arm achieved a 54.7% rate of modified Rankin Scale 0‑2 at 90 days versus 39.8% in the sham group, yielding a number‑needed‑to‑treat of seven and an 8.77 mL reduction in infarct size. Importantly, adverse events—including symptomatic intracerebral hemorrhage and mortality—were similar between groups, and the intervention required only refrigerated saline and standard thrombectomy equipment, suggesting a cost‑effective implementation pathway worldwide.

Conversely, the FOCUS study, with a comparable patient cohort, reported no statistically significant advantage in functional outcomes, despite using a similar cooling regimen. Differences in post‑procedure cooling timing and the absence of a sham infusion may have diluted the therapeutic signal. Nonetheless, FOCUS noted a lower early intracranial hemorrhage rate with cooling, hinting at a protective effect on the vascular endothelium. These mixed results highlight the necessity for larger, multinational trials to clarify optimal protocols, patient selection, and long‑term benefits. Emerging approaches, such as extracorporeal blood cooling, could further refine regional hypothermia, potentially unlocking a durable neuroprotective adjunct for stroke care.