Combination of Hypothermia and Thrombectomy in Acute Stroke

Despite the well-established benefit of endovascular treatment (EVT) for acute ischemic stroke due to large vessel occlusion (LVO), more than half of patients treated with EVT remain functionally dependent despite high reperfusion rates. Thus, new strategies such as additional neuroprotection using hypothermia need to be explored, first to bridge time to reperfusion and second, to attenuate reperfusion injury.

Although therapeutic hypothermia has consistently demonstrated robust neuroprotection in animal ischemic-reperfusion models, randomized trials in acute stroke patients have failed to demonstrate the efficacy of induced hypothermia. The reasons for this treatment failure are diverse and include treatment delay, the unfeasibility of inducing and maintaining hypothermia due to intolerance and shivering in awake patients, the missing recanalization in a large proportion of patients, the heterogeneity of patients included, and too deep (32-34°C) hypothermia associated with an increase in side effects.

In the pilot study COTTIS-1, we could demonstrate the feasibility and safety of immediately induced intraischemic hypothermia to 35°C with non-invasive transnasal cooling by RhinoChill® (BrainCool) followed by surface cooling for 6h after recanalization in sedated and intubated patients with LVO undergoing EVT. By combining this cooling technique with thrombectomy we have tried to address the above mentioned reasons for hypothermia failure. In COTTIS-1, the target temperature of 35°C was reached within 30 min, corresponding to a cooling rate of 2.6°C/h. All patients reached the target temperature, and 86% of the patients had reached ≤35°C at recanalization by thrombectomy. 68% of patients had a good outcome (independency) after 3 months. There were only asymptomatic side effects during hypothermia.

As a consequence, the present COTTIS-2 study is planned to evaluate the efficiency of this cooling protocol in a multicentric, randomized, controlled, end-point-blinded study in Germany.

Inclusion criteria

• Pre-stroke modified Rankin Scale (mRS) 0-2 [7-point scale rating from 0 (no symptoms) to 6 (dead)]
• Acute ischemic stroke with NIHSS >5
• Intracranial occlusion of the M1 or M2 segment of the middle cerebral artery (MCA) or internal carotid artery (ICA) or tandem occlusion on CT-angiography or MR-angiography with indication for endovascular treatment:
• Time window 0-24h:

• Last seen normal to groin puncture < 6h: native CT or MRI-DWI with ASPECTS >5
• Last seen normal to groin puncture 6-24h or unknown time window: significant mismatch imaging according to the eligibility criteria of the DEFUSE-3 trial

• Infarct core <70ml (DWI oder CBF<30%)
• Penumbra > 15ml (Tmax >6sec)
• Ratio penumbra/core >1.8
• with or without iv thrombolysis with rtPA

Exclusion criteria

• Patients with an intranasal obstruction that prevents complete insertion of the nasal cannula should not be treated with the RhinoChill system.
• Known severe hemorrhagic diathesis (International Normalized Ratio (INR) >3.0, partial thromboplastin time (PTT) > 70s, platelet count < 50.000/μl)
• Brain trauma or neurovascular surgery/intervention <3 months
• Severe infection
• Pregnant women or women of childbearing potential (women of childbearing potential with negative pregnancy test may be included)
• Known cerebral vasculitis
• Proof of bleeding in cerebral CT or MRI (cerebral microbleeds in MRI [hypertensive or in the context of cerebral amyloid angiopathy] is permitted).
• Known life expectancy < 6 months