Treatment of Large Ischemic Stroke with >1/3 MCA Territory Involvement
For patients presenting within 3 hours of symptom onset with >1/3 MCA territory involvement on CT, IV rtPA should still be administered, as early infarct signs of this extent do not preclude treatment or predict unfavorable response to therapy within this time window. 1
Critical Time-Based Treatment Algorithm
Within 0-3 Hours of Symptom Onset
Administer IV rtPA (0.9 mg/kg) immediately even with extensive early infarct signs involving >1/3 MCA territory, as these patients still benefit from therapy and the presence of these signs does not independently increase risk of adverse outcomes 1
Simultaneously prepare for endovascular thrombectomy while IV rtPA is being administered - do not wait to assess clinical response to thrombolytics before proceeding to mechanical intervention 2, 3
Target door-to-needle time <60 minutes and door-to-groin puncture <110 minutes to maximize functional outcomes 3
Within 3-6 Hours of Symptom Onset
Proceed directly to endovascular thrombectomy with stent retrievers for proximal MCA (M1) or ICA occlusions if NIHSS ≥6, ASPECTS ≥6, and prestroke mRS 0-1 2, 4, 3
IV rtPA is not recommended beyond 3 hours outside of clinical trials, regardless of CT findings 1
Stent retrievers are the preferred device (Class I, Level A evidence), achieving TICI 2b/3 recanalization in 59-87.8% of cases 2, 3
Within 6-24 Hours of Symptom Onset (Extended Window)
Consider endovascular thrombectomy only if perfusion imaging demonstrates salvageable tissue with clinical-imaging mismatch 5, 6
Specific criteria include: initial infarct size <70 mL and ratio of ischemic tissue volume to infarct volume ≥1.8 on perfusion imaging 5
This approach resulted in 45% functional independence versus 17% with medical therapy alone in the DEFUSE 3 trial 5
Critical Caveat for Extensive Hypodensity Within 3 Hours
There is an important exception: If CT reveals extensive (>1/3 MCA territory) and clearly identifiable hypodensity (not just early infarct signs like loss of gray-white differentiation or sulcal effacement) in patients within 3 hours, expert opinion is divided 1. Some experts recommend withholding thrombolytic therapy in these rare cases due to suspected unfavorable risk/benefit ratio, though insufficient data exists for a strong recommendation 1.
The distinction here is crucial:
- Early infarct signs (loss of gray-white differentiation, sulcal effacement, lentiform nucleus obscuration) = proceed with IV rtPA 1
- Frank hypodensity (clearly established infarction) = consider withholding IV rtPA based on expert opinion 1
Hemorrhagic Risk Management
Symptomatic hemorrhage risk increases 8-fold with early edema or mass effect on CT after rtPA administration 1
Maintain blood pressure ≤180/105 mmHg during and for 24 hours after reperfusion therapy 2, 4
Monitor intensively in specialized stroke unit with capabilities for managing post-thrombectomy complications 2
Malignant Edema Considerations
Young patients (<60 years) with large MCA infarctions should be monitored closely for malignant edema 4
Decompressive hemicraniectomy within 48 hours reduces mortality by approximately 50% in young patients with malignant MCA infarction and should be considered early if signs of significant edema or mass effect develop 4
Key Pitfalls to Avoid
Never delay endovascular therapy while waiting for clinical response to IV rtPA - every 30-minute delay decreases chance of good outcome by 8-14% 2, 3
Physician accuracy in detecting >1/3 MCA involvement is only 70-80%, so do not rely solely on this assessment to exclude patients from treatment within 3 hours 1
Do not confuse early infarct signs with established hypodensity - the former does not contraindicate rtPA within 3 hours, while the latter may 1