Acute MCA Occlusion with a Borderline Perfusion Mismatch
A 68-year-old man with hypertension and atrial fibrillation presents 4.5 hours after sudden onset of right hemiparesis and global aphasia. NIHSS is 16. Noncontrast CT shows a hyperdense left M1 sign without hemorrhage and an ASPECTS of 7 (early loss in insula and M2 territory). CT angiography confirms left M1 occlusion with good distal vessel reconstitution. CT perfusion (RAPID-style automated output) reports an ischemic core of 52 mL and a Tmax>6 s volume of 118 mL, giving a mismatch ratio of 2.3. His creatinine is 1.4 mg/dL, he is on apixaban (last dose 14 hours ago), and his blood pressure is 178/96 mmHg. The stroke team is debating intravenous thrombolysis versus mechanical thrombectomy versus both.
1. Interpret the perfusion numbers against commonly used trial enrollment thresholds. Does this patient qualify for mechanical thrombectomy on imaging grounds, and what is the key caveat about the core volume?
Read the worked answer
The mismatch ratio is 118/52 = 2.3, which exceeds the commonly cited ratio threshold of 1.8, and the mismatch volume is 118 − 52 = 66 mL, above the ~15 mL threshold. However, the absolute core of 52 mL is near the upper boundary used in late-window trials (core <70 mL in DAWN, and <70 mL with mismatch criteria in DEFUSE 3). So on pure numbers he is enrollable but sits close to the ceiling - small changes in core segmentation (e.g., including the insular/M2 early ischemic change) could push him out. The caveat: automated core estimates are threshold-dependent and can be inflated by chronic white matter disease or poor bolus; always sanity-check the core map against the noncontrast CT and the clinical deficit rather than treating the RAPID number as ground truth.
2. Given the 4.5-hour window, the recent apixaban dose, and the imaging, how do you reason about IV thrombolysis versus thrombectomy alone?
Read the worked answer
Mechanical thrombectomy is clearly indicated: M1 occlusion, NIHSS ≥6, ASPECTS ≥6, and a favorable mismatch profile - this is a strong Level 1 indication regardless of the thrombolysis decision.
IV thrombolysis is the harder call:
- He is at 4.5 hours, at the edge of the standard window.
- Last apixaban dose was 14 hours ago; DOAC use within 48 hours is generally a contraindication unless coagulation testing (e.g., thromboelastography or a normal aPTT/anti-Xa) confirms no residual anticoagulant effect. Without that, giving IV alteplase/tenecteplase adds hemorrhagic risk on top of an already borderline core.
- The pragmatic answer: proceed directly to thrombectomy and do not delay reperfusion for thrombolysis; if a rapid DOAC assay is available and normal, thrombolysis could be reconsidered, but thrombectomy should not wait.
3. The patient's blood pressure is 178/96 mmHg. How does this affect your management in the thrombectomy pathway?
Read the worked answer
For patients going to mechanical thrombectomy, permissive hypertension up to 185/110 mmHg is acceptable and you should not aggressively lower pressure before reperfusion - collateral perfusion depends on it. So 178/96 does not by itself block the pathway.
If IV thrombolysis were given, you would need to bring BP below 185/110 before the bolus and keep it <180/105 afterward - he is already under that ceiling, so no pretreatment lowering is required for thrombolysis either. The judgment point is to avoid overtreating: do not chase a 'normal' pressure pre-thrombectomy, and anticipate that post-reperfusion you may need to lower pressure if there is successful recanalization with reperfusion injury risk.