In a 50‑year‑old patient with acute ischemic stroke presenting 7 hours after symptom onset, CT perfusion shows an infarct core of approximately 20 mL and a perfusion mismatch ratio of 8, with an occlusion of the A2 segment of the anterior cerebral artery, what is the recommended acute treatment?

Management of A2 Occlusion at 7 Hours with Suboptimal Perfusion Mismatch

This patient should receive best medical management without mechanical thrombectomy, because the A2 segment is a distal vessel that falls outside guideline-supported targets for late-window endovascular therapy, and the mismatch ratio of 8—while seemingly large—does not overcome the fundamental limitation that thrombectomy for distal anterior cerebral artery occlusions lacks evidence of benefit even in the early window. 1, 2

Why Mechanical Thrombectomy Is Not Indicated

Vessel Location Excludes Late-Window Thrombectomy

• The 2018 AHA/ASA guidelines restrict late-window (6–24 hour) thrombectomy to patients with proximal anterior-circulation large-vessel occlusions—specifically internal carotid artery or M1 segment of the middle cerebral artery—who meet DAWN or DEFUSE-3 criteria. 1, 3
• A2 segment occlusions are distal vessels that do not qualify as large-vessel occlusions for the purpose of extended-window thrombectomy. 2
• Even proximal M2 occlusions carry only a Class IIb (may be reasonable) recommendation with Level B-R evidence in the early window, with a pooled odds ratio of 1.28 (95% CI 0.51–3.21) that failed to reach statistical significance in the HERMES meta-analysis. 2
• The ESCAPE, EXTEND-IA, and SWIFT PRIME trials that established the benefit of thrombectomy enrolled patients with ICA or proximal MCA occlusions, not distal vessels like A2. 3

Mismatch Ratio Does Not Compensate for Distal Location

• Although the mismatch ratio of 8 appears favorable, DEFUSE-3 required not only a mismatch ratio ≥1.8 but also a proximal large-vessel occlusion as a prerequisite; the A2 location disqualifies this patient regardless of perfusion parameters. 1
• The small 20 mL core is favorable, but no trial has validated thrombectomy for distal anterior cerebral artery occlusions even with excellent perfusion imaging. 3

Natural History Favors Conservative Management

• Distal occlusions, including A2 segments, have higher rates of spontaneous recanalization with medical therapy compared to proximal large-vessel occlusions. 2
• The risk-benefit balance for thrombectomy in distal vessels is unfavorable because procedural complications (vessel perforation, dissection) may outweigh uncertain benefit. 3

Why Intravenous Alteplase Is Contraindicated

• Intravenous alteplase is approved only within 4.5 hours of symptom onset; at 7 hours, this patient is beyond the therapeutic window. 3, 2
• The WAKE-UP trial extended the window using DWI-FLAIR mismatch, but that applies only to wake-up strokes with unknown onset time, not to patients with a known 7-hour delay. 3

Recommended Standard Medical Management

Immediate Antiplatelet Therapy

• Initiate aspirin 160–325 mg orally immediately. Do not delay aspirin while awaiting potential intervention that will not occur. 1, 2

Blood Pressure Management

• Maintain systolic blood pressure ≤180 mm Hg and diastolic ≤105 mm Hg in patients not receiving reperfusion therapy. 1, 2
• Avoid aggressive blood pressure reduction, which may worsen perfusion to the penumbra. 1

Neurological Monitoring

• Perform serial neurological examinations every 15 minutes for the first 2 hours, then hourly thereafter. 1, 2
• Admit to a dedicated stroke unit with continuous cardiac monitoring to detect arrhythmias (especially atrial fibrillation) that may influence secondary prevention. 2, 4

Imaging Surveillance

• Obtain a repeat non-contrast head CT at 24 hours (or sooner if clinical deterioration occurs) to assess for hemorrhagic transformation or infarct expansion. 1, 2
• Monitor closely for signs of malignant cerebral edema, though this is less common with A2 territory infarcts than with large MCA strokes. 1

Critical Pitfalls to Avoid

Do Not Extend Thrombectomy Criteria Beyond Evidence

• Do not attempt to extrapolate DAWN or DEFUSE-3 eligibility to distal vessels; doing so exposes patients to procedural risks without proven benefit. 1
• The 2018 guidelines explicitly state that only patients meeting strict trial criteria should receive late-window thrombectomy; all others should receive standard medical therapy. 1, 3

Do Not Delay Aspirin

• Do not postpone aspirin administration while awaiting possible intervention. Early antiplatelet therapy improves outcomes when reperfusion is not indicated. 1

Recognize Limitations of Perfusion Imaging

• While the mismatch ratio of 8 suggests substantial salvageable tissue, perfusion imaging was designed to select patients for proximal large-vessel occlusion thrombectomy, not to justify intervention in distal vessels. 3
• The presence of penumbra does not mandate thrombectomy if the vessel location and time window fall outside validated indications. 1

Secondary Prevention Planning

• Investigate stroke mechanism promptly (echocardiography, prolonged cardiac monitoring, vascular imaging of neck vessels) to guide secondary prevention. 4, 5
• Initiate statin therapy and optimize vascular risk factor control (diabetes, hypertension, smoking cessation). 4
• If atrial fibrillation is detected, transition from aspirin to anticoagulation after confirming absence of hemorrhagic transformation on 24-hour imaging. 4