Mechanical Thrombectomy (Option B)
For a patient presenting at 12 hours with proximal anterior circulation occlusion and moderate-sized infarct core, mechanical thrombectomy is the most appropriate next step, provided advanced perfusion imaging confirms salvageable tissue with favorable mismatch criteria. 1
Why Thrombectomy is Indicated at 12 Hours
The patient falls within the extended 6-24 hour window where mechanical thrombectomy has proven efficacy when tissue selection criteria are met. The ESCAPE trial specifically enrolled patients up to 12 hours from onset with proximal anterior circulation occlusions and small-to-moderate infarct cores, demonstrating a common odds ratio of 2.6 (95% CI 1.7-3.8) for improved functional outcomes compared to standard care alone. 2 This trial showed 53.0% achieved functional independence versus 29.3% in controls, with reduced mortality (10.4% vs 19.0%). 2
Critical Imaging Requirements Before Proceeding
You must obtain CT perfusion or diffusion-weighted MRI with perfusion imaging to confirm salvageable tissue before initiating treatment. 1, 3 The patient needs to meet either:
- DAWN criteria: Clinical-imaging mismatch with specific age/NIHSS/core volume thresholds (age <80 with NIHSS ≥10 and core <31 mL, or NIHSS ≥20 and core <51 mL) 1
- DEFUSE-3 criteria: Ischemic core <70 mL, mismatch ratio ≥1.8, and mismatch volume ≥15 mL 1
- ASPECTS ≥6 on baseline imaging 4
Why Not tPA Alone (Option A)
tPA alone is contraindicated at 12 hours as this exceeds the 4.5-hour window for intravenous thrombolysis. 4 The standard tPA window cannot be extended to 12 hours regardless of imaging findings.
Why Not Combined tPA + Thrombectomy (Option D)
While combined therapy is the standard approach within the 4.5-hour window, at 12 hours the patient is beyond the time-based eligibility for IV tPA. 4 The 2015 AHA/ASA guidelines explicitly state that patients should receive IV r-tPA within 4.5 hours of onset according to professional society guidelines. 4 Even though 83.7-91.5% of patients in positive thrombectomy trials received IV tPA, this was because they presented within the tPA window. 1
Why Not Observation (Option C)
Observation would deny the patient a proven life-saving intervention. The ESCAPE trial demonstrated absolute mortality reduction of 8.6% with thrombectomy (10.4% vs 19.0%), and the number needed to treat for one additional patient to achieve functional independence is approximately 4. 2
Technical Execution Details
The angiographic goal must be TICI 2b/3 reperfusion to maximize functional outcomes. 1, 3 In the ESCAPE trial, stent retrievers were the primary device, achieving successful recanalization in 72.4% of cases. 4 The median time from CT to first reperfusion was 84 minutes, emphasizing the need for rapid workflow. 2
Minimize door-to-groin puncture time - the ESCAPE protocol targeted groin puncture within 60 minutes of CT/CTA completion. 4 Only blood glucose measurement is required before proceeding; do not delay for unnecessary testing. 5, 3
Absolute Contraindications at This Time Point
Do not proceed with thrombectomy if imaging demonstrates:
- ASPECTS of 0 (extensive irreversible damage) 5
- No perfusion mismatch (no salvageable tissue) 1, 5
- Large established infarct core >70 mL by DEFUSE-3 criteria or failure to meet DAWN criteria 1
Post-Procedure Management
Maintain blood pressure ≤180/105 mmHg for 24 hours after thrombectomy to reduce hemorrhagic complications. 1 Monitor closely for symptomatic intracranial hemorrhage, which occurred in only 3.6% of thrombectomy patients in ESCAPE. 2
Common Pitfall to Avoid
Do not wait to assess clinical response to IV tPA before pursuing thrombectomy - this is explicitly not recommended and delays definitive treatment. 4 However, in this case at 12 hours, IV tPA is not indicated regardless, making thrombectomy the sole reperfusion option if imaging criteria are met.