2026 AHA/ASA UPDATE
Emergency Briefcase · Case Mode

Acute Ischemic Stroke

Recognition, imaging, modern thrombolysis windows and thrombectomy—built around the decisions that change disability.

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The Case

Arrival

A 68-year-old woman develops sudden aphasia and right arm weakness while eating breakfast. EMS reports last known well 07:40; ED arrival is 09:05. BP 198/112, glucose 122 mg/dL, NIHSS 11. She takes no anticoagulant.

Immediate priorities

  • Activate the stroke pathway
  • ABCs, glucose, exact last-known-well
  • Focused neurologic exam/NIHSS
  • Noncontrast CT and emergent vascular imaging
  • Do not delay reperfusion for routine ECG or troponin

ABEM-style decision 1

What is the best next action?

Best answer: B. The patient has a disabling deficit inside the standard IV thrombolysis window. BP must be ≤185/110 before IVT; imaging must exclude hemorrhage and identify an LVO without unnecessary delay.
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BE-FAST Assessment

Mark the findings present. Any positive focal sign warrants immediate stroke evaluation.

Critical action

Do not let a low NIHSS obscure a disabling deficit. Aphasia, hemianopia, dominant-hand weakness and severe gait dysfunction may be disabling despite a modest score.

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Image for Hemorrhage, Core and Vessel

Noncontrast CTExclude hemorrhage and assess early ischemic change. Do not delay standard-window IVT for advanced imaging in an otherwise eligible patient.
CTA head and neckIdentify LVO and plan EVT. In suspected LVO, vascular imaging should not be delayed solely to obtain serum creatinine.
Advanced selectionCT/MR perfusion or MRI DWI–FLAIR mismatch can select certain wake-up, unknown-onset and 4.5–9-hour patients for IV thrombolysis.

ABEM-style decision 2

CT shows no hemorrhage. The patient remains aphasic with arm weakness. Which statement is most accurate?

Best answer: C. Standard-window treatment is time-critical and does not require advanced imaging selection. CTA/LVO evaluation should occur rapidly without delaying eligible IVT.
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The Updated Thrombolysis Window

The headline

“tPA ends at 4.5 hours” is no longer an adequate teaching statement. The standard window remains ≤4.5 hours, but selected patients with unknown onset or 4.5–9 hours from onset/last known well may receive IV thrombolysis when advanced imaging demonstrates favorable mismatch.

0–4.5 hStandard window

Alteplase or tenecteplase for eligible adults with disabling deficits. Treat rapidly; advanced imaging selection is not required.

Unknown onsetImaging-selected

MRI DWI–FLAIR mismatch can support IVT. Automated perfusion mismatch may also select appropriate wake-up patients.

4.5–9 hExtended window

IVT may be reasonable when automated perfusion imaging demonstrates salvageable penumbra. Wake-up patients may qualify when within 9 hours of the midpoint of sleep.

Important boundary

This is not blanket thrombolysis through 9 or 24 hours. Extended-window IVT is imaging-selected and protocol-dependent. EVT eligibility may extend to 24 hours and must be assessed independently; IVT evaluation must not delay thrombectomy.

ABEM-style decision 3

A patient awakens at 06:30 with disabling aphasia; last known well was 22:30. What is the most appropriate next step after noncontrast CT excludes hemorrhage?

Best answer: D. Wake-up stroke is not automatically outside reperfusion eligibility. DWI–FLAIR or perfusion mismatch may support extended-window IVT, and CTA evaluates for thrombectomy-eligible LVO.
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Thrombolytic Dosing

2026 standard-window choices

  • Tenecteplase: 0.25 mg/kg IV single bolus, max 25 mg
  • Alteplase: 0.9 mg/kg IV, max 90 mg; 10% bolus, remainder over 60 min

Agent selection in extended windows should follow the local stroke protocol and stroke-team recommendation.

Dose calculator

Tenecteplase: 20 mg IV once.

BP threshold

Before IVT: ≤185/110 mm Hg. After IVT: maintain ≤180/105 mm Hg. Intensive SBP lowering below 140 after reperfusion is not recommended and may cause harm after EVT.

ABEM-style decision 4

An eligible 100-kg patient will receive tenecteplase. What dose is correct?

Best answer: A. Tenecteplase is 0.25 mg/kg with a 25-mg maximum. Do not use the myocardial-infarction weight-tiered dose.
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Endovascular Thrombectomy

Anterior circulation

EVT is recommended for appropriate proximal anterior-circulation LVO within 6 hours and for selected patients from 6–24 hours based on vessel, imaging, clinical severity, prestroke function and core characteristics.

Posterior circulation

The 2026 guideline strongly recommends EVT for selected basilar artery occlusion patients within 24 hours, including NIHSS ≥10 and favorable imaging criteria.

Critical action

Do not withhold otherwise indicated IVT just because EVT is planned, and do not allow IVT decisions to delay transfer or thrombectomy workflow.

ABEM-style decision 5

CTA reveals an M1 occlusion. The patient is IVT-eligible at 2 hours. Which strategy is best?

Best answer: B. Bridging thrombolysis should be delivered when indicated while thrombectomy proceeds without delay. Clinical improvement should not interrupt LVO workflow without stroke-team reassessment.
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Case Recap

ABEM decisions
0/5 correct

Critical actions

  1. Record exact last known well and disabling deficit.
  2. CT immediately; obtain CTA rapidly when LVO is suspected.
  3. Treat eligible disabling stroke within 4.5 hours without advanced-imaging delay.
  4. Use mismatch imaging for unknown-onset or 4.5–9-hour IVT selection.
  5. Evaluate EVT eligibility independently through 24 hours.

Common mistakes → mitigation

  • “NIHSS too low”: judge disability, not score alone.
  • “Past 4.5, nothing to do”: activate advanced imaging and EVT pathways.
  • Waiting for creatinine: do not delay emergent CTA for suspected LVO.
  • Wrong TNK dose: 0.25 mg/kg, max 25 mg.
  • Serial delay: run BP, imaging, IVT and transfer workstreams in parallel.
Emergency Briefcase · Updated September 2026