Ischemic Stroke vs Transient Ischemic Attack

Why IV alteplase 0.9 mg/kg is correct

• IV alteplase 0.9 mg/kg given within 4.5 hours of symptom onset reduces 90-day disability (modified Rankin scale) by 30%.
• This patient arrived at 2.5 hours with no hemorrhage on CT, no large territory infarct, NIHSS of 14, and no stated contraindications — all criteria are met.

Why the others are wrong

• IV heparin infusion — IV heparin is not indicated for acute ischemic stroke and increases bleeding risk without proven benefit (right-concept-wrong-drug).
• Aspirin 325 mg orally immediately — aspirin is started 24 hours after tPA, not before, to avoid compounding hemorrhagic risk (wrong-timing).
• Aspirin plus clopidogrel loading dose — dual antiplatelet therapy is used for high-risk TIA or minor ischemic stroke (POINT/CHANCE trials), not as a substitute for thrombolysis in a patient eligible for alteplase (confused-with minor-stroke protocol).

Additional high-yield points

• Time is brain: 1.9 million neurons are lost per minute of ischemia.
• Absolute contraindications to alteplase include hemorrhage on CT, prior intracerebral hemorrhage (ICH), systolic blood pressure (SBP) above 185 or diastolic blood pressure (DBP) above 110, platelets below 100K, anticoagulants with therapeutic INR above 1.7, and active bleeding.
• Mechanical thrombectomy (MT) is indicated for large vessel occlusion (LVO) involving the internal carotid artery (ICA), M1, or basilar artery, with NIHSS above 6, within 24 hours (extended window with perfusion imaging per DAWN/DEFUSE-3 trials); MT plus tissue plasminogen activator (tPA) is superior to tPA alone for LVO.
• Tenecteplase 0.25 mg/kg IV bolus is non-inferior to alteplase, simpler to administer as a single bolus, and increasingly used.

Why Carotid duplex ultrasonography is correct

• A transient ischemic attack is a warning event, not a benign one - the risk of stroke is about 5 percent at 2 days and 10 percent at 90 days, and most of that risk is front-loaded.
• The 2021 AHA/ASA secondary prevention guideline recommends noninvasive imaging of the cervical vessels routinely and promptly, ideally within 48 hours, because carotid endarterectomy performed within 2 weeks for a symptomatic 70 to 99 percent stenosis produces a large absolute reduction in recurrent stroke, with a number needed to treat of roughly 6 based on NASCET.
• Carotid duplex ultrasonography — noninvasive, inexpensive, and the standard first-line study of the extracranial carotids in a patient with anterior circulation symptoms and atherosclerotic risk factors.

Why the others are wrong

• Transcranial Doppler ultrasound — insonates the intracranial arteries and can detect intracranial stenosis or microembolic signals, but it does not image the carotid bifurcation, the lesion whose revascularization within 2 weeks creates the urgency here.
• Transesophageal echocardiography — useful for a suspected cardioembolic source such as intracardiac thrombus, vegetation, or aortic arch atheroma, but it is a second-tier study after vascular imaging and cardiac rhythm monitoring.
• Catheter cerebral angiography — the anatomic reference standard, but invasive with roughly a 1 percent periprocedural stroke risk, so it is reserved for discordant or nondiagnostic noninvasive studies.

Prolonged cardiac monitoring for atrial fibrillation, a lipid panel, and HbA1c complete the preventive workup.