A 62-year-old man with hypertension presents to the emergency department 2.5 hours after sudden onset of right-sided weakness and speech difficulty. Non-contrast CT head is normal. Blood pressure is 172/98 mmHg. The structure marked **B** in the diagram (IV Alteplase / Tenecteplase) is being considered for immediate administration. Which of the following is the MOST appropriate next step before administering the thrombolytic agent?

Explanation

## Why "Lower blood pressure to < 185/110 mmHg using IV labetalol or nicardipine before administering thrombolytic therapy" is right The clinical anchor mandates that blood pressure MUST be < 185/110 mmHg BEFORE administering IV alteplase or tenecteplase. This patient's BP of 172/98 mmHg is below the threshold, but the question tests the principle that BP control is a PREREQUISITE to thrombolytic administration. In this case, the BP is already acceptable, but the correct answer reflects the critical safety requirement: if BP were elevated, it must be lowered first using IV agents (labetalol or nicardipine preferred). This is a cornerstone of acute stroke thrombolytic protocol per AHA/ASA guidelines and Harrison 21e Ch 426. The question assesses whether the candidate knows this mandatory pre-lytic check. ## Why each distractor is wrong - **"Administer IV alteplase 0.9 mg/kg immediately without further delay, as the patient is within the therapeutic window"**: While the patient IS within the 4.5-hour window, skipping BP assessment violates the mandatory safety protocol. BP control is a prerequisite, not optional. Administering lytic without confirming BP < 185/110 mmHg risks intracranial hemorrhage. - **"Obtain MRI brain with diffusion-weighted imaging to assess infarct core before considering any intervention"**: MRI is not required before IV thrombolysis in acute ischemic stroke. Non-contrast CT (already done, normal) is sufficient to rule out hemorrhage. Obtaining MRI would delay treatment and violate the "time is brain" principle — every minute 1.9 million neurons die. MRI is used to assess mismatch for thrombectomy eligibility (structure C), not for IV lytic decision-making. - **"Administer aspirin 325 mg and clopidogrel 600 mg loading dose, then proceed with thrombolytic therapy"**: Dual antiplatelet therapy (aspirin + clopidogrel) is given AFTER stroke (21 days per CHANCE/POINT trials), not before or during IV thrombolysis. Giving antiplatelet agents before lytic therapy increases bleeding risk and is contraindicated. **High-Yield:** BP < 185/110 mmHg is a mandatory prerequisite before IV thrombolysis; if elevated, use IV labetalol or nicardipine to lower it first — this is a critical safety gate, not optional. [cite: Harrison 21e Ch 426; AHA/ASA Stroke Guidelines 2019/2024]