A 55-year-old man presents with BP 235/140 mmHg, chest pain, and an ECG showing new ST changes. Troponin is mildly elevated. He has acute hypertensive emergency with presumed type 2 myocardial infarction. Which antihypertensive is the MOST appropriate intravenous agent, and what is the BP reduction target in the first hour?

• A Sodium nitroprusside; reduce BP by 50% within 1 hour
• B Oral nifedipine; immediate sublingual administration to rapidly lower BP
• C IV hydralazine; reduce BP to normal levels (120/80 mmHg) within 2 hours
• D Nicardipine or labetalol; reduce mean arterial pressure (MAP) by ≤25% in first hour, then gradually to 160/100 mmHg over next 2–6 hours ✓

Explanation

In hypertensive emergencies with myocardial injury, the target is to reduce MAP by no more than 25% in the first hour (to avoid coronary, cerebral, or renal ischaemia from autoregulatory breakthrough), then progressively to 160/100–110 mmHg over the next 2–6 hours. IV nicardipine (calcium channel blocker, titratable) or IV labetalol (combined alpha/beta blocker) are preferred for ACS-associated hypertensive emergencies; labetalol reduces cardiac workload without reflex tachycardia. Sublingual nifedipine is contraindicated (precipitous uncontrolled BP drop, MI risk). Sodium nitroprusside causes cyanide toxicity with prolonged use and reflex tachycardia.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.