Crushing chest pain at a soum health center
A 58-year-old male herder is brought to a soum health center at 06:00 with two hours of crushing substernal chest pressure radiating to the left jaw, nausea and sweating. He has smoked 20 cigarettes daily for 30 years, has treated hypertension and no known diabetes. He looks pale and anxious. Blood pressure is 150/95 mmHg, pulse 92/min and regular, respiratory rate 22/min, SpO2 94% on room air, temperature 36.6°C. Bibasilar crackles are heard. The health center has a 12-lead ECG, oxygen, aspirin, clopidogrel, nitroglycerin, morphine, IV fluids and a basic emergency kit, but no troponin assay and no CT. The nearest PCI-capable hospital is a 4-hour drive on winter roads; weather may close the road. ECG shows 3 mm ST elevation in leads II, III and aVF with reciprocal depression in I and aVL. The physician must decide whether to treat locally and transfer, or transfer immediately.
1. What is the most likely diagnosis, and which immediate drug and monitoring decisions are most important in this setting? Explain your reasoning.
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The ECG is diagnostic of an acute inferior ST-elevation myocardial infarction until proven otherwise. The priority is not to wait for troponin, which is unavailable and would only delay reperfusion. I would give aspirin 300 mg chewed, add a P2Y12 inhibitor and anticoagulation according to the local protocol, obtain IV access, apply continuous ECG monitoring, and arrange transfer. Oxygen is indicated only for hypoxemia, targeting SpO2 above 90%, because routine oxygen in normoxemic patients is not helpful. Nitrates require particular caution in inferior MI: right ventricular involvement can make perfusion preload-dependent, so nitroglycerin may cause severe hypotension. I would avoid nitrates if systolic pressure is below 90 mmHg, if right ventricular infarction is suspected, or if a phosphodiesterase inhibitor was recently used. Morphine only for refractory pain, cautiously. Monitor for bradyarrhythmia and heart block, which are common in inferior infarction.
2. The road is open and transfer will take 4 hours. Streptokinase is available. Would you give fibrinolysis? What would make you withhold it, and what must happen afterward?
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I would give fibrinolysis if there are no contraindications, because primary PCI cannot be achieved within 120 minutes and symptom onset is under 12 hours with clear ST elevation. Streptokinase 1.5 million units IV over about 60 minutes should be started promptly with continuous monitoring. I would withhold it for prior streptokinase exposure, recent stroke, active bleeding, recent surgery or trauma, severe uncontrolled hypertension, suspected aortic dissection, or pregnancy. Inferior MI with hypotension or right ventricular infarction is a relative hazard because lysis and vasodilation can further reduce preload; cautious fluid resuscitation first is important. After lysis, the patient still needs transfer for reperfusion assessment, rescue PCI if there is no clinical evidence of reperfusion, and management of complications. Document symptom onset, drug times, blood pressure and rhythm throughout.