A 78-year-old man with a past history remarkable only for gout is seen because of the acute onset of chest pain. He describes a 4-day prodrome of rhinorrhea, nonproductive cough, myalgias, and anorexia. Approximately 8 hours before he is seen in the emergency room (ER), he began to notice the gradual onset of sharp substernal chest pain, worse with inspiration, relieved by sitting up, and associated with diaphoresis.

The pain is slightly worse with exertion but is not relieved by sublingual nitroglycerin (NTG) administered in the ER, although morphine sulfate and oxygen do seem to alleviate his discomfort. His temperature is 101◦F (38.5◦C), his heart rate is 105 beats per minute and regular, his respiratory rate is 17 per minute, and his blood pressure is 105/65 mmHg. The remainder of the physical examination is normal. The electrocardiogram (ECG) is interpreted by the ER staff to show "sinus tachycardia with ST-segment elevations inferiorly and nonspecific ST- and T-wave changes elsewhere." An arterial blood gas determination performed on room air shows normal arterial oxygenation. The chest radiographic study is normal.

The ER staff starts an IV heparin drip and a platelet glycoprotein IIb-IIIa inhibitor infusion for the treatment of a presumed acute coronary syndrome (ACS) An IV NTG infusion and oxygen therapy are instituted but, despite these measures, the pain continues. The cardiac catheterization team is called to consider coronary angiography. Antacid therapy does not relieve the pain and only morphine sulfate seems to offer relief. Blood tests reveal a normal troponin, normal electrolytes, normal D-dimer, and normal renal function. The hemoglobin is normal but the white blood cell count is mildly elevated.

The patient is taken to the catheterization laboratory and his coronary angiogram reveals diffuse, mild, nonobstructive coronary artery disease (CAD). The IIb-IIIa inhibitor AQ3 is discontinued. When the patient is transferred to the coronary care unit, the ECG shows continued "evolution'' with ST-segment elevations of less than 2 mm in leads I, II, III, aVL, aVF, and V2 to V6 that do not respond to IV NTG. The patient's chest pain persists.

Further increments of NTG are given in an IV infusion and the patient's blood pressure begins to decrease. After 2 hours, the patient continues to writhe in pain, complains of feeling dizzy and having a severe headache, and vomits after the fifth dose of IV morphine sulfate. You are asked to see the patient and your examination reveals sinus tachycardia, a blood pressure of 82/50 mmHg (no pulsus paradoxus), a respiratory rate of 16 per minute, a temperature of 101◦F (38.5◦C), clear lung fields, and no elevation in the jugular venous pressure, but a three-component pericardial friction rub is heard over the precordium. The hemoglobin level is stable.

1. What is the most likely clinical diagnosis of this patient's chest pain?
2. On the basis of your clinical impression of this patient's presentation, what features would be expected on the ECG?
3. Is a normal troponin helpful in acute MI?
4. What is the most effective treatment for acute pericarditis?
5. What is the most likely cause of the hypotension in this patient?

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from Internal Medicine Casebook, 3e
Robert W Schrier MD
ISBN: 978-0-7817-6529-9