Chest Pain, Negative Troponins, and Renal Impairment
58-year-old man presents to the ED with 2 hours of substernal pressure and diaphoresis. He has type 2 diabetes, hypertension, and a 30-pack-year smoking history; there is no known coronary disease. ECG is normal, and high-sensitivity troponin is negative at 0 and 3 hours. He is afebrile, heart rate 78 and regular, blood pressure 146/88. eGFR is 34 mL/min/1.73 m². Five years ago he had urticaria without airway compromise after iodinated contrast. BMI is 38. He is pain-free now and can walk briskly without symptoms. The ED wants to admit him for “rule-out” and asks whether CT coronary angiography, exercise stress testing, or invasive angiography is best. There is no prior cardiac imaging. The catheterization lab is available, but the team is concerned about contrast-associated acute kidney injury.
1. Which test is most appropriate after shared decision-making? Justify using pretest probability, renal function, and allergy history.
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His pretest probability is intermediate: typical symptoms and multiple risk factors, but normal ECG and negative serial troponins. In that setting, CCTA is reasonable and can exclude CAD noninvasively; invasive angiography is not first-line because it is invasive and may find nonobstructive disease. eGFR 34 is not an absolute contraindication, but requires hydration and minimum contrast volume. His prior reaction was mild urticaria, so premedication with a corticosteroid and antihistamine is appropriate. If he cannot control heart rate or has irregular rhythm, stress imaging may be better. The choice should be shared and should include the downstream implications of a nondiagnostic study.
2. CCTA shows a 50–70% mid-LAD stenosis but severe motion artifact; the distal vessel is not evaluable. What next?
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A 50–70% stenosis with severe motion artifact is nondiagnostic, so the CCTA cannot be used to rule out flow-limiting disease. The next step is functional testing-exercise stress echocardiography, SPECT/PET myocardial perfusion, or stress cardiac MRI-or invasive coronary angiography if symptoms are ongoing or high-risk features develop. I would not reassure him on the basis of a non-evaluable segment. The choice depends on local expertise, whether he can exercise, and whether additional anatomy is needed.
3. If CCTA is chosen, outline contrast and renal precautions.
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Before contrast: premedicate for prior urticaria, use isotonic saline hydration, choose low-osmolar contrast, and limit volume. Avoid NSAIDs and other nephrotoxins. Check creatinine before and after, and do not withhold metformin solely for eGFR >30 unless there is acute kidney injury. Have anaphylaxis equipment available. Document the reaction history. If renal function worsens or the patient cannot be hydrated, reconsider stress testing.