A 55-year-old woman with a past medical history of hypertension presents to the emergency room with progressive chest pain for the past week, worse with exertion, leading up to the day of presentation. Vitals on presentation are notable for temperature 37.3 C, heart rate 108, blood pressure 110/82, SpO2 98% on room air. On examination her lungs are clear, regular rate and rhythm with no murmurs, abdomen is soft, 1+ pitting edema of the lower extremity. Labs are notable for a high-sensitivity troponin elevation on presentation to 250 pg/mL, increasing slightly to 300 pg/mL on recheck (assume reference range 0 – 20 pg/mL for this assay). The patient's electrocardiogram exhibits diffuse ST depressions. She is given aspirin 325 mg and nitroglycerin without resolution of chest pain. She is taken for coronary angiography which shows nonobstructive coronary artery. The patient is admitted for further work-up.
Which test or procedure is the most appropriate to pursue next in the diagnosis of this patient's care?
Show Answer
The correct answer is: C. Cardiac Magnetic Resonance Imaging (MRI)
This patient is presenting with myocardial infarction with nonobstructive coronary arteries (MINOCA). MINOCA is defined as myocyte injury secondary to an ischemic etiology, and obstructive coronary artery disease (CAD) must be ruled out.1,2 MINOCA is estimated to be present in 6-15% of patients with MI and is more common in women than men. Therefore, after obstructive disease has been excluded, it is important to rule out nonischemic causes of myocyte injury, such as cardiomyopathy or myocarditis. Cardiac MRI is given a Class 1B recommendation by the 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guideline for the evaluation and diagnosis of chest pain for this purpose, and specifically suggested to be performed within 2 weeks of acute coronary syndrome.3,4
Answer A, CCTA, is incorrect. While a helpful test in the assessment of CAD and vessel lumen stenosis, as well as providing information on high-risk plaque features, obstructive disease has already been ruled out via coronary angiography.
Answer B, SPECT, is incorrect. Functional testing such as SPECT may be helpful in diagnosing ischemia initially but will not provide as much information on nonischemic etiologies of chest pain as cardiac MRI.
Answer D, technetium pyrophosphate scintigraphy, is a highly specific test for cardiac amyloidosis. While infiltrative cardiomyopathies may lead to chest pain and troponin elevation, this would not be the best next test.
References
Thygesen, K, Alpert JS, Jaffe AS, et al; Executive Group on behalf of the Joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/American Heart Association (AHA)/World Heart Federation (WHF) Task Force for the Universal Definition of Myocardial Infarction. Fourth universal definition of myocardial infarction (2018). Circulation 2018;138:e618-e651.
Dastidar AG, Baritussio A, De Garate E, et al. Prognostic role of CMR and conventional risk factors in myocardial infarction with nonobstructed coronary arteries. JACC Cardiovasc Imaging 2019;12:1973-82.
Ferreira VM. CMR should be a mandatory test in the contemporary evaluation of "MINOCA". JACC Cardiovasc Imaging 2019;12:1983-86.
Gulati M, Levy PH, Mukherjee E, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guideline for the evaluation and diagnosis of chest pain: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. J Am Coll Cardiol 2021;78:e187-e285.
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