A Patient With MINOCA
A 53-year-old woman with hypertension, hyperlipidemia, anxiety disorder, and a remote surgical history of bilateral salpingo-oophorectomy presented with chest pain. She was in her usual state of good health until the day of admission, when she developed chest discomfort while moving furniture in her apartment. She reported that her symptoms were sub-sternal, left-sided, and 7/10 in severity, with chest pain radiating to her left arm and jaw. She also reported mild dyspnea and an episode of nausea. The symptoms lasted 30 minutes and gradually resolved with rest. She activated emergency medical services and was brought to the hospital by ambulance for further evaluation.
In the emergency department, the patient was free of chest pain. Physical examination was notable for an overweight woman in no acute distress. Body temperature was 98.6 F˚, pulse was 102 bpm, blood pressure was 153/78, respiratory rate was 14 breaths per minute, and oxygen saturation was 100% on room air. Cardiovascular examination revealed a normal S1 and S2 without murmurs, rubs, or gallops. There was no jugular venous distention or lower extremity edema. Pulses were 2+ and symmetric.
The initial troponin-I was elevated to 3.13 ng/mL. Complete blood count revealed a mild leukocytosis of 11.6 k/uL, hemoglobin of 13.0 g/dL, and platelets of 192 K/uL. A comprehensive metabolic panel was notable for normal renal function with a blood urea nitrogen of 11 and a creatinine of 0.6. Total cholesterol was 211 mg/dL (high-density lipoprotein cholesterol of 41 mg/dL, low-density lipoprotein cholesterol of 137 mg/dL, and triglycerides of 163 mg/dL).
Electrocardiography in the emergency department revealed normal sinus rhythm with no significant ST-segment or T-wave changes. No cardiopulmonary pathology was evident on a chest radiograph. Echocardiography was notable for a left ventricular (LV) ejection fraction of 55%, with hypokinesis of the basal interventricular septum. There was no significant valvular disease.
Based on her clinical presentation, the patient was diagnosed with myocardial infarction (MI), and 325 mg of aspirin, 300 mg of clopidogrel, and a high-intensity statin were administered. She was referred for invasive coronary angiography.
Invasive coronary angiography revealed angiographically normal right coronary (Figure 1) and left main and circumflex arteries (Figure 2). There was mild coronary artery disease in the proximal left anterior descending artery (LAD). The LV end diastolic pressure was <5 mmHg. A diagnosis of MI with nonobstructive coronary arteries (MINOCA) was established.
Figure 1: Coronary Angiography of the Right Coronary Artery System in the Left Anterior Oblique View With Slight Cranial Angulation
Figure 2: Coronary Angiography of the Left Coronary Artery System in the Right Anterior Oblique View With Cranial Angulation
Which of the following diagnostic steps is the most appropriate to establish the mechanism of MINOCA?