Abstract 18714: Myocardial Infarction With Non-Obstructive Coronary Artery Disease in a Young Woman - The Cardinal Role of Coronary Reactivity Testing in Unveiling the Underlying Etiology

Abstract

43-year old female presented to the emergency department with substernal chest pain. She had similar symptoms years ago without obstructive CAD on coronary angiogram and was diagnosed with myocarditis. Presenting ECG revealed new anterolateral T wave inversions (Fig 1), and high-sensitivity troponins peaked at 322 ng/L consistent with NSTEMI. TTE was significant for global hypokinesis of the left ventricle with a reduced ejection fraction of 35 to 40%. Invasive coronary angiogram showed no obstructive CAD or spontaneous coronary artery dissection however there was reduced flow in the mid to distal LAD raising suspicion for endothelial and microvascular dysfunction. Contrast-enhanced cardiac MRI showed myocardial edema in the anterior and anteroseptal walls with elevated myocardial T1 and T2 values, and early enhancement post gadolinium administration showed an acute LAD territorial infarct (Fig 2). Findings were consistent with myocardial infarction with non-obstructive coronary artery disease (MINOCA). She was started on carvedilol for empiric treatment of coronary artery spasm and microvascular dysfunction, along with aspirin and atorvastatin. Losartan was added for heart failure management. Outpatient invasive coronary reactivity testing showed severe epicardial (70% vasoconstriction) and microvascular (80% decrease in coronary blood flow) endothelial dysfunction in response to acetylcholine (Fig 3 and Fig 4) as underlying etiology of recent MINOCA. CFR was normal. L-arginine (NO precursor) was added to the medical regimen. Patient has not had recurrence of chest pain or ACS at 1 year follow-up and LVEF normalized on repeat echocardiogram. This case shows the importance of cardiac MRI in confirming the diagnosis of MINOCA in patients with no obstructive CAD, and the crucial role of coronary reactivity testing in diagnosing and treating severe coronary endothelial dysfunction, which is aligned with the AHA/ACC MINOCA consensus document.