Role of optical coherence tomography in clinical management of myocardial infarction with nonobstructive coronary arteries

Abstract

Myocardial infarction without angiographic moderate to severe stenosis (> 50%) and any other related diagnosis on clinical presentation is defined as myocardial infarction with nonobstructive coronary arteries (MINOCA). Common causes of MINOCA working diagnosis includes plaque disruption, spontaneous coronary artery dissection, coronary artery spasm, coronary thromboembolism, Takotsubo cardiomyopathy, and myocarditis. Clinical history, assay of myocardial enzymes, electrocardiogram, echocardiography, coronary angiography, and left ventriculography facilitate the initial diagnosis of MINOCA and reveal the underlying causes, while cardiovascular magnetic resonance and optical coherence tomography (OCT) are used to confirm the diagnosis. Although cardiovascular magnetic resonance is the gold standard noninvasive diagnostic tool for MINOCA, its ability to diagnose the cause and mechanism underlying this condition in the coronary arteries is limited because of its image resolution. Observational studies have demonstrated that OCT can be used to determine the underlying cause of MINOCA by investigating the characteristics of the culprit lesions and to predict the prognosis of the patients. In this article, we review the current diagnostic approach for MINOCA focusing on each imaging tool. Furthermore, we reevaluate the role of OCT in the clinical management of MINOCA. Identifying the cause of MINOCA through OCT might help select optimal and effective drug treatments and improve prognosis.

Figure 1

Diagnostic algorithm for MINOCA. Diseases in which cardiac troponin levels are elevated due to noncardiac causes, such as sepsis and pulmonary artery thromboembolism, are excluded (red). In suspected MINOCA cases (light blue), IVUS/OCT, acetylcholine provocation testing, and CMR are used to rule out non-ischemic heart diseases like Takotsubo cardiomyopathy and myocarditis. Thus, a true diagnosis of MINOCA is obtained (green). CAD: coronary artery disease; CMR: cardiovascular magnetic resonance; ECG: electrocardiogram; IVUS: intravascular ultrasound; MINOCA: myocardial infarction with nonobstructive coronary arteries; OCT: optical coherence tomography; SCAD: spontaneous coronary artery dissection.

Figure 2

Left ventriculography of Takotsubo cardiomyopathy. Left ventriculography during the acute stage of Takotsubo cardiomyopathy shows apical ballooning (A: systole, B: diastole). Typical apical ballooning was observed during diastole.

Figure 3

Coronary spasm provocative testing. Changes in coronary angiograms of the left coronary artery. (A): Pre-acetylcholine, normal coronary; and (B): during intracoronary acetylcholine infusion, 99% stenosis of the left anterior descending.

Figure 4

Representative optical coherence tomography images. (A): Lipid plaque; (B): fibrous plaque; (C): red thrombus; (D): white thrombus; (E): plaque rupture; (F): plaque erosion; and (G): calcified nodule.

Figure 5

Coronary angiography and OCT in MINOCA. (A & B): Coronary angiography of a patient diagnosed with MINOCA. Coronary angiography showed no stenosis > 50%, but OCT revealed a thrombus in the main trunk of the left coronary artery. (A) right anterior oblique 30°/caudal 20°, (B) right anterior oblique 0°/cranial 30°; and (C): OCT image of the main trunk of the left coronary artery. Asterisk represents thrombus in the main trunk of the left coronary artery. MINOCA: myocardial infarction with nonobstructive coronary arteries; OCT: optical coherence tomography.