Acute Coronary Syndrome with Normal or Near Normal Coronary Arteries (ACSNNOCA): Should we be Worried?

Abstract

In patients presenting with Acute coronary syndrome, 6-10% of MI and 10-25% of non MI ACS have normal or near-normal (non-significant i.e <50% stenosis) coronary arteries at coronary angiography. This important but heterogeneous subset of younger patients, commonly females, may have lower risk of cardiovascular events compared to patients with obstructive coronary artery disease but the risk is still substantial and hence needs further investigations to identify the underlying cause and devise a proper treatment strategy. Coronary angiography is the first step. Left ventricular angiogram, intravascular imaging and vascular reactivity testing may be done to identify other diagnostic possibilities. Less risky non-invasive tests such as echocardiography and cardiac magnetic resonance imaging may also effectively identify the cause of ACSNNOCA and guide management in some cases. This article aims at summarizing the pathophysiology, diagnosis and management of ACSNNOCA. Abbreviations: ACSNNOCA = acute coronary syndromes with normal or non-obstructive coronary arteries; CAD = coronary artery disease; MB = myocardial bridging; MI = myocardial infarction; MINCA = myocardial infarction with normal coronary arteries; MINOCA = myocardial infarction with non- obstructive coronary arteries; MVD = microvascular dysfunction; NSTE = non-ST elevation; NSTEMI = non-ST elevation myocardial infarction; SCAD = spontaneous coronary dissection; STEMI = ST elevation myocardial infarction.