Contemporary Diagnosis and Management of Patients With Myocardial Infarction in the Absence of Obstructive Coronary Artery Disease: A Scientific Statement From the American Heart Association

Abstract

Myocardial infarction in the absence of obstructive coronary artery disease is found in ≈5% to 6% of all patients with acute infarction who are referred for coronary angiography. There are a variety of causes that can result in this clinical condition. As such, it is important that patients are appropriately diagnosed and an evaluation to uncover the correct cause is performed so that, when possible, specific therapies to treat the underlying cause can be prescribed. This statement provides a formal and updated definition for the broadly labelled term MINOCA (incorporating the definition of acute myocardial infarction from the newly released “Fourth Universal Definition of Myocardial Infarction”) and provides a clinically useful framework and algorithms for the diagnostic evaluation and management of patients with myocardial infarction in the absence of obstructive coronary artery disease.

Myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) was first documented >75 years ago when autopsy reports detailed myocardial necrosis in the absence of significant coronary atherosclerosis. The pioneering angiographic studies by DeWood et al reported a prevalence of nonobstructive coronary artery disease (CAD) in ≈5% of patients with acute myocardial infarction (AMI). This figure was subsequently confirmed in several large AMI registries5 and in a large meta-analysis in which 6% of AMIs occurred in the absence of obstructive CAD.

The term MINC or MINCA (myocardial infarction with normal coronary arteries) was initially coined to describe these patients and later evolved to MINOCA to encompass patients with evidence of atherosclerosis that is not considered sufficiently severe to compromise myocardial blood flow. Accordingly, MINOCA is initially considered at the time of angiography as a working diagnosis until further assessment excludes other possible causes for troponin elevation. The management of patients with MINOCA will vary depending on the underlying cause, for which an extensive evaluation should be undertaken in all patients.

Unfortunately, despite many reviews and a contemporary position statement from the European Society of Cardiology, some clinicians still suppose that the absence of obstructive CAD excludes the possibility of an AMI. Great variability exists in the manner in which patients with suspected MINOCA are evaluated and treated. The extent of the diagnostic and therapeutic strategies implemented often depends on local nonstandardized practices and varies according to hospital resources. Furthermore, there is no clear consensus in the medical community about how best to address situations in which local resources do not permit more advanced diagnostic testing. Finally, there is limited agreement regarding the long-term medical management of patients with MINOCA.

The purpose of this statement is to provide a formal and updated definition for the broadly labelled term MINOCA (incorporating the definition of AMI from the newly released “Fourth Universal Definition of Myocardial Infarction”) and to provide a clinically useful framework and algorithms pertaining to the diagnostic evaluation and management of these patients.