From the Guidelines
Myocardial infarction with non-obstructive coronary arteries (MINOCA) is distinct from Non-obstructive coronary artery disease (NOCA) in that MINOCA refers to a clinical syndrome where a patient presents with symptoms and evidence of myocardial infarction, but without obstructive coronary artery disease (>50% stenosis) on angiography.
Key differences between MINOCA and NOCA
- Definition: MINOCA is a working diagnosis that requires the presence of myocardial infarction (as evidenced by elevated troponin levels and clinical symptoms) and non-obstructive coronary arteries on angiography 1, whereas NOCA refers to the absence of obstructive coronary artery disease.
- Clinical presentation: MINOCA patients present with symptoms suggestive of ischemia, such as chest pain, and may have electrocardiographic changes or imaging evidence of myocardial injury 1.
- Diagnostic criteria: The diagnosis of MINOCA is made based on the presence of myocardial infarction, non-obstructive coronary arteries, and the absence of an alternate diagnosis for the clinical presentation 1.
- Pathophysiology: MINOCA can be caused by a variety of mechanisms, including epicardial coronary artery disorders, imbalance between oxygen supply and demand, coronary endothelial dysfunction, and myocardial disorders without involvement of the coronary arteries 1.
- Treatment: The treatment of MINOCA depends on the underlying cause and may include medications such as calcium channel blockers and nitrates for coronary vasospasm, as well as dual antiplatelet therapy (DAPT) in some cases 1.
Diagnostic approach to MINOCA
- Coronary angiography: To rule out obstructive coronary artery disease 1.
- Cardiac magnetic resonance (CMR) imaging: To identify the underlying cause of MINOCA and to assess for wall motion abnormalities, presence of edema, and myocardial scar/fibrosis 1.
- Additional diagnostic tests: Such as intracoronary imaging with IVUS or OCT, and pulmonary embolism testing, may be considered to exclude alternative diagnoses 1.
From the Research
Definition and Distinction
- Non-obstructive coronary artery disease (NOCA) refers to a condition where the coronary arteries are not significantly blocked, typically less than 50% stenosis 2.
- Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a specific type of myocardial infarction where the coronary arteries appear normal or near-normal on angiography, despite evidence of myocardial infarction 3, 4.
Pathophysiology
- MINOCA is a heterogeneous condition with various underlying pathophysiologic mechanisms, including epicardial vasospasm, coronary microvascular disorder, spontaneous coronary artery dissection, and coronary thrombus/embolism 2, 3.
- Non-coronary pathologies, such as Takotsubo cardiomyopathy and myocarditis, can also contribute to MINOCA 2, 3.
Diagnostic Approach
- A comprehensive diagnostic evaluation, including coronary imaging, cardiac magnetic resonance (CMR), and intracoronary imaging, is crucial for diagnosing MINOCA and identifying the underlying cause 3, 4.
- CMR is useful in making a definite diagnosis of MINOCA and excluding non-ischemic causes that mimic acute myocardial infarction (AMI) 3.
- Intracoronary imaging, such as optical coherence tomography (OCT), can help identify intracoronary morphological alterations, including plaque disruption and spontaneous coronary artery dissection 3, 4.
Clinical Implications
- MINOCA accounts for approximately 5-15% of acute myocardial infarctions and is associated with unique challenges for diagnosis and management 2, 5.
- The distinction between NOCA and MINOCA is essential, as MINOCA requires a tailored diagnostic and therapeutic approach to optimize treatment and improve prognosis 2, 3.