From the Guidelines
Management of Non-Obstructive Coronary Artery disease (NOCA) and Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA) involves a comprehensive approach. The primary goal is to identify the underlying cause of MINOCA, which can be categorized into four main groups: epicardial coronary artery disorders, imbalance between oxygen supply and demand, coronary endothelial dysfunction, and myocardial disorders without involvement of the coronary arteries 1.
Diagnostic Criteria
The diagnosis of MINOCA is made based on the following criteria:
- Detection of a rise or fall in cardiac troponin with at least one value above the 99th percentile upper reference limit
- Corroborative clinical evidence of infarction, such as symptoms of myocardial ischemia, new ischemic electrocardiographic changes, or imaging evidence of new loss of viable myocardium
- Non-obstructive coronary arteries on angiography, defined as the absence of obstructive disease on angiography (i.e., no coronary artery stenosis >50%) in any major epicardial vessel
- No specific alternate diagnosis for the clinical presentation 1
Management Strategies
The management of MINOCA involves a step-wise approach:
- Initial Assessment: Proper initial assessment of LV wall motion should be promptly performed in the acute setting using LV angiography or echocardiography
- Cardiac Magnetic Resonance (CMR): CMR is a key diagnostic tool in the differential diagnosis of Takotsubo syndrome, myocarditis, or true MI, and can identify the underlying cause in as many as 87% of patients with MINOCA
- Medical Therapy: Medical therapy based on coronary functional test results should be considered to improve symptoms and quality of life, including:
- ACE-I for symptom control in patients with endothelial dysfunction
- Beta-blockers for symptom control in patients with microvascular angina associated with reduced coronary/myocardial blood flow reserve
- Calcium channel blockers and nitrates for symptom control in patients with vasospastic angina
- Intracoronary Imaging: Intracoronary imaging with IVUS or OCT may be valuable for the detection of unrecognized causes at coronary angiography, especially when thrombus, plaque rupture or erosion, or SCAD are suspected
Treatment Considerations
Treatment should target the most probable causes of MINOCA, with negative provocative tests and CMR. The benefit of DAPT (aspirin + P2Y12 receptor inhibitor) should be considered based on pathophysiological considerations, although evidence is scarce 1.
In patients with ANOCA/INOCA, medical therapy based on coronary functional test results should be considered to improve symptoms and quality of life, including the use of nitrates, calcium channel blockers, and beta-blockers 1.
Overall, the management of NOCA and MINOCA requires a comprehensive and individualized approach, taking into account the underlying cause and pathophysiological mechanisms involved.
From the Research
Management of Non-Obstructive Coronary Artery Disease (NOCA) and Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA)
- The management of MINOCA involves identifying the underlying cause of the condition to achieve patient-specific treatment 2, 3, 4, 5, 6.
- Clinical history, electrocardiogram, echocardiography, and coronary angiography are the first-level diagnostic investigations for MINOCA 2.
- Additional diagnostic tests such as coronary imaging with intravascular ultrasound and optical coherent tomography, coronary physiology testing, and cardiac magnetic resonance imaging may be necessary to understand the underlying cause of MINOCA 2, 3, 4, 5, 6.
- The prognosis of MINOCA patients depends on the underlying etiology and is not always benign 2, 6.
- Therapeutic management of MINOCA is limited due to the lack of evidence-based literature and prospective randomized controlled studies, and the strategy is patient-specific 6.
Diagnostic Approaches
- Coronary imaging with intravascular ultrasound and optical coherent tomography can help identify pathological alterations of the epicardial vessels that are not visible by coronary angiography 3.
- Cardiac magnetic resonance imaging is the gold standard for detection of myocardial infarction in the setting of MINOCA 4.
- Optical coherence tomography (OCT), intravenous ultrasound (IVUS), and cardiac MRI may be required to stratify the underlying mechanism of MINOCA 6.
Underlying Causes of MINOCA
- Epicardial causes of MINOCA include rupture or fissuring of unstable nonobstructive atherosclerotic plaque, coronary artery spasm, spontaneous coronary dissection, and cardioembolism in-situ 2.
- Microvascular causes of MINOCA include coronary microvascular dysfunction and supply-demand mismatch 2, 5.
- Other possible causes of MINOCA include Takotsubo syndrome and type-2 AMI due to supply-demand mismatch 2, 5.