Myocardial infarction with nonobstructive coronary arteries (MINOCA) refers to the presence of an acute myocardial infarction (AMI), in absence of obstructive coronary artery disease (≥50% stenosis), and no overt cause for the clinical presentation at the time of angiography.
MINOCA occurs three times more in women than in men and also disproportionately affects Black, Hispanic, and Pacific persons.
Acute coronary syndromes constitute a variety of myocardial injury presentations that include a subset of patients presenting with myocardial infarction with non-obstructive coronary arteries (MINOCA).
Underlying mechanisms include coronary causes such as coronary spasm, coronary microvascular dysfunction, plaque disruption, spontaneous coronary thrombosis/emboli, and coronary dissection, endothelial dysfunction: myocardial disorders, including myocarditis, takotsubo cardiomyopathy, and other cardiomyopathies; and noncardiac causes, such as pulmonary embolism.
Acute coronary syndrome differs from type 1 myocardial infarction (MI) regarding patient characteristics, presentation, physiopathology, management, treatment, and prognosis.
MINOCA patients are younger, are more often female and tend to have fewer cardiovascular risk factors.
MINOCA occurs in up to 15% of patients with MI: accounts for overall 5 to 6% of patients with MI.
MINOCA affects 5-10% of acute myocardial infarction patients who have minimal to no discernible high-grade critical coronary arterial stenosis.
Prevalence is dependent on the definition used, and it ranges between 1and 15%, with an overall prevalence of 6% in a meta-analysis.
Women have an almost 5 times higher incidence of MINOCA than men.
Majority of patients are older women with significant atherosclerosis risk factors including: diabetes, hypertension, and hyperlipidemia.
Appropriate therapy remains unclear.
Patients with MINOCA frequently have manifestations of atherosclerotic disease and other areas, such as peripheral vascular disease.
SWEDEHEART study revealed approximately 6% of patients with MINOCA subsequently suffer a second myocardial infarction, and angiography at that time reveals that half of the patients had developed clinically important coronary arterial stenosis.
In the above study 22% of patients who developed a re-infarction die during a 2.3 year follow-up and a half of the deaths were cardiovascular.
Approximately 14% die during a 4.5 year follow up.
In the absence of coronary artery disease, myocardial ischemia might be triggered by an acute event in epicardial coronary arteries, coronary microcirculation, or both.
Two-thirds of MINOCA subjects present ST-segment elevation.
Long-term outlook of such patients remains controversial.
Some report a more favorable prognosis compared with patients with myocardial infarction and obstructive coronary artery disease.
Others report MINOCA in-hospital and 1-year mortality rates of 0.9% and 4.7%, respectively.
Patients with MINOCA have a higher adjusted risk of mortality at one year compared with patients with non–ST elevation myocardial infarction and coronary artery disease (5.2 versus 1.6%).
Personality traits are not likely to be associated with MINOCA.
Mortality associated with current events is substantial, although there is no difference in mortality between those with or without significant coronary artery disease.
Patients with MINOCA should not be regarded as having a benign condition, patients should receive the same management as patients with myocardial infarction due to coronary artery disease (Pellicia F).
Cardiac magnetic resonance imaging (CMRI) has the ability to detect common causes of MINOCA.
CMRI may identify the underlying cause in as many as 87% of patients with MINOCA.
Epicardial causes of MINOCA include coronary plaque disruption, coronary dissection, and coronary spasm.
Microvascular MINOCA mechanisms involve microvascular coronary spasm, Takotsubo syndrome (TTS), myocarditis, and coronary thromboembolism.
Coronary angiography with non-significant coronary stenosis and left ventriculography are first-line testing.
Echocardiography can help indicate vasospasm or thrombosis.
Prognosis of these patients, report a 12-month all-cause mortality of 4.7%, with comparative studies consistently demonstrating a better prognosis than for those who experience AMI associated with obstructive coronary artery disease.
12-month major adverse cardiac events are comparable to patients with AMI associated with single- or double-vessel coronary artery disease.
25% of patients with MINOCA continue to experience angina 12 months after AMI, which is equivalent to the rate in those with AMI associated with obstructive coronary artery disease.
Elevated troponin levels are related to the extent of myocardial involvement and blood flow.
Optical CT plus cardiac MRI (CMR) provides a more specific diagnosis in the majority of women presenting with myocardial infarction with nonobstructive coronary arteries (MINOCA): identifying the underlying cause of MINOCA in 85% of women.
With these techniques overall, 64% of women with MINOCA had a true MI and 21% had an alternate nonischemic diagnosis, most commonly myocarditis.
OCT identified a definite or probable culprit lesion in 46% of women, most commonly atherosclerosis or thrombosis.
A culprit lesion is associated with older age, abnormal angiography findings at the site, and diabetes, but not peak troponin level or severity of angiographic stenosis.
Optical CT/ cardiac MRI shows evidence of infarction or regional injury in 69%.
When the OCT and CMR results were combined, a cause of MINOCA was identified in 84.5% of women.
Three-fourths of the causes were ischemic (64% MI) and one-quarter were nonischemic with 15% myocarditis, 3% Takotsubo syndrome, and 3% nonischemic cardiomyopathy.
In the remaining 15%, no cause of MINOCA was identified.
Noninvasive CMR appears helpful in the diagnosis of nearly three-quarters of these patients and perhaps could be done first to direct which of those with an ischemic cause might benefit from invasive OCT at catheterization.
Analysis approach to examine the effect of 4 conventional postinfarct therapies-statins, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, β-blockers, and dual antiplatelet therapy: a reduced hazard ratio of major cardiovascular events for statins, and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers.
In patients with angina and no obstructive coronary artery disease treated with placebo or diltiazem resulted in no benefit in reduction in symptoms of angina.