Myocardial infarction with non obstructive coronary arteries (MINOCA)  had a prevalence of 6% among myocardial infarctions noted in a recent systematic review . They are more likely to be younger and female, but less often have dyslipidemia as a risk factor. Other risk factors were found to be similar. Total mortality at one year with MINOCA is about 4.7% compared to 6.7% with myocardial infarction associated with obstructive coronary artery disease. Typical myocardial infarction as demonstrated by cardiac magnetic resonance imaging (CMR) was noted only in about one fourth of cases. One third had myocarditis while about one fourth cases had no significant abnormality on CMR. Inducible coronary spasm occurred in a about one fourth of cases and thrombophila was noted in 14%.
For diagnosing MINOCA, criteria as per the universal definition of myocardial infarction should be satisfied along with absence of significant coronary stenosis (50% or more). There should be no overt cause for the clinical presentation like takotsubo cardiomyopathy .
A recent observational study  of MINOCA took patients from the SWEDEHEART registry (the Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapy) . Of 199 162 myocardial infarction admissions screened, they found 9466 patients with MINOCA. They evaluated the 9136 patients who survived 30 days after discharge in order to assess the role of medical therapy for secondary prevention. They found long term benefits with statins and angiotensin converting enzyme inhibitors / angiotensin receptor blockers. There was a trend towards positive effect with beta blockers, while dual antiplatelet therapy had a neutral effect.
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