What is MINOCA?

What is MINOCA?

MINOCA is short form for myocardial infarction with non-obstructive coronary arteries. Myocardial infarction is heart muscle damage due to loss of blood supply, usually due to a block in the blood vessel to the region. Coronary arteries are blood vessels of the heart. But in MINOCA, though there is heart muscle damage, there is no significant block in the blood vessel to that region as seen on imaging tests like coronary angiogram. Coronary angiogram is X-ray imaging of the blood vessels of the heart obtained during injection of radiocontrast medications into them. In short, MINOCA is a heart attack without a block!

Up to 6% of all heart attacks can come under the group of MINOCA. They are more likely in younger individuals and females, but less likely to have high blood levels of fat. Other risk factors are similar to that of a usual heart attack. One year mortality of MINOCA is lower than that of a heart attack associated with a block in the blood vessel. In about a quarter of those with MINOCA, the blood vessels to the heart could be shown to contract on its own in response to certain medications. Increased clotting tendency of blood was noted in about one seventh of the cases.

For diagnosing MINOCA, there should be evidence of heart muscle damage by blood tests, imaging tests and symptoms suggestive of heart attack. The main feature is absence of more than 50% narrowing in the blood vessels of the heart, which is taken as the cutoff for significant narrowing. There should not be features of other types of heart disease like stress cardiomyopathy (heart muscle damage due to extreme stress, typically loss of spouse in an elderly female, also known as broken heart syndrome).

In a large study of around 200, 000 heart attack admissions in Sweden, nearly 9500 had MINOCA. Some of the important medications given for secondary prevention after a heart attack showed long term benefits, while some others had minimal or no effect in those with MINOCA.