Professor John Beltrame, Professor of Medicine, The Queen Elizabeth Hospital, University of Adelaide, Australia

Professor John Beltrame speaks to Cardio Debate and Radcliffe Cardiology about MINOCA diagnosis and if this should prompt further investigation to find the underlying cause, during ESC 2015 in London, UK.

Transcript – What is MINOCA?

MINOCA stands for Myocardial Infarction with Non-Obstructive Coronary Arteries. So to fulfill the criteria for this condition you have to have the universal criteria for acute myocardial infarction, so that’s a troponin rise associated with clinical features of a myocardial infarction, as well as having evidence of non-obstructive coronary arteries on angiography – so that’s having no stenosis that are 50 per cent or more. And that’s the definition of MINOCA.

When is it important to diagnose this condition?

The condition is diagnosed shortly after angiography. So when a patient presents with what’s thought to be an acute myocardial infarction undergoes coronary angiography and no significant stenosis are recognized, that’s when the diagnosis is made.

So it’s not a diagnosis where these is a clear cause for the myocardial infarction with the raised troponin. For example, if you have a young patients who presents with a viral-like illness associated with pleuritic chest pain, the diagnosis of myocarditis is the likely cause and you are merely taking angiography to exclude significant coronary artery disease. Then that diagnosis should be myocarditis and not MINOCA.

Whereas the reason for establishing the diagnosis of MINOCA is where the cause is not quite clear, and it is to prompt the clinician for further investigation.

So for example, in some cases because there is no significant coronary artery disease some clinicians would suspect that perhaps the patient hasn’t had a myocardial infarction. However it is important to understand what the cause is.

So similar to heart failure, you can diagnose heart failure and then you have to diagnose the cause. You diagnose MINOCA and you have to find the underlying cause. And probably the most common cause is myocarditis, but there are certainly other causes that need to be considered.

So the first investigation that really should be considered is a cardiac MRI, because when you undertake a cardiac MRI it will give you the diagnosis of myocarditis, you can also see if there is a typical myocardial infarct on the MRI, and may also give you clues to other unusual causes such as a cardiomyopathy.

Why is MINOCA important?

It’s important because in contemporary cardiology the underlying is not identified. So one of the important causes coronary artery spasm, the cause of the myocardial infarction. So if that’s the case, and our research shows that somewhere between 20 to 25% of cases coronary artery spasm is responsible, this can be treated effectively with calcium channel blockers.

And so if a diagnosis of MINOCA is not made and therefore it prompts further investigation, such as looking for coronary artery spasm, then effective treatment may not be implemented.

Another causes to consider in about 10% of cases is that there may be an underlying thrombotic disorder, and so screening should be undertaken for that. But as we said the most common cause is myocarditis, and a cardiac MRI will help you identify that cause.

So again, the reason for making the diagnosis of myocarditis, is similar to heart failure, is to find the underlying cause of MINOCA.