I was reminded today that with all of the discussion about cardiac MRI, many folks may get the wrong idea about the test and when it is useful.

Let's do a mini thread on this!

Cardiac MRI (CMR) is an excellent and cost effective test when used appropriately. It can be among the lowest cost cardiac imaging tests and it delivers high quality images with very good record of accuracy and safety.

So what are some of the indications (applications) of CMR in medicine?

Assessment of the size and function of the cardiac chambers.

CMR is the most accurate test for chamber enlargement and reduced squeeze function.

These may prompt important changes in medical therapy.

Assessment of viability. After a heart attack, doctors may want to know how much muscle is alive or dead to decide if its worthwhile to do a procedure to improve blood flow like bypass surgery or a stent.

This is done w/ late gadolinium enhancement (LGE) imaging and works quite well to identify those who will have improve heart function after the procedure.

Whether this identifies people who will live longer with surgery is the subject of ongoing trials.

The scar imaging can also help doctors assess the risk of life threatening arrhythmia and to guide specialists in how to do ablations to reduce the risk of recurrent arrhythmias.

In patients with abnormal hearts due to reasons other than heart attacks, the pattern of scar can give hints as to the cause of the scarring.

We can also measure the amount of iron that has been deposited in the heart. This is critical in some genetic conditions and in people who repeatedly need many blood transfusions.

Without treatment, iron overload in the heart can be fatal. Good data from the UK suggests that after they started testing people at high risk, survival improved meaningfully.

There are other important indications too like stiffening of the sac the heart lives in (pericardial constriction) that can be very crippling.

There are even a few cases we may do CMR in people without any signs of symptoms of heart disease. The most important of these are when a person has a genetic variant that is associated with inherited heart disease (or a close relative has one of these conditions).

Overall, this is an important tool that can have a massive impact on the quality of life and even survival of cardiac patients.

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I want to thank @JoaoLCavalcante for suggesting I do this thread.