0:01

Indications for coronary CT.

0:02

So, um, firstly, I'm talking about

0:04

coronary CT, not cardiac as a whole genre.

0:09

So this is a subset of cardiac CT.

0:14

It's important because it's a controversial topic.

0:17

And it's also important because

0:18

it's an expanding topic.

0:20

I, amongst many others, believe that this is

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something that should be, and most likely will

0:26

be, in the province of the general radiologist,

0:29

just like a PE study, just like a, um, dissection

0:32

study, uh, appendicitis study, which is very common.

0:36

And the reason it's very common is

0:38

because of the first indication.

0:39

The first indication is low

0:42

risk acute coronary syndrome.

0:43

So what do I mean by that?

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I mean patients who come to the emergency

0:47

department with a very low chance of actually

0:50

having something wrong with their coronary

0:53

artery as a cause of their chest pain.

0:55

Thank you.

0:57

Remember, we're not doing this to find MI,

1:00

so it's not as if, oh, so the patient has

1:03

elevated troponins and abnormal ECG, like ST

1:09

elevation, and let's find out if the patient

1:12

has a blockage before we take them to the cath lab.

1:14

That's not why we're doing this at all.

1:16

And if that's the indication,

1:17

then that's a wrong indication.

1:19

So in those with a high pretest

1:21

probability, we're not doing this.

1:23

We're doing this in those with a low, very

1:26

low pretest probability in order to tell them

1:29

whether the patient has coronary narrowing that

1:32

could be so much that it may be responsible for

1:37

the patient's chest pain, that they may have

1:40

an acute coronary syndrome, maybe unstable

1:44

angina, therefore they may need to be admitted.

1:47

Uh, the test is more powerful when it's negative than

1:49

when it's positive, because when it's negative you're

1:51

giving them a kind of a warranty, okay, it's not that.

1:54

When it's positive, it may still not be that.

1:58

But low risk acute coronary syndrome, and

2:00

we'll talk more about variations of the theme

2:03

on that, but that's essentially the most

2:05

important indication for radiologists to

2:08

get involved with in the ED.

2:12

The second indication is

2:14

an emerging indication, which is stable

2:17

coronary artery disease, stable CAD.

2:19

So these are people that don't just suddenly wake

2:21

up one morning saying, "Oh no, I have chest pain."

2:24

They've developed chest pain

2:25

over a long period of time.

2:27

They may be on medication for it.

2:29

Now the question is, do they need to go to

2:32

the cath lab to see if they have narrowing

2:35

that needs a stent or needs a bypass.

2:40

In the past, and even now, the tests used for those

2:44

patients were functional tests such as an exercise

2:48

ECG, nuclear medicine test, or a stress echo, and what

2:54

you look at in those tests is whether, when you stress the

2:58

heart, there is a wall motion abnormality

3:03

or an ECG abnormality or a perfusion defect.

3:06

Um, what we're doing with the

3:07

coronary CTA is quite the opposite.

3:10

What we're saying is, is there narrowing

3:13

enough for there to be a problem with the

3:16

patient's coronary artery that could potentially

3:19

benefit from a stent or from a bypass?

3:24

It's controversial, not because

3:27

narrowings don't exist.

3:29

It's controversial because you may not

3:31

need to stent them or bypass them; you

3:33

might just need to give them medication.

3:36

In which case, well, what's the point of actually

3:40

finding out whether they have narrowing or not?

3:42

But we can leave the controversies aside and

3:45

understand that that is a major indication

3:47

for stable coronary artery disease.

3:49

There are three others, which are sort of related.

3:55

One is a preoperative assessment.

3:57

So people that go for aortic

3:59

stenosis, mitral valve repair,

4:03

and other heart diseases, cardiologists have

4:08

traditionally wanted to clear the coronary arteries

4:10

because these are very stressful procedures.

4:13

And if there is anything brewing one may

4:17

not have known about, then the stress of the

4:19

procedure can cause a heart attack or a stroke.

4:22

So it's important to get an idea if there is

4:27

something that needs to be done concurrently.

4:29

So preoperative assessment of the coronary

4:30

arteries, uh, used to be done with a cath,

4:33

but now you can do this quite easily.

4:34

So that's a big indication.

4:37

The other indication is heart failure.

4:38

Somebody who comes in, who's

4:40

young, comes in with heart failure.

4:42

Um, they could have heart failure from

4:45

abnormalities of their coronary arteries, or they

4:47

could have it from other causes, non-ischemic.

4:51

So coronary CTA is a good way of

4:53

actually excluding coronary artery

4:55

abnormality.

4:57

If the coronary arteries are clean, then it's

4:59

unlikely that it's from coronary artery disease,

5:02

and then they should pursue non-ischemic causes.

5:05

And finally, anomalous coronary arteries, so coronary

5:08

arteries that come off the wrong place, and I'll

5:10

show a couple of examples of that in the course.

5:13

These patients generally present with chest pain,

5:17

or they may even have syncope, and it's part of

5:19

the workup to rule out structural heart disease

5:25

predisposes the patient to sudden cardiac death

5:29

and anomalous coronary artery is one of those.