0:00

And this next video. I'd like to take a minute to talk about CAD rats.

0:04

What is CAD rats catarads is

0:07

one of these scoring systems that follows in

0:10

the tradition of other RADS types systems such as

0:13

bi-rads and Pirates. It's developed.

0:16

Of course by consensus of

0:19

multiple societies including

0:22

the American College of radiology American College

0:25

of Cardiology and some other societies

0:29

and basically it has been created to

0:32

develop a standardized method for reporting coronary

0:35

CT findings. It has been adopted by

0:38

many practices and it was originally published in 2016

0:41

and more recently updated just in 2022 up

0:44

to catarad's version 2.02 modification

0:48

added a couple things overall

0:51

plaque extent term called P1

0:54

through P4, which we'll talk about and then also an ischemia

0:57

modifier to reflect the development of we'll see

1:00

of fractional flow Reserve techniques that I'll talk

1:03

about as well. So just in general, you know,

1:06

should you use CAD RADS? I can't really answer that

1:09

question for you. I think it is helpful as

1:12

a standardized way of reporting and certainly if

1:15

you have multiple Radiologists reading that read things slightly

1:18

different way. It's a good way to achieve consistency across your

1:21

site. Do you have to use catarads? I

1:24

would say no.

1:25

there are some cardiologists out there who have worked

1:28

with who don't like catarads as much because of not

1:31

so much the disease categories, but rather the

1:34

recommendations for treatment that go with

1:37

them. Honestly, it probably comes down to a discussion with

1:40

you and your referring clinicians as to what what do you

1:43

think?

1:43

Is the best moving forward certainly?

1:46

Just using the catarads or a catarad's style.

1:49

Sort of reporting to lump patients into specific

1:52

categories is definitely useful for standardizing

1:55

the reporting across here your site

1:58

no matter how you do it.

2:00

So let's talk about the catarad score and basically

2:03

you're scoring the the patient 0 to

2:06

5. And this is the score based on the most severe stenosis

2:09

in the patient. So it's a per patient

2:12

score and the scores range from 0 no

2:15

disease.

2:16

One and two which are in the non obstructive minimal

2:19

and Mild disease categories. Then there's moderate disease

2:22

that gray area that we talked about in the last video on 50

2:25

to 69% stenosis.

2:27

And then severe disease which has two subheadings and

2:30

this is important. There's the 70% or

2:33

greater in one or two vessels which would be 4A or

2:36

4B which would be three vessels

2:39

70% or greater.

2:41

Or left main over 50% and why is

2:44

that a distinction that's made the main reason here is that patients

2:47

who are in the floor be category are actually

2:50

patients who may be best managed by

2:53

cabbage. And so those patients it may

2:56

be kind of a do not pass go situation where they need to go see the

2:59

surgeon and be evaluated or at least

3:02

get a cath to confirm these findings and then

3:05

be evaluated for potential surgery patients with

3:08

one to two severe stenoses the

3:11

management. There is a little Mercure

3:14

And it's really keeps evolving over time in the

3:17

past. I think the thought would have been that anybody with a severe

3:20

stenosis should really be evaluated for potential stenting and

3:23

revascularization. However, more recent

3:26

trials have shown that that may not be actually

3:29

needed in a lot of patience and medical therapy has

3:32

really shown to be just as successful in these

3:35

patients at least in improving mortality

3:38

and other nature cardiovascular outcomes

3:41

like a subsequent Mi heart attack

3:44

for instance and then cataracts five that's an inclusion

3:47

and non-diagnostic study.

3:50

So there are also other pieces to the cadread Schooler.

3:53

So you get a catarad score. Plus these other letters

3:56

that follow and the new one is

3:59

the plaque burden which is graded from

4:02

one to four one being mild to

4:05

being moderate three severe and for extensive they've actually

4:08

given us different ways to define the plaque

4:11

burden you can use a visual assessment. You can

4:14

do it from calcium score or you can

4:17

use this segmental involvement score. So the

4:20

calcium score you just look at the chart and whatever range your

4:23

calcium score falls into that's the number you give the patient P

4:26

1 through 4, so that's pretty simple.

4:29

The sis is the segmental involvement score. So

4:32

basically each coronary artery vessel segment

4:35

gets a score of 1 if they're involved with

4:38

any plaque of any kind. So a score

4:41

of three to four would mean that you may have the proximal and

4:44

mid LED and the proximal and mid-rca and

4:47

in that case you've got a score for

4:49

so it's actually doesn't take long to get you up to the severe level in

4:52

a lot of the patients that we see and then finally the

4:55

visual score they give you some information here about how to visually score

4:58

it. But basically it's a subjective assessment but

5:02

You know moderate amount would be one two vessels moderate out or

5:05

three with miles. So what is mild?

5:08

Meanwhile I'd say probably just one segment involved with vessel and

5:11

then it goes up from there.

5:13

What are the segments that we're talking about? Well, the coronary

5:16

artery segments have been defined by the Society of

5:19

cardiovascular CT and they have this guideline which

5:22

is widely available and they talk about the different segments

5:25

the corner arteries and basically you

5:28

have the left main is a segment approximal LED

5:31

is a segment middle. LED is a segment digital LEDs a

5:34

segment.

5:35

RCA proximal mid distal PDA,

5:38

you know, that's a segment the circumflex

5:41

proximal.

5:42

And then actually they lumped mid distal

5:45

into one segment for the circumflex and then each of

5:48

the major diagonal branches and obtuse marginal branches. And if you

5:51

have a ramus those are all segments as well. So basically, you know,

5:54

like I said, it doesn't take long to add up to quite a few segments with plaque When

5:57

you're counting up plaque severity.

5:59

Another thing that shows up in the cad

6:02

rats are these high-risk features and

6:05

Upstate? These are a bit controversial in terms

6:08

of it's not clearly known what to do with this high risk

6:11

plaque feature information and how it should affect management and that

6:14

that work is still being done. Some of this cadrad's information

6:17

is information that's going to be used to really

6:20

fuel future studies. That'll help us figure out how best

6:23

to use this information. But the idea behind these

6:26

high risk plaque features is that

6:28

There have been a lot of studies done where they take a look at patients who

6:31

end up having an acute coronary syndrome and

6:34

then they go back in time and look at what their coronary CT

6:37

was before they had this acute coronary syndrome. And when

6:40

you look at these patients, you'll find that these

6:43

particular features shown are more common in the

6:46

patients who end up going to acute coronary syndrome the problem

6:49

with the high risk plaque features. Unfortunately is that they're not very

6:52

specific you see these features and a lot

6:55

of patients and the vast majority of them will not go on to have acute coronary

6:58

syndrome. So that's where the question of how these will really

7:01

play into the patient management is still kind of a

7:04

little bit up in the air but hopefully more to come so as

7:07

we go through the different cases of

7:10

this course, I'm going to point out these features as we come across them.

7:13

But here's a review of the four features that are included

7:16

in the catarads.

7:18

So first, it's called spotty calcification and the idea

7:21

here is that you have a non calcified plaque, which

7:24

is this kind of lens shaped thing here and then within that

7:27

non calcified plaque, you've got a DOT of calcium in the

7:30

middle. That's spotty calcification.

7:33

Positive remodeling we talked about that already in the last

7:36

video. That's when the diameter of your vessel is

7:39

larger than the nearest normal segment because

7:42

the vessel has expanded to accommodate the plaque. And the

7:45

number here we think about is 1.1 a ratio of

7:48

1.1 of the level of the plaque compared to the normal

7:51

segment the napkin ring sign. This is honestly,

7:54

I think probably one of the tougher ones to see this and the low

7:57

attenuation plaque. This is actually when you look at a plaque

8:00

You see that you've got a low attenuation sort of

8:03

core of the plaque. Here's the Lumen. So

8:06

you've got this big non calcified plaque here. There's a low

8:09

attenuation area and surrounding that low attenuation area is

8:12

a brighter area, which is thought to be

8:15

an area of kind of enhancement of the rim of this plaque called

8:18

the napkin ring sign.

8:21

And then finally low attenuation plaque. That's a little more simple. That's where you get

8:24

non-calify plaque actually measures less than 30 ounce foot units these

8:27

two I would say are much more

8:30

rare to find. You know, when your day-to-day coronary

8:33

CT reading, whereas the top two, I'd say

8:36

are quite common when you're reading coronary c teams.

8:39

Other modifiers that are mentioned Within part of the catarad system

8:42

are listed here and you really would have

8:45

to refer to the whole cadres document to get all the

8:48

details. But basically there's also an addition

8:51

to non-diagnostic and high-risk black features we have ischemia

8:54

and that's to serve a yes/no stents. So

8:57

if you have a stent then you want to

9:00

you know mention that

9:01

Graft, let's say you have cabbage crafts.

9:04

Then your score should reflect the

9:07

patency of the graphed and the downstream

9:10

vessel beyond the graph the nestenosis your

9:13

score ignores any disease in the

9:16

native vessel, that's Upstream to the graph. So for instance, let's say

9:19

you have a LED occlusion. That's then

9:22

bypassed. You're not going to score the patient as a

9:25

you know, catarads five total occlusion. You're

9:28

gonna score them instead based on the patency

9:31

of the graph itself.

9:33

And then e is any sort of important coronary

9:36

findings that are not related to atherosclerosis such

9:39

as dissection aneurysmasculitis or something else along

9:42

those lines.

9:43

Just a quick note about ischemia and fractional

9:46

flow Reserve so ffr is something

9:49

that's come on to the scene in the past several years and as

9:52

generate a lot of excitement and the

9:55

idea here is that you take the anatomic information

9:58

about the coronaries and you

10:01

basically have these fancy computers with

10:04

high level processing power that segment out

10:07

the coronaries and based on the shape of the coronaries themselves.

10:10

They can actually calculate using these

10:13

computational fluid Dynamic approaches the

10:16

estimated flow across

10:19

the vessel in the various locations based on

10:22

the anatomy.

10:24

And it turns out that this actually holds up really well compared to

10:27

the gold standard which is actually sticking it down a catheter

10:30

in the patient and measuring the flow. And why

10:33

do we care about the flow? Well, the main reason we

10:36

care about the flow is that

10:37

We're interested in.

10:39

Whether or not there's a drop in flow across

10:42

the stenosis and the way that's measured by the

10:45

gold standard is this thing called the fractional flow reserve and

10:48

basically it's a ratio of the flow before and after

10:51

this stenosis and it tells us whether or not

10:54

there's a pressure drop across the stenosis.

10:57

And the amount of pressure drop that's important is a

11:00

pressure drop of 25% or greater.

11:03

So if your ffr is 0.75 that

11:06

means that you've had a 25% pressure drop that means

11:09

that you have a significance stenosis.

11:11

If your pressure drop is less than that if

11:14

it's less than 20% and that's consider not obstructive and

11:17

then there's this gray Zone which is somewhere between 25

11:20

and 20% pressure drop which is

11:23

considered indeterminate. So right now there is

11:26

a FDA approved third party vendor, which can do

11:29

this for you the way they have set up their system is

11:32

that you'll send out your coronary CT to their lab for processing and

11:35

then they'll send you back. The information afterwards folks are using

11:38

this basically to assess patients with

11:41

moderate disease and try to determine whether that moderate

11:44

disease is functionally significant or not. And sometimes

11:47

it can be surprising a plaque that looks really

11:50

severe on coronary CT on ffr analysis

11:53

may not be quite as severe. So it helps

11:56

guide and management and actually helps even more with

11:59

selecting patients who may need to go on to cardiac catheterization

12:02

and intervention and avoiding interventions

12:05

that aren't needed on patients who actually have ffr

12:08

which isn't in the obstructive.

12:12

Okay, and then my last slide on catarads is

12:16

just about the practice guidelines themselves and management

12:19

considerations that they

12:22

have Incorporated. So.

12:23

This is information within cataracts

12:26

says okay, if you have a catarads of you know, four what do

12:29

you do with the patient and it's a very busy slide

12:32

but basically the main thing you do and all these categories based

12:35

on some of the recent trial data is risk

12:38

factor modification and preventive pharmacotherapy. So

12:41

Optical medical management is in general recommended for

12:44

all these cases. Now, if you get into more severe

12:47

disease, you can consider catheterization and

12:51

revascularization if the symptoms persist after directed care

12:55

which in this case is usually medical management.

12:57

That's for those modern disease patients.

13:01

And then for those patients with severe disease.

13:03

Again, you want to do Optical medical management

13:06

and then consider other therapies

13:09

and revascularization per guidelines and the

13:12

guidelines, which is down here.

13:14

Would suggest that you could do some additional

13:17

Imaging or invasive coronary angiography.

13:20

If they're persistent symptoms, despite adequate medical

13:23

therapy. So a lot of this is getting back to

13:26

the fact that you know more recent trials have shown that

13:29

If you have a patient who has severe stenosis

13:32

that patient may not necessarily need to have

13:35

those stenosis opened up and revascularized that

13:38

Optical medical therapy can be just as effective

13:41

in a lot of those patients.

13:43

The one exception to that would be if patients have

13:46

severe Angel symptoms.

13:49

And that they don't improve with medical therapy. Then it is

13:52

recommended to go ahead and open up the stenosis and

13:55

revasclass those patients. So this is all within

13:58

the cataracts document and so it certainly

14:01

not expected that you remember any of this but just something to know

14:04

of as the next steps and what cadrads recommends

14:07

for our patients if we're using this

14:10

That sums up our cadrad's evaluation and

14:13

the next cases. We're going to move on to some real patient cases.