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First I'm going to talk about indications for coronary CT.

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first some background information about coronary CT

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the main strength of coronary CT is that it is a high

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negative predictive value. So it's really good at ruling out

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coronary artery disease.

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There's strong randomized control trial data supporting the

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use of Corners UT in both the outpatient and the Ed

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settings and there are multiple named trials

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with long acronyms that are out there that have basically over

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the years established a really strong

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base for using coronary CT in patients

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with acute chest pain showing up

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in the emergency room or in patients with

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chronic chest pain showing up to their outpatient cardiologist or

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family care physician in those emergency room

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settings. Coronary CT results in earlier discharge

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of patients from the emergency room compared to the traditional management.

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Traditionally patients would be admitted for a rule

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out mi or maybe they'd have a step-down unit in

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the Ed for a lot Mi that often would occur overnight

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and now those patients instead of having these overnight

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rule out protocols. They get to be sent home

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after a negative. Coronary CT.

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And then in the outpatient setting the use

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of coronary CT has resulted in less patients

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with unnecessary coronary angiography. And what

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does that mean? That means that when you're using other

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modalities to evaluate people with potential coronary

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art disease in particular we're talking about

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stress testing with either treadmill stress testing

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or maybe expect

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those modalities have a higher likelihood of false positive.

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And those patients who get a false positive study will

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then be referred to catheter angiography and

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then they'll find that they actually, you know don't have any significant

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disease so that if the study

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was a little bit better on the front end the patient could have avoided the

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test entirely and that's what we see with coronary CT that

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if you use coronary CT is a way to rule out

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significant disease, then patients won't go to

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coronary angiography and have negative results.

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And this is really nicely shown by some slide

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here that is from the guidelines

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that are actually recently published

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in 2021 for management of patients with chest pain

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by multiple societies including the

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American Heart Association the American College of Cardiology. And this

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is a really interesting slide from from those guidelines that

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shows you a graphical representation of all the

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different causes of chest pain in the Ed based on

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age and the important thing here is that the majority of patients

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in the Ed showing up with chest pain

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do not have coronary artery disease and in particular

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if you're less than 44 years old, we don't even see coronary

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art of disease show up on this graph. It didn't even meet the top,

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you know ten causes whereas if

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you get older in age and certainly coronary atherosclerosis is

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there but it's way way dwarfed in

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terms of prevalence by these non-specific chest

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pain causes that we may not actually ever find the

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reason for this patient's chest pain.

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So this is why the use of

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coronary CT and the idea is really helpful. You can screen these patients

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here this big blue category of patients and

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basically rule them out for any significant coronary disease

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and then send them on their way.

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So some other background information. What is the weakness of

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coronary CT? Well, although it's really good for ruling out

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disease when you have known disease and so people have really extensive

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coronary art disease people have had stents in

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the past things like that. It's less accurate at stratifying the lesion

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severity in those patients. So we're trying to differentiate between maybe a

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modest stenosis versus a severe stenosis which

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are you know terms that will get to later in the course. The coronary

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CT is a little less effective there and a lot

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of it has to do with calcification severe calcification

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on coronary CT causes blooming artifacts which

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limits the evaluation of stenosis.

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So in general the general concept is that

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corner? CT is optimally used as a rule out test for

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significant coronary artery disease in patients with either intermediate

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or low probability of coronary disease and chest

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pain and and patients in particular who may have

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other symptoms that could be related to ischemia like dismayon exertion

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or a new arrhythmia fatigue, you know Nuance at

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afib something like that where you want to make sure they this isn't

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because of some lurking cornea or disease but

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rather that you can you know, basically rule that

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out and treat the patient more conservative. So that's

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really where coronary CT fits in the management of patients

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with chest pain.

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Okay. So now I want to get back to those guidelines that

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I mentioned. So just recently the guidelines were

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updated in 2021 for the

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management of patients with chest pain and and what we saw

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was that these guidelines actually showed very

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strong support for the use of coronary CT as

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a modality for managing this patients and among

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the different Imaging modalities. Echo spect

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pet MRI different stress tests Corner

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CT actually had the highest strength of recommendation, and

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that's based on all those randomized control trials that

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I mentioned that have provided a lot of strong evidence back in

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coronary CT.

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So here are these guidelines this is the title as

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you can see lots of acronyms there because there

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are lots of different societies involved and this came

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out in 2021 and broke down management of

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patients with chest pain into a few different Pathways patients with

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acute chest pain and suspected acute coronary syndrome. So

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we think they may be having a heart attack IE patients

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in the Ed setting. So that's one group and then there's a patients with

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stable chest pain. Those are patients people. You're gonna see in

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the outpatient setting maybe they'll have chest pain or some sort

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of equivalent such as Disney on exertion or an arrhythmia

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or something fatigue. There are those patients who

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have no known coronary arteries in those patients with known corner

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or disease and if you go to these guidelines, they

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break down different algorithms for management of all these patients. The

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important thing here is that in patients with low or

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intermediate probability of disease and in particularly

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that intermediate group coronary CT to play

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as an important role. So here's a nice figure taken

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from this guidelines, which kind of

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Summarizes of the concepts here. Where does

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coronary CT fit in so basically, they broke

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down patients into the risk categories. And

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and how do you determine these risks? Well these online risk calculators

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that you can use and they base it on the patient's age

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and their sex and their lipid profiles

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and any other risk factors.

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Like are they a smoker for instance? And then

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from that you can figure out the risk category

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at those patients belong in and then

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Within These risk categories, you can figure

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out how to next best handle the patient if patients are

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either asymptomatic or low risk, then generally they're recommending no

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testing in the acute setting in Ed if

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they're an outpatient setting you might consider something

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like a screening test such as calcium scoring.

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Intermediate and low risk groups that makes up the largest population

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here here they say either anatomic or

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functional testing. So what's that mean that means either coronary CT

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that would be anatomic or something

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like a stress test looking for a schema. That would be functional.

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And the same thing is recommended here in this

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stable chest pain evaluation as well and then patients at

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high risk. So those are the patients who are coming in with a heart attack.

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They have an abnormal EKG. They have troponians. They're

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you know elevated. So those patients, you know, they're having

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a heart attack. You don't want to mess around and send them to anatomic or

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functional testing. They should be going directly to invasive coronary

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and geography so that they could be treated

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with a stent as needed. This is just the general

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overview.

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This is another figure from that same guideline which really helps

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put into context where CT fits in the management

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of these patients. Again, if you have a low pretest

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likelihood of coronary arteries, they they prefer no

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testing intermediate likelihood and

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a young patient. They favor coronary

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artery disease intermediate to

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high probability and older patient more likely

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to have coronary disease. So then you may favor stress

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testing again because in patients with a

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lot of disease coronary CT is a little less effective at

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stratifying the patients and this is

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a nice little table here talking about when

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coronary CT fits versus stress testing and

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in general if it's a rule out situation you want

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to rule out disease that favor is coronary CT a

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younger patient favors coronary CT

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or prior functional meaning prior stress

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testing income exclusive favors. Coronary CT as

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well as if you want to look at the pulmonary arteries or anomalies.

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Just to round it out. What about other coronary

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CT indications Beyond just chest pain certainly we

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can assess cabbage graphs. So this

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would again actually be somebody probably with chest pain

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or some sort of chest pain equivalent, but who has known disease and has had

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a cabbage coronary CT can be effective for that. We're

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not going to talk about that in this course that's going to be in a

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follow-up course on known corner or disease.

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Suspected coronary anomalies and young patient can genital

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heart disease and then of course non coronary

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cardiac evaluations such as structural heart disease, those are

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patients with aortic valves stenosis or mitral valve

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disease expected to get a valve replacement cardiac masses

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and then valve energy as well. Say for instance to

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look for a vegetation or pair of ovular abscessities and

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patient with bad valves.

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So that rounds out our coronary artery disease

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introduction. And so hopefully that helps give you

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a sense of when coronary CT fits into the

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management of patients.