Coronary artery disease: Clinical sciences

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Introduction0:00–0:41

Coronary artery disease, or CAD, is caused by atherosclerosis of the coronary arteries, which occurs when plaque builds up in the vessels, eventually narrowing the lumen, and causing a mismatch between oxygen supply and demand of the heart.
Over time, reduced oxygen supply can lead to myocardial ischemia or even infarction. The diagnosis of CAD is based on atherosclerotic risk factors that categorize patients into low, intermediate, or high risk groups based on their probability for obstructive disease.
Now, if you suspect CAD, first perform an ABCDE assessment. This is to determine if the patient is unstable or stable.

Unstable patient0:41–3:28

If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access, provide supplemental oxygen, and put them on continuous vital sign monitoring including blood pressure, heart rate, and pulse oximetry.
At this point, you should suspect CAD with acute coronary syndrome, which includes unstable angina, non-ST elevated myocardial infarction, or NSTEMI, or ST-elevated myocardial infarction, or STEMI.
Once you stabilize the patient, obtain a focused history and physical examination, and order serial troponin levels and an ECG.Okay, let’s focus on unstable angina, your patient may report sudden chest discomfort that doesn’t improve with rest, and feelings of uneasiness or “impending doom”.
Other common symptoms include dizziness, shortness of breath, sweating, as well as nausea. Physical exam typically reveals a distressed, anxious, and diaphoretic individual.
Ok, next take a look at the serial troponins. If there’s no myocardial infarction, troponins will typically be normal.
While ECG may or may not show signs of ischemia like ST segment depression or new T wave inversion. This combination of history, physical exam, labs, and ECG findings are characteristic of unstable angina, where chest pain is caused by an insufficient supply of oxygen to the cardiac tissue.
In these individuals, treatment consists of Morphine, Oxygen, Nitrates, and Aspirin, also known as MONA, as well as a statin and a beta blocker.
Additionally, your patient will likely need an invasive coronary angiography with or without revascularization. Here’s a clinical pearl!
A non-ST elevated myocardial infarction, or NSTEMI, can present with similar history, physical exam, and ECG findings as unstable angina, but troponin levels are typically elevated in NSTEMI by definition.
However, troponins may initially not be detectable, and may even take hours to rise after presentation, so be sure to keep NSTEMI on your differential even if troponin is normal.
Okay, let’s return to the ABCDE assessment and take a look at stable patients. If your patient is stable, obtain a focused history and physical exam.

Stable patient3:28–6:06

Your patient will typically describe their chest discomfort or pain as a heavy pressure that is worse with exertion, cold weather, or highly stressful situations, and improves when these conditions subside.
Your patient might also report shortness of breath with exertion.They may also have ASCVD risk factors, such as increasing age, male sex, hypertension, diabetes mellitus, hyperlipidemia, tobacco use, and a family history of premature CAD.
Okay, moving on to the physical exam, you may find elevated blood pressure, decreased peripheral pulses, and bruits, which are all evidence of atherosclerotic disease.
You may also see xanthelasmas, or yellow cholesterol deposits on the eyelids, which indicate underlying hyperlipidemia. Finally, you might detect nicotine-stained fingertips in patients that use tobacco.
These findings should make you suspect CAD, particularly stable angina. Now, here’s a high-yield fact!
The key thing that distinguishes stable from unstable angina is that pain improves with rest in stable angina, while pain remains present even at rest with unstable angina.
You should also keep in mind that if your patient is a biologically female individual, has a positive history of diabetes mellitus, and reports back or epigastric burning or stabbing pain, you should think of atypical angina!Now that you suspect CAD, your next step is to order labs.
These include a high-sensitivity troponin, fasting lipid panel, and hemoglobin A1C. Also, you should obtain a 12-lead ECG.
Labs typically reveal troponin levels as normal, lipid panel will reveal an elevated LDL, and hemoglobin A1C elevated too, which is common in patients with poorly controlled diabetes.
On the flip side, ECG could be normal, or show inverted T waves, which is a repolarization abnormality; pathological Q waves, indicating an old myocardial infarction; or a left bundle branch block.All these findings are highly suggestive of CAD causing stable angina, so your next step is to assess the pretest probability of obstructive CAD.

CAD6:06–6:37

You can do this by using the patient’s age, sex, chest pain symptoms, and risk factors. This allows you to stratify the patient into a low, intermediate, or high risk group and determine the appropriate type of management.Okay, lets first look at individuals who are at low risk.

Low risk for obstructive disease6:37–7:58

Patients who are low risk likely have non-obstructive CAD and do not require additional testing. Instead, you should encourage lifestyle modifications, such as a diet rich in fruits, vegetables, whole grains, and fish, as well as 150 minutes of moderate exercise each week, often divided up as 30 minutes 5 times a week, and sleep hygiene.
Counsel your patient on tobacco cessation and weight loss, annual influenza vaccines, and mental health. Next, start your patient on daily antiplatelet therapy, with aspirin or clopidogrel.
Additionally address their underlying risk factors and comorbidities by optimizing therapy for hyperlipidemia, hypertension, and diabetes mellitus.
Finally, schedule regular follow ups every three months to reevaluate the patient’s condition.Here’s a clinical pearl! Non-obstructive CAD, sometimes called functional CAD, is typically associated with coronary vasospasm.
Meanwhile, obstructive CAD, sometimes called structural CAD, is characterized by gradual narrowing of the coronary arteries, typically from atherosclerosis.Now, let’s switch our focus to intermediate-risk individuals, who require additional testing to determine the best treatment plan.

Intermediate risk for obstructive disease7:58–9:55

First, order a stress test based on your assessment of the patient’s ability to exercise. If they are able to exercise, assess their baseline ECG findings.
If normal, proceed with an exercise stress test, like use of a treadmill, with ECG. However, if the baseline ECG is abnormal, you’ll need an exercise stress test, like with use of a treadmill, but this time with echocardiogram or nuclear imaging to look for ischemic changes.
On the flip side, if your patient can’t exercise, then order a pharmacologic stress test with imaging instead. Use medications like adenosine, dipyridamole, or dobutamine to stress the heart, and imaging methods, like echocardiogram or nuclear imaging, to look for signs of ischemia.
Alright, once done, assess the stress test results. Assessing the stress test results will allow you to confirm the severity of the ischemia.No ischemia and mild ischemia confirm the diagnosis of non-obstructive CAD.
In these patients, treatment consists of counseling on lifestyle modifications, daily antiplatelet therapy, and optimizing the treatment of their risk factors and comorbidities.
Additionally, if stable angina is present, treat with nitrates and beta blockers, as well as ranolazine if needed. Finally, don’t forget to do regular follow-ups every one to three months.On the flip side, if the stress test reveals moderate to severe ischemia, then your patient has obstructive CAD, and will need invasive coronary angiography with or without revascularization.
They will also require the same treatment as non-obstructive disease after their procedure.Lastly, let's go back and discuss a high risk individual.

High risk for obstructive disease9:55–10:42

This suggests obstructive CAD. These patients will need invasive coronary angiography with or without revascularization.
Additionally, they will require the same treatment as non-obstructive disease after their procedure.Here’s a clinical pearl!
Patients who fail revascularization, or who have severe obstruction involving left main or multivessel coronary artery diseases, may need a coronary artery bypass graft, or CABG, where coronary grafts are used to direct blood around artery stenoses and obstructions.
A CABG is often used as a last or emergent operation as it is a major surgical procedure. Alright, as a quick recap….If you suspect CAD, first do an ABCDE assessment to determine if your patient is unstable or stable.

Review10:42–12:35

If unstable, stabilize their airway, breathing, and circulation. Once stabilized, obtain a focused history and physical, and order labs and ECG, which will help you diagnose CAD with acute coronary syndrome.
In these individuals, start MONA therapy, a statin, and a beta blocker. Your patient will likely need invasive coronary angiography with or without revascularization.
On the other hand, in stable individuals with CAD, first determine the risk of obstructive CAD based on atherosclerotic risk factors.
Low risk patients likely have non-obstructive disease so they don’t require additional testing. The treatment primarily relies on lifestyle modifications, antiplatelet therapy, and addresses underlying risk factors and comorbidities.
For intermediate risk patients, obtain a stress test based on their ability to exercise. Next, assess test results for signs of ischemia.
If the stress test shows no or mild ischemia, then treat with the same non-obstructive CAD management but don’t forget to manage angina, if present, with nitrates, beta blockers, or ranolazine.
However, if the test reveals moderate or severe ischemia, your patient has obstructive CAD and will need invasive coronary angiography and revascularization.
And finally, high risk patients likely have obstructive CAD and will also need invasive coronary angiography and