Stress tests are stressing me out: which stress test to order, Part 1

Looking for a summary decision algorithm after you finish reading this post? Check out Part 2.

Who should get a stress test?

Stress tests assess:

  • New anginal symptoms
  • Whether medical therapy or revascularization worked in the setting of known angina
  • Identifying new defects after a heart attack.

Those with a moderate pretest probability of having coronary artery disease (CAD) should get a stress test–see below. If a person has a very low pretest probability, even a positive result probably wouldn’t impress you too much. If a person has a high pretest probability, even a negative result would not be reassuring that there were not new ischemic damage there.

screen-shot-2016-12-01-at-5-35-42-pm

How do you know if the stress test is adequate?
If they reach a heart rate of 220-age x85%, then it’s adequate.
If the rate pressure product > 20,000, then it’s adequate.

What are the different kinds of stress tests available?

Atif Qasim, UCSF
Atif Qasim, UCSF

Why choose an EKG stress test?
EKG stress tests are a great first choice for relatively healthy individuals who don’t have underlying EKG abnormalities. Symptoms during the test or changes in the EKG can indicate ischemic problems but can’t tell you where exactly the changes are happening.

Why choose an ECHO stress test?
If a patient has baseline EKG abnormalities, such as previous MI, heart block, etc. then an EKG stress test is obviously harder to interpret. This is when an ECHO comes in handy. ECHO is also good for those with known CAD. They can also show wall motion abnormalities and identify specific areas that aren’t pumping as well, and give an ejection fraction.

Why choose a pharmacological stress test? 
These stress tests use adenosine, dobutamine, or persantine. They are good for patients who physically cannot exercise.

Which pharmacological agent should I choose?
In reality, the cardiac techs will choose the appropriate agent, but you should still know indications to specific agents. Vasodilators are contraindicated in bronchospasm, high-grade AV block, or severe hypotension. Do not give dobutamine if the patient has active CHF, hypertrophy, or atrial fibrillation.
Do not give persantine if the patient has history of bronchospasm and is on bronchodilators, COPD, sick sinus syndrome, or severe CAD.

Why choose a nuclear stress test?
Nuclear stress tests are useful in figuring out where an exact perfusion defect is. But do NOT use a nuclear test in women who could be pregnant or people with three-vessel disease (the contrast won’t help you as much).

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