Rapid Review·Cardiovascular
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HY Approach
T1Must knowApproach to Stress Testing
Focus on
Three questions choose the study: is the patient stable, can they exercise to target, and is the resting ECG interpretable? Then know what to hold before the test, which stress agent is wrong for asthma or critical aortic stenosis, what makes a result high-risk, and how to read a perfusion scan (a defect that appears only with stress is ischemia; a defect present at rest and stress is scar).
Key takeaways
When to order a stress test
The indication
stable chest pain with an intermediate pretest probability; low probability gets no test and high probability starts therapy (Approach to Chest Pain).The alternative
coronary computed tomography angiography (CCTA) is the non-invasive alternative at intermediate probability.- A positive result on either goes to invasive coronary angiography.
Choosing the test
Exercise stress test is first choice if the patient can exercise
usually an electrocardiogram (ECG) stress test; echocardiography or radionuclide perfusion imaging can be added.- The exercise ECG needs a normal baseline ECG to be readable.
Cannot exercise
a pharmacologic stress test, a vasodilator (dipyridamole, adenosine, regadenoson) or an inotrope (dobutamine), typically with imaging plus ECG.| Test | Mechanism | Best for and cautions |
|---|---|---|
| Exercise ECG | Raises myocardial oxygen demand | First line when the patient can exercise and the baseline ECG is normal |
| Vasodilator (adenosine, dipyridamole, regadenoson) | Dilates normal coronaries more than diseased ones: coronary steal | Cannot exercise; needs imaging; avoid with reactive airway disease or theophylline |
| Dobutamine stress echo | Raises demand through beta-1 stimulation | Cannot exercise and cannot take a vasodilator; avoid with tachyarrhythmia |
Preparation
Anti-ischemic drugs
hold beta blockers, calcium-channel blockers and nitrates before the test.Methylxanthines
hold caffeine and aminophylline for 12 hours before a vasodilator test.Dipyridamole
hold for 48 hours before an adenosine or regadenoson test.Reading the result
Positive or high-risk features
ST depression over 1 mm at a low workload, a fall in systolic blood pressure, poor exercise capacity, or a ventricular arrhythmia.- These go to invasive coronary angiography with a view to revascularization.
Myocardial perfusion imaging
a technetium-99m agent (sestamibi or tetrofosmin) diffuses passively into perfused myocardial cells.- Images are taken at rest and after stress and compared territory by territory, as in the Interpret the stress/rest images.
| Pattern | Meaning |
|---|---|
| Normal uptake at rest and stress | No ischemia |
| Fixed defect (reduced uptake at both rest and stress) | Likely scar |
| Reversible defect (reduced with stress, normal at rest) | Inducible ischemia |
A 60-year-old with atypical chest pain and severe knee arthritis cannot walk on a treadmill; he has asthma. Which stress test fits, and what does a defect at stress that normalizes at rest mean?
He cannot exercise, and asthma rules out a vasodilator, so dobutamine stress echocardiography. A defect at stress that is normal at rest is a reversible defect: inducible ischemia, which goes to coronary angiography.
How it's tested
Intermediate-probability chest pain, can walk, normal resting ECG: exercise ECG.
Same patient with a paced rhythm: vasodilator nuclear perfusion imaging.
A patient with severe chronic obstructive pulmonary disease and wheeze who cannot exercise: dobutamine stress echocardiography; adenosine would provoke bronchospasm.
During the treadmill test systolic pressure falls from 140 to 110 with 3 mm ST depression at 4 minutes: high-risk result; coronary angiography, not medical management alone.
The patient had two espressos before an adenosine scan: the test is invalid; caffeine blocks the vasodilator; reschedule after 12 hours caffeine-free.
Reduced anterior uptake at stress that normalizes at rest: reversible defect; inducible ischemia in the left anterior descending territory.
Reduced inferior uptake on both stress and rest images in a man with a prior inferior infarct: fixed defect; scar, not new ischemia.
Go deeper
Guidelines: 2021 AHA/ACC Chest Pain Guideline
Related Step 2 pages: Approach to Chest Pain, Stable Angina, Approach to Preoperative Cardiac Evaluation
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