Summary
Cardiac stress testing is an umbrella term for diagnostic studies that evaluate cardiac function using ECG or cardiac imaging while stress is induced in the heart. Imaging modalities include echocardiography, myocardial perfusion imaging (MPI), and cardiac MRI (CMR). Cardiac stress testing is most commonly used to assess for stress-induced cardiac ischemia. Stress is induced by increasing heart rate and contractility (using exercise or dobutamine) or inducing a coronary steal phenomenon (using vasodilators such as adenosine, dipyridamole, or regadenoson), which leads to increased myocardial oxygen demand, facilitating the detection of myocardial ischemia.
Overview
General principles
- Myocardial stress can be induced through exercise or pharmacological substances.
- Choice of testing modality depends on the indication and patient factors (including ability to exercise and contraindications). [1]
- Beta blockers, CCBs, and nitrates can affect stress test results and may be held before testing. [2]
- End testing when: [2][3][4]
- Diagnostic endpoint is reached (e.g., findings suggestive of stress-induced ischemia) [5][6]
- Target heart rate threshold is achieved (if no diagnostic endpoint is reached)
- Significant cardiac arrhythmia
- Any indications for early test termination are present (see “Exercise stress testing” and “Pharmacological stress testing” for respective indications)
Exercise stress testing is generally preferred for evaluating stress-induced ischemia. [3][7]
Common uses [2][6][8]
- Evaluation for myocardial ischemia in selected patients, e.g.:
- Stable angina or anginal equivalents: most useful for risk stratification in patients with an intermediate to high pretest probability of obstructive CAD [7]
- Cardiomyopathy or heart failure of unclear etiology
- CAD risk assessment after cardiac revascularization
- Valvular heart disease: to determine exercise capacity [9]
- Selected cardiac arrhythmias: e.g., for treatment evaluation
Cardiac stress testing is most commonly used to assess for stress-induced ischemia.
Monitoring during examination [5]
-
Heart rate
- Target heart rate: 85% of the maximum heart rate
- Estimated maximum heart rate = 220 - age (in years)
- Blood pressure
- 12-lead ECG
Exercise stress testing
Modalities [2][6][10][11]
- Exercise ECG testing
- Exercise stress imaging
Contraindications [2][3]
- Inability to exercise
- Recent unstable angina or acute MI (within the past 2 days)
- Uncontrolled symptomatic and/or hemodynamically significant arrhythmias
- Symptomatic severe aortic stenosis
- Acute cardiac conditions, e.g.:
- Active endocarditis
- Acute aortic dissection
- Acute myocarditis or pericarditis
- Decompensated heart failure
-
Relative contraindications include:
- Other cardiovascular conditions: e.g., tachyarrhythmias, AV block, recent stroke or TIA
- Circulation-relevant conditions: e.g., significant anemia, electrolyte imbalances
- Modality-specific restrictions (e.g., contraindications to MRI)
Procedure [2][6]
- Follow the standard or modified Bruce protocol. [6]
- Induce stress using a treadmill or bicycle.
- Quantify exercise intensity using metabolic equivalents.
- Adjust exercise intensity to achieve the target heart rate (85% of maximum heart rate).
- Continue the protocol until the diagnostic endpoint is reached or there is an indication for early termination.
Indications for early termination [3]
- Cyanosis, pallor, ataxia, dizziness, or near-syncope
- Severe dyspnea
- Moderate to severe angina
- Decrease in systolic BP > 10 mm Hg below resting BP with other signs of ischemia
- Relative indications
- Symptoms: increasing chest pain, fatigue, wheezing, leg cramps, claudication
-
Vital signs
- Decrease in systolic BP ≥ 10 mm Hg below resting BP without other signs of ischemia
- Exaggerated hypertensive response, i.e., systolic BP > 250 mm Hg or diastolic BP > 115 mm Hg
- Heart rate > 85% of age-predicted maximum
-
ECG
- Excessive downsloping ST depression or horizontal ST depression of > 0.2 mV (2 mm)
- Arrhythmias with the potential to become hemodynamically significant
- Bundle branch block (if unable to distinguish from ventricular tachycardia)
Interpretation
See “Diagnosis of coronary artery disease” for findings suggesting CAD.
Pharmacological stress testing
Modalities [1][8]
ECG monitoring is typically used in addition to cardiac imaging.
Contraindications [1][4]
-
General restrictions
- Systolic BP > 200 mm Hg or diastolic BP > 110 mm Hg
- Acute MI within the past 2–4 days, unstable angina, acute coronary syndrome
- Substance-specific contraindications: See “Procedure” below.
- Modality-specific contraindications (e.g., contraindications to MRI)
Procedure [1][8]
Stress is induced by substances that simulate the effect of exercise on the myocardium.
Positive inotropes or chronotropes
- Agent: dobutamine
- Mechanism: increases heart rate and contractility
-
Contraindications
- Obstructive cardiomyopathy
- Aortic dissection
- Tachyarrhythmias
Vasodilators
- Agents: dipyridamole, adenosine, or regadenoson
- Mechanism: induces a coronary steal phenomenon
-
Contraindications
- Active bronchospasm, reactive airway disease, or history of severe reactive airway disease
- Systolic BP < 90 mm Hg
- Adenosine or regadenoson stress tests: second-degree AV block, third-degree AV block, or sinus node disease in patients without a pacemaker
-
Preparation
- Hold methylxanthines (e.g., caffeine, aminophylline) for 12 hours before testing.
- Before adenosine or regadenoson stress tests: Hold dipyridamole for 48 hours.
Indications for early termination [4]
- Wheezing, cyanosis, pallor
- Systolic BP < 80 mm Hg
- Chest pain with excessive downsloping ST depression or horizontal ST depression of > 0.2 mV (2 mm)
- Symptomatic second-degree AV block or third-degree AV block
- For dobutamine only:
- Exaggerated hypertensive response
- Systolic BP > 230 mm Hg
- OR diastolic BP > 115 mm Hg
- Heart rate > 85% of age-predicted maximum
- Exaggerated hypertensive response
Interpretation
See “Diagnosis of coronary artery disease” for findings suggesting CAD.
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