What are the indications for a graded (exercise) stress test?

Indications for Graded Exercise Stress Testing

Exercise stress testing is indicated for symptomatic patients with intermediate pretest probability of coronary artery disease (15-65%) who can exercise adequately and have an interpretable baseline ECG, as this provides both diagnostic and prognostic information at lower cost than imaging modalities. 1, 2

Primary Diagnostic Indications

Suspected Coronary Artery Disease

• Perform exercise ECG testing in patients presenting with angina-like chest pain who have intermediate pretest probability (15-65%) of CAD, can achieve adequate exercise (≥4-5 METs), and have a normal baseline ECG. 1, 2
• Exercise stress testing is most accurate when the resting ECG is normal and the patient is not taking digoxin. 3
• The test provides functional capacity assessment, blood pressure response, heart rate recovery, and ECG changes during physiologic stress. 1

Known Coronary Artery Disease

• Use exercise ECG testing in patients with established CAD on medical therapy to assess symptom control and presence of inducible ischemia. 2
• Exercise testing helps confirm that persistent chest pain despite optimal medical therapy is anginal and evaluates functional capacity. 2

Risk Stratification Indications

Preoperative Evaluation

• Perform stress testing in patients undergoing vascular surgery or nonemergent noncardiac surgery who have poor functional capacity (<4 METs) or active cardiac symptoms. 4, 5
• For organ transplantation candidates (kidney or liver), consider noninvasive stress testing in those with ≥3 risk factors: diabetes, prior CAD, >1 year on dialysis, left ventricular hypertrophy, age >60 years, smoking, hypertension, or dyslipidemia. 6

Asymptomatic Patients with Risk Factors

• Consider exercise stress testing in asymptomatic patients with multiple cardiac risk factors, as it provides valuable prognostic information. 7
• Men over 40-45 years or postmenopausal women over 50-55 years with at least one coronary risk factor should undergo testing before vigorous competitive activities. 2
• Asymptomatic men over 40 with at least one risk factor and two abnormal exercise features have a 30-fold increase in 5-year cardiac risk. 2

Diabetes-Specific Indications

• Perform graded exercise testing in diabetic patients who are age ≥35 years, have type 2 diabetes of ≥10 years duration, have type 1 diabetes of ≥15 years duration, or have any additional CAD risk factor before embarking on moderate-to-high intensity physical activity programs. 6
• Testing is also indicated in diabetic patients with microvascular disease (proliferative retinopathy or nephropathy), peripheral vascular disease, or autonomic neuropathy. 6

When to Choose Imaging Over Standard Exercise ECG

Baseline ECG Abnormalities

• Do not perform exercise ECG alone in patients with left bundle branch block, paced rhythm, Wolff-Parkinson-White pattern, left ventricular hypertrophy with strain, ≥0.1 mV ST-depression at rest, or chronic digitalis therapy—these require stress imaging instead. 1, 2
• These baseline abnormalities render the ECG non-interpretable for ischemia and produce high false-positive rates. 1, 2

High Pretest Probability or Reduced LV Function

• Select stress imaging (stress echo, SPECT, PET, or CMR) when pretest probability of CAD is high (66-85%) or when left ventricular ejection fraction is <50% in patients without typical angina. 2

Prior Revascularization

• Use imaging stress testing in symptomatic patients with prior PCI or CABG to evaluate for recurrent ischemia. 2

Inconclusive Exercise ECG

• Proceed to imaging stress testing when exercise ECG is inconclusive—patient fails to reach ≥85% age-predicted maximal heart rate without symptoms, or exercise is limited by orthopedic or other non-cardiac problems. 2

Special Population Considerations

Women

• Exercise ECG has lower sensitivity and specificity in women with more false-positive results compared to men. 2
• Nevertheless, for women who can exercise and have normal baseline ECG, exercise ECG without imaging remains the preferred initial test for risk stratification. 2
• Women achieving <5 METs on exercise are at higher risk and may benefit from pharmacological stress imaging. 2

Elderly Patients

• All patients over 65 years old, even without risk factors or symptoms, should undergo exercise testing. 2
• Because of comorbidities, pharmacologic stress testing may be necessary if adequate exercise cannot be achieved. 7

Absolute Contraindications

Do not perform exercise stress testing in patients with: 1

• Acute coronary syndrome
• Decompensated heart failure
• Severe symptomatic aortic stenosis
• Uncontrolled arrhythmias
• Acute aortic dissection
• Acute pericarditis or myocarditis
• Severe hypertension (≥200/110 mmHg)
• Acute pulmonary embolism

Key Prognostic Markers During Testing

High-risk findings that indicate severe CAD and poor prognosis include: 1, 2

• ST depression at low workload (<6 minutes on Bruce protocol)
• Failure to increase systolic blood pressure
• ST-segment elevation during exercise
• Complex ventricular ectopy
• Delayed heart rate recovery
• Exercise capacity <5 METs
• Chest pain during maximal exertion

Common Pitfalls to Avoid

• Do not rely solely on age-predicted heart rate formulas, as there is high variability among individuals of identical age. 4
• A negative test does not rule out coronary artery disease—it serves only as preliminary evaluation to estimate likelihood of CAD presence. 2
• Exercise stress testing is rarely appropriate for known CAD patients with no new symptoms <2 years after PCI or <5 years after CABG. 5