Exercise Stress ECG is the Most Appropriate Next Step
For this 60-year-old man with exertional chest pain, normal resting ECG, and normal cardiac enzymes, an exercise stress ECG is the most appropriate initial diagnostic test. 1
Rationale for Exercise Stress ECG
This patient meets all the key criteria that make exercise stress ECG the optimal first-line test:
- Normal resting ECG - No ST-segment abnormalities, bundle branch blocks, or other confounding findings that would make ECG interpretation unreliable 1
- Ability to exercise - The patient has osteoarthritis of only one knee, which should not prevent achieving ≥5 METs of exercise capacity 1
- Stable symptoms - Exertional chest pain relieved by rest suggests stable angina rather than acute coronary syndrome 1
- Normal cardiac enzymes - Rules out acute myocardial injury, making this an intermediate-risk stable chest pain presentation 1
Guideline Support
The 2021 AHA/ACC Chest Pain Guidelines provide Class 2a, Level B-R recommendation that "for intermediate-high risk patients with stable chest pain and no known CAD with an interpretable ECG and ability to achieve maximal levels of exercise (≥5 METs), exercise electrocardiography is reasonable." 1
The AHA specifically states that "exercise ECG testing should be used in most chest pain centers as the first-line noninvasive stress test for ambulatory patients when the resting ECG is normal and the patient is not on digoxin therapy." 1
Why Not the Other Options?
Echocardiogram
- Resting echocardiography is indicated when there are pathological Q waves, signs of heart failure, complex arrhythmias, or heart murmurs - none of which are present in this case 1
- Would not provide functional assessment of exercise-induced ischemia 2
CT Coronary Angiography
- While CCTA is effective for intermediate-high risk patients, it is preferentially recommended for those <65 years of age not on optimal preventive therapies 1
- Exercise stress testing is favored in those ≥65 years (this patient is 60) with higher likelihood of ischemia 1
- More expensive as initial strategy without proven superiority in this clinical scenario 3
Dobutamine Stress Echocardiography
- Pharmacologic stress testing is reserved for patients unable to exercise adequately 1
- The 2021 guidelines list "inability to achieve ≥5 METs or unsafe to exercise" as a contraindication to exercise ECG, necessitating stress imaging 1
- This patient's single knee osteoarthritis should not prevent adequate exercise 2
Clinical Advantages of Exercise ECG in This Case
- High negative predictive value - In low-to-intermediate risk populations, negative exercise ECG effectively excludes significant CAD 1
- Cost-effective - Exercise ECG is significantly less expensive than imaging modalities while providing excellent diagnostic and prognostic information 3, 4
- Functional capacity assessment - Provides objective measurement of exercise tolerance and hemodynamic response 1, 5
- Safety - Symptom-limited maximum testing has very low incidence of adverse events 1
- Excellent outcomes - Community studies show 5-year mortality of 1.2% and combined event rate of 3.8% in similar populations managed with exercise ECG 4
Important Caveats
If the exercise ECG is inconclusive (fails to achieve 6 METs or 85% age-predicted maximum heart rate without ischemic changes), the patient should undergo further evaluation with stress imaging 1
If the exercise ECG is positive or equivocal, CCTA or stress imaging would be reasonable next steps 1
The osteoarthritis should be assessed to ensure it won't limit exercise capacity below the diagnostic threshold - if significant functional limitation exists, then dobutamine stress echocardiography would become the appropriate choice 1, 2