These testing options are performed with the patient at rest.
Resting Electrocardiography
The most widely used cardiovascular diagnostic test, the routine resting 12-lead electrocardiography (ECG) is inexpensive but very useful. It can be easily performed in the physician-office setting and can indicate whether symptoms are being caused by cardiac conditions. ECG plots voltage variations in the heart over time and records the waveforms (Figure 6).
Figure 6. Basic ECG Waveforms and Intervals
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Non-Stress Testing
Stress Testing
Exercise vs. Pharmacologic Stress
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ECG can demonstrate evidence of infarction, ischemia, hypertrophy, arrhythmias, and conduction disturbances. Even some nondiagnostic ECG findings, such as mild or nonspecific ST-T wave changes, can help clinicians by suggesting a higher probability of a nondiagnostic stress ECG and the need for stress imaging.61
Resting ECG is generally not performed in asymptomatic patients. A normal resting ECG in asymptomatic patients cannot rule out CAD, so risk-assessment procedures are important for these patients.
Chest X-ray
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| A chest x-ray is often performed in patients with cardiopulmonary symptoms. X-rays can show cardiac enlargement, ventricular aneurysm, aortic abnormalities, pericardial effusion, or evidence of heart failure, which may support a diagnosis of CAD and help to assess the extent of cardiopulmonary involvement. |
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| Electron-Beam Computed Tomography
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Electron-beam computed tomography (EBCT) is a sensitive technique for detecting and measuring coronary artery calcification (CAC) as well as for detecting preclinical CAD. Measuring CAC with EBCT can help to further risk-stratify intermediate-risk patients,62 for whom the optimal management approach is often unclear.52
The majority of acute myocardial infarctions (MIs) are triggered by coronary lesions causing <50% stenosis.62 Therefore, measuring CAC can provide important risk-stratification information, which can be used to guide patient management. Determining a patient's CAC score with EBCT adds independent predictive value to traditional risk assessment.62 EBCT can also be used to track a patient's CAC score over time to evaluate the effectiveness of risk-reduction and treatment strategies.
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| Computed Tomographic Angiography
Computed tomographic angiography (CTA) is a relatively new procedure for detecting CAD that is far less invasive than traditional angiography, which requires the placement of a sizable catheter into a large vein or artery. The utility of CTA for CAD diagnosis continues to be studied, but results so far indicate that it will likely play an increasing role.
Studies of CTA for detecting >50% coronary obstruction have shown a sensitivity of 82% to 100% and a specificity of 78% to 98%.63 Its main strength appears to be its strong negative predictive value, which has been shown in recent studies to be 95% to 97% in patients at intermediate to high risk for CAD.63 It has also demonstrated utility for ruling out CAD in patients at low to intermediate risk and for evaluating patients with a prior coronary artery bypass graft who are scheduled for additional revascularization procedures.63
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