Physical examination
Palpation and auscultation of the chest may detect the presence of a friction rub or significant murmur, and thus identify a nonischemic cause for the chest symptoms. Carotid bruits or reduced pedal pulses indicate the presence of other vascular diseases. Patients with xanthomas, hypertension, or signs of congestive heart failure are more likely to have CHD, while those whose pain can be reproduced by body movement or by palpating the chest are less likely to have CHD.
Risk factor assessment. The assessment of risk factors for CHD allows the identification of many patients at high risk for CHD and can be helpful in guiding the choice of additional tests. As evident in the Framingham Heart Study,4 independent risk factors such as cigarette smoking, hypertension, diabetes mellitus, and hyperlipidemia are direct causes of CHD.
Laboratory tests
In the patient at low risk of CHD, blood testing for cardiac markers is not indicated. A lipid profile and blood glucose level help to establish the risk level associated with hyperlipidemia and diabetes. A complete blood count (eg, for anemia), thyroid hormone studies (eg, for hyperthyroidism), arterial blood gases (eg, PCO2 for chronic obstructive pulmonary disease), and other tests may help in diagnosing contributory conditions.
Resting electrocardiogram
A routine resting 12-lead ECG is an inexpensive but critical test that can provide important diagnostic and prognostic information. Evidence of infarction, ischemia, hypertrophy arrhythmias, and conduction disturbances can be detected and, if present, substantially increase the likelihood of a cardiac cause of symptoms.
Even the presence of mild or nonspecific ST-T wave changes, while not diagnostic, can aid the clinician by suggesting a higher probability of a nondiagnostic stress ECG and the need for an imaging stress test.3 An abnormal resting ECG with ST-T wave changes associated with digoxin use, left bundle branch block, left ventricular hypertrophy, and so on, limit interpretation of an exercise ECG, and points to a need for exercise testing with imaging.
It is important to note that a normal ECG obtained when the patient is asymptomatic does not exclude CHD, and additional risk stratification with noninvasive diagnostic stress testing may be indicated.5
Chest x-ray
A chest x-ray is often appropriate for patients with cardiac or pulmonary signs/symptoms. It may show cardiac enlargement, ventricular aneurysm, or evidence of heart failure, which may support the diagnosis of CHD and help to assess the extent of cardiopulmonary involvement.
Noninvasive stress testing
Considering our 2 patients with occasional episodes of unexplained chest discomfort: Based on the ECG and clinical findings, their risk for CHD is considered low to intermediate.
Test selection
Diagnostic tests should be selected based on the clinician’s estimate of probability of CHD.2
Low probability. If the likelihood of CHD is low, stress testing is generally not indicated, as its specificity is extremely low, and test results do not improve diagnostic accuracy over the clinical impression alone.
Intermediate probability. If the patient is able to exercise to capacity, the choice is exercise testing. Patients who can exercise and have an interpretable ECG, with no evidence of left ventricular dysfunction and no prior revascularization procedure, should usually undergo standard stress ECG testing. If the ECG is not interpretable, (due to repolarization abnormalities, left bundle branch block, left ventricular hypertrophy, digoxin use, etc) an exercise test with imaging (nuclear or echocardiographic) is indicated.
For patients unable to exercise, pharmacologic stress testing with imaging is indicated.
High probability. If the probability of CHD is high, it is reasonable to proceed directly to coronary angiography.
Exercise stress test
Exercise testing is a cardiovascular stress that uses treadmill or bicycle exercise with ECG and blood pressure monitoring. Such testing is widely available and relatively inexpensive.2 It allows assessment of exercise capacity and correlation of symptoms with ECG changes typical of myocardial ischemia.
Exercise testing provides the highest level of incremental diagnostic and prognostic information for patients with an intermediate probability of CHD.2 An important objective of stress testing is to identify individuals with a high risk for severe (left main or 3-vessel) CHD. More invasive procedures, such as percutaneous cutaneous angioplasty (PCTA), are recommended for these high-risk individuals to improve their survival.
Candidates for exercise treadmill testing include patients with stable symptoms who can be expected to exercise to an adequate workload. Patients with repolarization abnormalities on the resting ECG, such as left bundle branch block, left ventricular hypertrophy, or digoxin use, frequently have noninterpretable stress ECGs and may benefit from imaging techniques.
Limitations. Some patients referred for exercise treadmill testing are unable to achieve either adequate exercise levels or the target heart rate due to comorbid conditions,6 such as degenerative joint disease, obesity, pulmonary disease, peripheral vascular disease, central nervous system disorders, physical deconditioning, chronotropic incompetence, and medications such as beta blockers. More subtle factors, such as an unwillingness to exercise, may also affect a patient’s suitability for stress testing. These patients should be considered for pharmacologic stress testing.