A resting ECG should be obtained in all patients who complain of chest discomfort. In patients with chronic stable angina, the ECG is normal in one-third of patients and, if abnormal, most often shows nonspecific ST-T changes without evidence for myocardial infarction.
The presence of left bundle branch block in patients with angina is often associated with significant left ventricular dysfunction and may reflect multivessel CAD. The presence of Q waves is usually a specific but insensitive indicator of myocardial infarction. Ischemic ST-segment deviations (depressions or elevations) and/or T-wave inversions occur commonly in patients with unstable angina; these changes usually resolve with relief of pain.
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New persistent symmetric T-wave inversion in the anterior precordial leads is a marker for high-grade left anterior descending or left main artery disease, and it should be recognized that these patients are at increased risk for infarction. Persistence of ST and T-wave changes may also suggest a non-Q wave infarction.
There is a fairly close correlation between ischemic ECG lead abnormalities and the anatomic site of coronary obstruction. Ischemic changes in the inferior leads (II, III, aVF) indicate right coronary or circumflex artery disease. Abnormal changes in the anterior precordial leads suggest left anterior descending artery disease, and changes in the left lateral (V2-V4) or high lateral leads (I, aVL) imply either diagonal or circumflex artery disease.
What are the indications for cardiac catheterization in patients with angina?
Cardiac catheterization and coronary angiography should be performed if the diagnosis of CAD cannot be reliably made by noninvasive diagnostic tests. Whether all patients with unstable angina need catheterization is controversial. Clearly, those patients with unstable angina who carry high-risk clinical markers need coronary angiography. An argument can be made to assess those patients with low-risk clinical profiles and who respond quickly to medical therapy with a noninvasive test such as a stress thallium scan. Catheterization is indicated for patients with chronic stable angina who begin to break through or fail medical therapy. Patients under age 50 who present with angina may also benefit from coronary angiography, since some of these patients may have advanced multivessel CAD or significant coronary anomalies. Patient age, in itself, is not a contraindication to catheterization, but patients who are not candidates for either angioplasty or bypass grafting and who have another life-threatening illness usually do not need cardiac catherterization.
Dyslipidemias (total cholesterol 200 mg/dL, low density lipoprotein cholesterol 160 mg/dL, increased triglycerides, and high density lipoprotein cholesterol 35 mg/dL
Other more controversial risk factors include elevated apoprotein a, alcohol use, stress, hyperinsulinemia, elevated fibrinogen levels, left ventricular hypertrophy, type A personality behavior, angiotensin-converting enzyme (ACE) genotype, and cocaine use.