Essentials of Diagnosis

• Precordial chest pain, usually precipitated by stress or exertion, relieved rapidly by rest or nitrates.
• Electrocardiographic or scintigraphic evidence of ischemia during pain or stress testing.
• Angiographic demonstration of significant obstruction of major coronary vessels.

General Considerations
Angina pectoris is usually due to atherosclerotic heart disease. Coronary vasospasm may occur at the site of a lesion or, less frequently, in apparently normal vessels. Other unusual causes of coronary artery obstruction such as congenital anomalies, emboli, arteritis, or dissection may cause ischemia or infarction. Angina may also occur in the absence of coronary artery obstruction as a result of severe myocardial hypertrophy, severe aortic stenosis or regurgitation, or in response to increased metabolic demands, as in hyperthyroidism, marked anemia, or paroxysmal tachycardias with rapid ventricular rates. Rarely, angina occurs with angiographically normal coronary arteries and without other identifiable causes. This presentation has been labeled syndrome X and is most likely due to inadequate flow reserve in the resistance vessels (microvasculature). Although treatment is often not very successful in relieving symptoms, the prognosis of syndrome X is good.

Clinical Findings
A. History
The diagnosis of angina pectoris depends principally upon the history, which should specifically include the following information.

1. Circumstances that precipitate and relieve angina  - Angina occurs most commonly during activity and is relieved by resting. Exertion that involves straining the thoracic or upper extremity muscles (eg, lifting or walking rapidly uphill) precipitates attacks most consistently. Patients prefer to remain upright rather than lie down. The amount of activity required to produce angina may be relatively consistent under comparable physical and emotional circumstances or may vary from day to day. It is usually less after meals, during excitement, or on exposure to cold. The threshold for angina is often lower in the morning or after strong emotion; the latter can provoke attacks in the absence of exertion. In addition, discomfort may occur during sexual activity, at rest, or at night as a result of coronary spasm.

2. Characteristics of the discomfort  - Patients often do not refer to angina as “pain” but as a sensation of tightness, squeezing, burning, pressing, choking, aching, bursting, “gas,” indigestion, or an ill-characterized discomfort. It is often characterized by clenching a fist over the mid chest. The distress of angina is rarely sharply localized and is not spasmodic.

3. Location and radiation  - The distribution of the distress may vary widely in different patients but is usually the same for each patient unless unstable angina or myocardial infarction supervenes. In 80-90% of cases, the discomfort is felt behind or slightly to the left of the mid sternum. When it begins farther to the left or, uncommonly, on the right, it characteristically moves centrally substernally. Although angina may radiate to any dermatome from C8 to T4, it radiates most often to the left shoulder and upper arm, frequently moving down the inner volar aspect of the arm to the elbow, forearm, wrist, or fourth and fifth fingers. Radiation to the right shoulder and distally is less common, but the characteristics are the same. Occasionally, angina may be felt initially in the lower jaw, the back of the neck, the interscapular area, high in the left back, or in the volar aspect of the wrist. If the patient identifies the site of pain by pointing to the area of the apical impulse with one finger, angina is unlikely.

4. Duration of attacks  - Angina is of short duration and subsides completely without residual discomfort. If the attack is precipitated by exertion and the patient promptly stops to rest, it usually lasts less than 3 minutes. Attacks following a heavy meal or brought on by anger often last 15-20 minutes. Attacks lasting more than 30 minutes are unusual and suggest the development of unstable angina, myocardial infarction, or an alternative diagnosis.

5. Effect of nitroglycerin  - The diagnosis of angina pectoris is strongly supported if sublingual nitroglycerin invariably shortens an attack and if prophylactic nitrates permit greater exertion or prevent angina entirely.

6. Risk factors  - The presence of risk factors described previously makes the diagnosis of angina more likely, but their absence does not exclude angina since most patients do not have a risk profile markedly different from that of the general population.

B. Signs
Examination during a spontaneous or induced attack frequently reveals a significant elevation in systolic and diastolic blood pressure, although hypotension may also occur. Occasionally, a gallop rhythm and an apical systolic murmur due to transient mitral regurgitation from papillary muscle dysfunction are present during pain only. Supraventricular or ventricular arrhythmias may be present, either as the precipitating factor or as a result of ischemia.

It is important to detect signs of diseases that may contribute to or accompany atherosclerotic heart disease, eg, diabetes mellitus (retinopathy or neuropathy), xanthelasma, tendinous xanthomas, hypertension, thyrotoxicosis, myxedema, or peripheral vascular disease. Aortic stenosis or regurgitation, hypertrophic cardiomyopathy, and mitral valve prolapse should be sought, since they may produce angina or other forms of chest pain.