Contents
Signs & Symptoms
Patients with CAD can present with stable angina pectoris, unstable angina pectoris, or an MI. They may seek medical attention with their first symptomatic episode of chest discomfort. Many of these patients suffer from unrecognized CAD and may experience an acute plaque rupture or acute myocardial infarction as their first coronary artery diagnostic presentation. Electrical instability can ensue, including potentially lethal cardiac dysrhythmias.
Identifying high-risk persons before their first myocardial event is a multifaceted process that involves both patient- and physician-education efforts. Screening for coronary artery disease is not sufficient. Risk-factor modification, from an early age, initiates primary prevention efforts, forestalling the development of symptomatic CAD. Severe CAD can be detected before a patient develops symptoms, especially in a high-risk patient subpopulation in which pre-test probability of flow-limiting coronary artery disease is higher than average.
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Angina pectoris is a perceived symptom resulting from a mismatch of myocardial supply and demand. The compromised myocardial blood flow caused by obstructive CAD is not able to meet the metabolic and, specifically, the oxygen demands of the myocardial tissue. The anaerobic threshold is crossed and the patient develops symptomatic angina pectoris. Angina pectoris is typically categorized according to the Canadian Cardiovascular Society’s functional classification system (Table 1). Unfortunately, not all patients present with typical angina pectoris symptoms. In approximately 30% to 40% of patients, myocardial ischemia will present in an atypical manner that may consist of subtle symptomatology; discomfort isolated to the arm, throat, or jaw not readily recognized by the patient as a cardiac symptom; or with exertional fatigue, “heartburn”, or shortness of breath, not equated with a cardiac cause. Many patients have no symptoms at all and those that do often find it difficult to recollect and describe the exact symptoms, provoking factors, and duration.
Table 1: Canadian Cardiovascular Society Functional Classification of Angina Pectoris
| Class | Definition | Specific Activity Scale |
|---|---|---|
| I | Ordinary physical activity (e.g., walking and climbing stairs) does not cause angina; angina occurs with strenuous, rapid, or prolonged exertion at work or recreation. | Ability to ski, play basketball, jog at 5 mph, or shovel snow without angina |
| II | Slight limitation of ordinary activity. Angina occurs on walking or climbing stairs rapidly, walking uphill, walking or stair climbing after meals, in cold, in wind, or under emotional stress, or only during the few hours after awakening, when walking more than two blocks on level ground, or when climbing more than one flight of stairs at a normal pace and in normal conditions. | Ability to garden, rake, roller skate, walk at 4 mph on level ground, have sexual intercourse without stopping |
| III | Marked limitation of ordinary physical activity. Angina occurs on walking one to two blocks on level ground or climbing one flight of stairs at a normal pace in normal conditions. | Ability to shower or dress without stopping, walk 2.5 mph, bowl, make a bed, play golf |
| IV | Inability to perform any physical activity without discomfort. Anginal symptoms may be present at rest. | Inability to perform activities requiring 2 or fewer metabolic equivalents without angina |
Adapted from Goldman L, Hashimoto B, Cook EF, Loscalzo A: Comparative reproducibility and validity of systems for assessing cardiovascular functional class: Advantages of a new specific activity scale. Circulation 1981;64:1227-1234. |
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Stable Angina
Angina pectoris is said to be stable when its pattern of frequency, intensity, ease of provocation, or duration does not change over a period of several weeks. Identification of activities that provoke angina and the amount of sublingual nitroglycerin required to relieve symptoms are helpful indicators of stability versus progression. A decrease in exercise tolerance or an increase in the need for nitroglycerin suggests that the angina is progressing in severity or transitioning to an accelerating pattern.
Accelerating Angina
Angina pectoris is said to be accelerating when there is a change in the pattern of stable angina. This may include a greater ease of provocation, more prolonged episodes, and episodes of greater severity, requiring a longer recovery period or more frequent use of sublingual nitroglycerin. This suggests a transition and most likely reflects a change in coronary artery blood flow and perfusion of the myocardium. This frequently portends unstable angina or an acute coronary syndrome such as an acute MI. Should a patient transition from a stable to accelerating pattern of angina, acute medical attention is warranted.
Unstable Angina
Unstable angina pectoris occurs when the pattern of chest discomfort changes abruptly. Signs of unstable angina are: symptoms at rest, a marked increase in the frequency of attacks, discomfort that occurs with minimal activity, and new-onset angina of incapacitating severity. Unstable angina usually is related to the rupture of an atherosclerotic plaque and the abrupt narrowing or occlusion of a coronary artery, representing a medical emergency with an incipient acute coronary syndrome and an MI to follow. Immediate medical attention is mandatory.
