Patient Preferences and Clinical Guidelines

Angina pectoris is the cardinal symptom of ischemic heart disease, and there are several well-established methods to measure its severity. The number of attacks in a week or a month is the simplest measure of severity. The frequency of angina provides an incomplete picture, however, since patients with stable angina soon learn the level of effort that brings on discomfort. They can reduce their activity level sufficiently to avoid angina, rendering them symptom free, but impaired nevertheless.1The Canadian Cardiovascular Society classification assesses whether a specific level of ambulation, such as walking up a flight of stairs, precipitates angina.2The Canadian system and further refinements of its basic approach3,4define angina severity in terms of threshold of activity needed to cause symptoms—the less strenuous the activity needed to precipitate angina, the more severe the symptoms. See also p 1185. Severity of angina can be assessed simply by