An assessment of the exercise capacity of cardiac patients.

T HE rehabilitation of the patient with heart disease must include placing him in appropriate employment. Gainful work serves not only economic ends but has important psychologic benefits. One of the important decisions the clinician must therefore make is an assessment of the level of effort that the patient can safely undertake in employment and sport. Traditionally the evaluation is made on subjective symptoms and physical signs. With reliance chiefly on the patient's statement of the grade of effort that produces breathlessness and discomfort the physician places him in one of the categories of functional capacity outlined by the New York Heart Association. The clinical assessment has obvious limitations. The main weakness is apparent when one attempts to relate the level of effort at which the patient claims that disability occurs to a physiologic measure of work, namely, liters of oxygen consumed per minute. Unless this is done it is virtually impossible to match precisely an evaluation of the patient's functional capacity with the grade of effort required to carry out various types of work or sport. Some attempts have been made in this direction by Nylin' and Bruce and Rodgers2 but the level of oxygen consumption at which disability occurs is not readily obtainable by their methods. The present studies are an endeavor to define precisely the maximum exercise capacities of cardiac patients in terms of liters of oxygen consumption per minute. The maximum capacity for effort of normal men can be defined as the maximum level of "aerobic" oxygen consumption. Astrand3 and