Reaction of patients with effort angina to cold exposure during exercise

An attempt has been made to characterize so-called "responders" to cold among patients with effort angina. Forty-nine such patients, unselected with regard to their history of reactions to cold, who showed ST depressions during and after exercise, were examined. They worked on a bicycle ergometer close to their maximum capacity, Wmax, at room temperature (about 23 degrees C) and in a cold room (-15 degrees C). ECG was recorded and a rating scale was used to estimate the perceived exertion during exercise (RPE). The presence of angina pectoris during exercise and its duration after exercise was recorded by an EA score. An EA/W index was used to estimate the severity of the effort angina. In the whole group, the mean Wmax decreased and the mean ST depressions, RPE, and EA/W index (but not EA score) increased on exposure to cold. The changes in these variables due to exposure to cold were all associated (but not the EA score). Criteria requiring a decrease in Wmax or increase in ST depression, RPE or EA/W index on cold exposure identified 53 to 63 percent of the patients. By combining the criteria, the number of patients, who were identified, decreased. If all the criteria were applied, about 30 percent of the patients were identified as "responders" to cold and they showed the most marked responses. Thus several exercise ECG test parameters may be used to reliably define "responders" to cold exposure. This may enhance future studies of the response reaction.