Angina in cold environment. Reactions to exercise.

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Abstract
Male patients [17] with angina pectoris and a history of increased severity of angina in the cold performed submaximal bicycle exercise tests in a normal (20.degree. C) and a cold environment (-10.degree. C, 2.2 m/s wind velocity) wearing standardized clothing. Observations were made during and after serial short-term exercise periods each starting at 50 W [work unit], with continuous load increase of 10-30 W per min separated by 30 min rest intervals. In the group as a whole maximal work load decreased by 7% during exposure to cold. Heart rate, systolic blood pressure and rate-pressure product were significantly higher during submaximal exercise in the cold, but at maximal work load there was no difference in heart rate, rate-pressure product or magnitude of ST segment depression. The decrease in maximal work load exceeded 5% (mean 11%) in 10 patients who were described as cold-susceptible; the decrease averaged 1% in 7 non-susceptible patients. The cold-induced reduction in maximal work load showed a significant correlation with the increase in heart rate, blood pressure and rate-pressure product during submaximal exercise. After exercise heart rate was significantly lower and blood pressure and rate-pressure product significantly higher in the cold than at normal temperature in all patients. In cold-susceptible patients blood pressure was significantly higher at 2 and 4 min after exercise, and rate-pressure product at 2 min after exercise, than in non-susceptible patients, but, in spite of this, angina disappeared more quickly in cold-susceptible patients. Subjective cold intolerance was objectively demonstrated in 10 of 17 patients with angina pectoris by exercise in a room at -10.degree. C. Susceptibility to cold was explained by a higher heart rate and blood pressure during exercise in the cold room than during exercise in the room at normal temperature.