Multifactorial analysis of changes in heart rate during exercise in patients with ischemic heart disease as a method of evaluating myocardial reserve

: An attempt has been made to elucidate causes of heart rate change during exercise in anginal patients, using multifactorial mathematical analysis. Seventy-one patients underwent bicycle ergometry and the intravenous ergometrin test. Heart rate variation was found to be unrelated to the type of stress (bicycle ergometry or Master's test), or the presence or absence of ischemic ECG changes during an attack of pain. During exercise, heart rate shifts preceding an anginal attack are similar to those in patients with painless response to stress. At the onset of pain, an abrupt rise in heart rate is seen, its magnitude being particularly great in postmyocardial infarction patients with low physical stress tolerance and high sensitivity to ergometrin. Myocardial insufficiency may be the cause of excessive tachycardia in this category of patients. In patients with high stress tolerance in the absence of ergometrin sensitivity, increased sensitivity to endogenic catecholamines may be a cause of tachycardia during an anginal attack.