Arterial pressure was recorded directly and continuously in 15 patients with angina pectoris while pain was repeatedly induced by exercise of various types and severity. In every case, the precipitation of angina could be consistently related to the level reached by the product of heart rate and systolic blood pressure (corrected when necessary for changes in ejection time). This relationship persisted even when there were large variations in the type, intensity, and duration of the exercise and was also maintained in a patient in whom spontaneous and emotional episodes of pain were observed. A substantial improvement in exercise tolerance occurred in one patient and this was completely accounted for by a reduction in the circulatory response to exercise. It was concluded that the precipitation of angina is normally the result of a rise in the work of the myocardium to a critical level which is essentially fixed in each patient. The varying ease with which pain is provoked on different occasions can usual...

Relation of Heart Rate and Systolic Blood Pressure to the Onset of Pain in Angina Pectoris

The electrocardiographic response to exercise was compared with the results of coronary angiography in 89 patients with Type II hyperlipoproteinemia who had previous myocardial infarction ...

https://www.nejm.org/doi/pdf/10.1056/NEJM197508212930801?listPDF=true

Limitations of the electrocardiographic response to exercise in predicting coronary-artery disease.

We evaluated the diagnostic accuracy of exercise-induced ST-segment depression in detecting coronary-artery disease by applying the likelihood-ratio formulation of Bayes's theorem to stress-test data, which were partitioned into half-millimeter ranges of depression. The graphic relation between the predictive value of a given test result and the pretest risk of disease in the test subjects was obtained for each of these half-millimeter intervals. This method reveals that the predictive value of testing depends on the degree of ST-segment depression, and that the pretest risk of coronary-artery disease is an important determinant of the predictive value of any test result in the individual patient. These findings suggest that the use of the terms "positive" and "negative" are inappropriate to describe most stress-test results. Instead, the results should be interpreted in terms of a continuum of risk based on the extent of ST-segment depression.

https://www.nejm.org/doi/pdf/10.1056/NEJM197709292971301?listPDF=true

Bayesian Analysis of Electrocardiographic Exercise Stress Testing

Two hundred fifty-one patients (195 male and 56 females) referred for evaluation of chest pain were studied by multistage submaximal stress testing and selective coronary arteriography. In men with positive exercise tests the incidence rate of true positive exercise test results--that is, positive tests associated with 75 percent of greater coronary stenosis--was 89 percent in contrast to a 33 percent incidence rate of true positive exercise test results in women. The incidence rate of false positive excercise test results--that is, positive tests associated with no coronary stenosis or less than 50 percent stenosis--was 8 percent in men in contrast to 67 percent in women. Conversely, the incidence rate of false negative exercise test results (that is, negative exercise tests associated with 75 percent or greater coronary stenosis) was higher in men (37 percent) than in women (12 percent). It is concluded that in men a positive multistage stress test is useful in predicting the presence of significant coronary artery disease although a negative stress test cannot be relied upon to rule out the presence of significant disease. In women, a positive exercise test is of little value in predicting the presence of significant coronary artery disease, whereas a negative test is quite useful in ruling out the presence of significant disease. New criteria should be developed for stress testing of women.

Significant sex differences in the correlation of electrocardiographic exercise testing and coronary arteriograms

ALTHOUGH EXERCISE STRESS TESTING FOR CARDIAC PATIENTS has been in use for nearly 50 years, widespread acceptance of the technique as an important diagnostic tool in cardiology has been accomplished only recently. This has occurred with the recognition that patients with cardiac disease, even in advanced degree, can perform exercise safely under controlled conditions, and that objective information regarding cardiac functional capacity and the presence or absence of myocardial ischemia can be determined. In addition, epidemiologic follow-up studies and correlative studies comparing exercise electrocardiographic findings with coronary arteriograms have provided documentation of the sensitivity and specificity of the test in patients with coronary artery disease. In spite of considerable scientific input into this field in the last ten years, controversy regarding the usefulness and role of exercise stress testing in a variety of clinical settings persists.' This review will consider those aspects of exercise testing most relevant to the practicing physician. Several comprehensive monographs dealing with various aspects of this field have been published recently.2-8 The reader is referred to these sources for technical details or further discussion of some of the material covered here.

Exercise stress testing.

Standardization of an exercise electrocardiographic test for myocardial ischemia is desirable. Standardization of exercise should be based upon a standardized challenge to the coronary circulation, not upon a standardized challenge to the skeletal muscles, for the stresses upon the heart are not identical. With the use of heart rate during exercise as an index of cardiac stress, the levels of exercise prescribed on the basis of age, sex, and weight in standard "two-step" test tables produce widely varying levels of cardiac stress-sometimes too low to induce significant ST-segment depression in patients with angina pectoris and, occasionally, much greater than necessary to produce such diagnostic electrocardiographic changes. The graded exercise test, using 85 per cent of the maximal age-predicted heart rate that may be induced by exercise, produces a closer approximation of a standardized cardiac stress, regardless of age, sex, or body build. Its use with angina pectoris patients and normal subjects resul...

Exercise Graded by Heart Rate in Electrocardiographic Testing for Angina Pectoris

A computer program has been developed which clarifies the distorted exercise ECG and performs desired measurements of it which are reported in the laboratory almost immediately, so that the program can be used as an aid to exercise test monitoring. We have introduced a new measurement of the ECG, the negative ST (—ST) integral, which while unfamiliar to the eye is readily performed by computer. A —ST integral value of 7.5 µv-sec during exercise served to separate a normal group from a group with angina pectoris. Strenuous exercise was often necessary to elicit positive responses in diseased subjects, and the graded exercise test was found well-suited for this purpose. Use of a computer program as an investigative instrument in its own right, rather than as a means of duplicating classical human measurements, shows promise for improving the diagnosis of ischemic heart disease.

L. T. Sheffield

Papers

Exercise Graded by Heart Rate in Electrocardiographic Testing for Angina Pectoris

On-line Analysis of the Exercise Electrocardiogram

Factors affecting the maximal heart rate during extreme exercise.