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An assessment was made of the ability of an ergometric test to detect coronary patients in evaluating the reliability of the effort test, which is mainly important when it gives the percentage of coronary patients that can be discovered at an early stage during screening. The concept of sensitivity and specificity is analysed with respect to the diagnostic criteria employed. Blood pressure, heart rate and oxygen consumption are discussed in their rôle of leading parameters and the appraisal made of the diagnostic significance of a below-normal ST level in the literature is examined. Junctional falls in level and depression of the J point are also discussed. Cases in which a below-normal ST segment level is not associated with coronary disease are examined.

The historical development of the stress-test in the diagnosis of coronary insufficiency has been examined from the first observations about 1930 regarding changes in the repolarization phase during effort in coronary patients, up to modern tests with the ergometer bicycle and treadmill. Starting from the consideration that Master's Test is still the most commonly used in clinical practice, the limitations of tests of this type are highlighted and the discussion also covers the techniques and parameters now considered of greatest importance in cardiopathy diagnosis and evaluated by means of modern maximal stress tests. The results of a first period of work involving tests using the treadmill are reported. The methodology is discussed and the symptoms or ECG data that had suggested the test be used are related to the patient's origin (out-patient or hospitalized) and with the test's positivity or negativity. The high incidence of unstable ST syndrome, especially in the female sex, is also stressed. If this is not thoroughly investigated functionally (hyperventilation, Valsalva, etc.) it could be the cause of a large number of false positives. The lack of danger in the maximal stress test, even in cardiopaths, is confirmed together with the extreme ease with which nearly all patients manage to perform the test on the treadmill. Stress is also laid on the fact that the stress test is functional, unlike coronarography which is purely morphological, and the two examinations are thus complementary in the diversity of information they provide.