[Heart rate adjustment of ST segment depression: a good idea, but what results?]

Since 1977, 30 original reports have been published regarding the heart rate adjustment of the ST segment depression. The aim of the investigators was to find a new criterion more sensitive and more specific than the conventional slope and depression of the ST segment. This is a well known index of ischaemia and it was expected to become more sensitive if adjusted with an index of oxygen demand (the heart rate). In order to have a historical perspective of the debate, all published reports on the ST segment heart rate adjustment were analyzed. The group of Leeds showed no overlap of values between patients without coronary artery disease and patients with one, two, and three vessel disease. The new method, called ST/HR slope, purported to predict the exact number of coronary arteries with critical stenoses. These results have never been duplicated in any other center with the same accuracy. Several authors determined the clinical usefulness of this method and obtained conflicting results. Even now a unanimous agreement has not been reached and the routine utilization of the method in exercise laboratories is still uncommon. From this controversy, it should be learned that a physiological rationale does not always correspond to a relevant clinical result. Only clinical practice can define the real value of a new instrument.