Status of exercise duration and metabolic equivalents in interpretation of exercise electrocardiography testing

Abstract

Both exercise duration and metabolic equivalent give an idea about the effort tolerance of the patient. Effort tolerance depends on several factors e.g. cardiac status, pulmonary status, neuromuscular status, psychological status, physical conditioning, age, sex, haemoglobin concentration etc. Therefore, diminished effort tolerance alone, in absence of other evidence, can not be taken as an indication of the presence or severity of coronary artery disease or left ventricular dysfunction. Regression equations used for calculation of metabolic equivalent (MET) include speed and inclination of the treadmill (stage of particular protocol) in addition to the duration of exercise. MET, therefore, gives a more correct impression about the workload achieved by a given patient. For the same reason, MET is useful for comparing the reports of different treadmill tests performed by different protocols at different times. It helps in assessing the progression of the disease. Regression equations used by most of the conventional treadmill systems do not include other factors that affect effort tolerance. These include the age, sex, and weight of the patient. This is an important limitation. Keywords: Coronary Artery Disease; Exercise Electrocardiography; Left Ventricular Function; Myocardial Ischemia; Metabolic Equivalent; Treadmill Test