Metabolic changes during exercise testing of patients with ischaemic heart disease

Nineteen patients who had recovered from a mild to moderately severe myocardial infraction 6--18 months previously were studied in order to investigate the relationship between the severity of myocardial insufficiency and metabolic changes developing during and after exercise. The patients were compared with six controls by means of a graded exercise test on a treadmill. Electrocardiographic records were made and blood pressure measured during and after the exercise and venous blood samples were taken for measurement of lactate, pyruvate, glycerol and free fatty acids. In five patients with moderate or advanced ischaemic electrocardiograph changes the blood lactate and pyruvate mean concentrations continued to rise up to a further 50% after they stopped exercising. The other patients, including some who developed symptoms suggestive of myocardial ischaemia, and all the controls, failed to show these marked increases in blood concentrations after the exercise. We conclude that the development of myocardial insufficiency during exercise is associated with marked increases in lactate and pyruvate concentrations in the peripheral blood particularly after the exercise has ceased.