Changes in serum concentrations of markers of myocardial injury following treadmill exercise testing in patients with suspected ischaemic heart disease.

Background: The treadmill exercise test (TEST) is frequently used in patients with suspected ischaemic heart disease to establish a diagnosis and estimate future risk. However, its predictive value is poor. We aimed to investigate whether measurement of biochemical markers of myocardial injury could improve the diagnostic value of the procedure.

Material And Methods: Twenty-four subjects with suspected acute coronary syndrome underwent a treadmill exercise stress test. Of these 13 had had a previous myocardial infarction and two had a past history of coronary artery bypass grafting. Nine subjects were found to be positive for coronary ischaemia during the treadmill test. Serum cardiac markers (total creatine kinase [CK], CK-MB, Troponin I and Troponin T) were measured pre-TEST, and 0, 1, 2, 4, 8 and 24 hours following the treadmill test.

Results: Total CK remained within the reference range for all subjects and showed no significant rise. However, mean serum concentrations of CK-MB were significantly higher than pre-test values at 2 hours (p < 0.03) following treadmill exercise testing in subjects who had a positive exercise stress test, but not in those with a negative test. In the subjects with a positive stress test, CK-MB levels returned to pre-Test value by 24 hours. Levels of neither serum troponin I, nor troponin T altered significantly at any point.

Conclusion: The measurement of CK-MB, but not cardiac troponins may add to the diagnostic utility of the TEST.