Myocardial scintigraphy and cardiospecific creatine kinase responses in female and male athletes after strenuous exercise

Serum estimations of total creatine kinase (CK) and CK-MB form the most widely used serum determinants of myocardial infarction. We studied 12 female and 15 male athletes 3 days before, and one hour, 24 hours and 96 hours after a marathon race. The males were heavier (p<0.01) and trained more intensively (p<0.001). Serum estimations of total CK and CK-MB were performed. Mean (± SEM) CK and CK-MB became maximally elevated 24 hours after the race. In females CK was 1128 ± 339 IU/1 and CK-MB was 13 ± 3 IU/1. In males CK was 1399 ± 348 IU/1 and CK-MB was 28 ± 6 IU/1. There was no statistical difference between female and male enzymatic response. Technetium-99m pyrophosphate scintigraphy was normal in both sexes before and after the race. There was no correlation between the weight of the athlete and the maximum CK levels recorded, but the CK-MB response was higher in the well-trained athlete (r = 0.51, p<0.01). These data suggest that highly trained athletes of either sex are more likely to display false-positive indicators of myocardial infarction using CK-MB measurements.