Changes in cardiac markers including B-natriuretic peptide in runners after the Boston marathon

In contrast to nonspecific elevations of myoglobin and creatine kinase-MB (CK-MB) in athletes due to exertional rhabdomyolysis of trained skeletal muscle.(1,2) reported increases in cardiospecific troponins after competition may indicate silent injury to the myocardium.(3-8) We therefore undertook serial testing of multiple cardiac markers used to diagnose early- and late-stage myocardial injury in the same group of middle-aged runners before and sequentially after 5 Boston marathons over 4 years. In addition to CK-MB and myoglobin, cardiac troponin I (cTnI) was tested by a qualitative rapid assay in 1997, a high-sensitivity reference method in 1998 to 2000, and a rapid quantitative method to detect acute myocardial infarction (AMI) in 2001 together with cTnT. Selective postrace single-photon emission computed tomography (SPECT) with technetium-99m sestamibi myocardial scintigraphy and B-natriuretic peptide (BNP) levels were used to assess microinfarction and transient left ventricular dysfunction, respectively.