P4420Is exercise-induced cardiac troponin release caused by skeletal muscle injury?

Background

Cardiac troponins (cTn) are highly sensitive and specific markers for cardiac injury and a key element in the diagnosis of acute coronary syndrome. Strenuous exercise is known to induce increases in cTn, but the causative factors remain ambiguous. It is also equivocal whether exercise induced skeletal muscle injury is associated with cTn elevation.

Purpose

The aim of this study was to identify independent predictors for the rise in cardiac troponin T (cTnT) and I (cTnI) concentration and to focus on the relationship between skeletal muscle injury measured by skeletal troponin I (skTnI) and cTn elevations after a marathon race in a large group of male recreational runners.

Methods

A total of 40 recreational runners participating in the marathon in our city were recruited. The study included baseline visit (prerace) and immediate post-race sampling.

Results

The post-marathon cTnT concentration rose above the reference limit in 38 (95%) participants and the detection limit for cTnI was exceeded in 34 (85%) participants. Similarly, a 10-fold increase in skTnI concentration was observed and elevated post-race values were seen in all participants. There was no significant correlation between the post-race cTnT or cTnT change and post-race skTnI (Spearman's rho = 0.249, p=0.122, rho = 0.285, p=0.074). However, post-race cTnI and change in cTnI were associated with post-race skTnI (rho = 0.404, p=0.01, rho = 0.460, p=0.003) and creatine kinase (r=0.368, p=0.019) concentration. Subjective exertion or self-reported muscle symptoms did not correlate with post-race cTnT, cTnI or skTnI levels.

Post-Race cTnT <40 Post-Race cTnT ≥40 p-value n=18 n=22 Age, years 53.3±12.2 44.0±11.9 0.002 Active training, years 12.0 (9.3) 17.0 (15.8) 0.190 Muscle symptoms 7 (38.9) 11 (52.4) 0.523 Creatinine kinase, ug/l 406 (137) 399 (319) 0.163 N-terminal proBNP ng/l 137±168 158±277 0.783 Skeletal Troponin I, ng/ml 28.6 (41) 56.7 (143) 0.199

Figure 1

Conclusions

Cardiac troponin became abnormal in almost all runners after marathon race. The exercise-induced rise in cardiac troponin I is related to simultaneous release of skeletal troponin I. The mechanism of this association remains uncertain, but clinicians should be cautious when interpreting post-exercise troponin levels without clinical symptoms and signs of myocardial ischemia.