Composition of cardiac troponin release differs after marathon running and myocardial infarction
K E Juhani Airaksinen1,2, Tuomas Paana2, Tuija Vasankari3,2
1University of Turku, Turku, Finland juhani.airaksinen@tyks.fi.
Insights
Cardiac troponin T (cTnT) levels differ after marathon running versus myocardial infarction (MI). Post-exercise cTnT is mostly fragmented, unlike in MI where intact forms dominate.
Area of Science:
- Cardiology
- Exercise Physiology
- Biochemistry
Background:
- Elevated cardiac troponin T (cTnT) is common after strenuous exercise.
- The composition of cTnT release post-exercise is not well understood.
- Distinguishing exercise-induced cTnT from myocardial infarction (MI) is clinically important.
Purpose of the Study:
- To compare the molecular composition of cTnT released after a marathon race with that released during acute myocardial infarction (MI).
- To investigate the degree of cTnT fragmentation in marathon runners versus MI patients.
Main Methods:
- Plasma samples from 45 marathon runners and 84 type 1 MI patients were analyzed.
- A novel immunoassay measured long cTnT (intact/mildly fragmented), while a commercial assay measured total cTnT.
- The ratio of long to total cTnT (troponin ratio) was calculated to assess fragmentation.
Main Results:
- 82% of runners had elevated total cTnT (>14 ng/L).
- Runners showed a significantly lower troponin ratio (0.17) compared to MI patients (0.62), indicating greater fragmentation.
- Higher troponin release correlated with lower troponin ratios in runners, but higher ratios in MI patients.
Conclusions:
- Circulating cTnT after strenuous exercise is predominantly fragmented, unlike in type 1 MI where intact forms are more prevalent.
- The difference in troponin composition is more pronounced with higher troponin release levels.
- This distinct cTnT profile may aid in differentiating exercise-induced elevations from acute MI.
Objectives:
Elevations of cardiac troponin T (cTnT) levels are common after strenuous exercise. We assessed whether the composition of cTnT release after marathon race differs from that of acute myocardial infarction (MI).
Methods:
Troponin composition was analysed in plasma samples taken from 45 runners after marathon race and from 84 patients with type 1 MI. The concentration of long cTnT (intact and mildly fragmented cTnT) was measured with a novel upconversion luminescence immunoassay, total cTnT with a commercial high-sensitivity cTnT assay, and the ratio of long to total cTnT (troponin ratio) was determined as a measure of troponin fragmentation.
Results:
Total cTnT exceeded the upper reference limit (>14 ng/L) in 37 (82%) runners. Troponin ratio was lower in runners ((IQR) 0.17 (0.11-0.24) vs 0.62 (0.29-0.96), p<0.001). With increasing troponin release the troponin ratio decreased (r=-0.497, p<0.001) in marathon runners and the concentration of long cTnT remained in all runners below 8.4 ng/L. In contrast to marathon runners, troponin ratio increased (r=0.565, p<0.001) with the increase of cTnT release in patients with MI. The median total and long cTnT concentrations were lower in marathon runners than in patients with MI (25 ng/L vs 835 ng/L and 4.1 vs 385 ng/L, p<0.001 for both).
Conclusion:
In contrast to type 1 MI, only a small fraction of circulating cTnT exists as intact cTnT or long molecular forms after strenuous exercise and the difference in troponin composition is more pronounced in runners with higher troponin release.
Trial Registration Number:
NCT06000930.
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