Cardiac Troponin Fragmentation After Heavy Physical Exercise The MaraCat2 Study

Background Elevations of commercial cardiac troponin T (total cTnT) levels are common after strenuous exercise, but there is limited information on whether the troponin composition differs from myocardial infarction (MI). Methods Troponin composition was analyzed in heparin plasma samples taken from 45 runners <1 h after marathon race and from 45 patients with Type 1 MI <12 h after the pain onset. The concentration of long molecular forms of cTnT (long cTnT) was measured with a novel upconversion luminescence assay, total cTnT was measured with a commercial high-sensitivity cTnT assay, and the ratio of long to total cTnT (troponin ratio) was determined. Results Total cTnT exceeded the upper reference limit (>14 ng/l) in 37 (82%) runners. The median total and long cTnT concentrations and the troponin ratio were higher (113 ng/l vs. 25 ng/l, 57 ng/l vs. 4.1 ng/l, and 0.36 vs. 0.17, respectively) in patients with MI than in marathon runners (p <0.001 for all comparisons). Troponin ratio decreased (r = -0.497, p <0.001) in marathon runners and increased (r = 0.466, p = 0.001) in patients with MI with increasing troponin release. In the receiver operating characteristics curve analyses of all subjects with cTnT release >14ng/l and those with 15-100 ng/l, long cTnT showed good predictive power with the area under the curve 0.969 (CI95% 0.939-1.000) and 0.937 (95% CI, 0.877–0.996) in discriminating marathon runners from MI patients. The respective values for total cTnT were 0.892 (CI95% 0.823-0.960) and 0.778 (95% CI, 0.656–0.901). Conclusions In contrast to Type 1 MI, after strenuous exercise only a small fraction of circulating cTnT exists as intact cTnT or long molecular fragments. The difference in troponin composition could be of diagnostic value when evaluating post-exercise cTnT elevations in subjects with chest complaints. Registration URL: ; Unique identifier: [NCT06000930][1] What Is New? What Are the Clinical Implications? ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial ; Unique identifier: [NCT06000930][1] ### Funding Statement This work was supported by the Finnish Foundation for Cardiovascular Research, Helsinki, Finland, Clinical Research Fund (EVO) of Turku University Hospital, Turku, Finland, the Finnish Society of Clinical Chemistry, Helsinki, Finland, the Turku University Foundation, Turku, Finland, and the Varsinais-Suomi Regional Fund of the Finnish Cultural Foundation, Turku, Finland. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All participants provided a written informed consent. The study complies with the Declaration of Helsinki as revised in 2013 and the study protocol was approved by the Medical Ethics Committee of the Hospital District of Southwest Finland. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Details of the patients, methods, and data supporting the present findings are available from the corresponding author on reasonable request. * MI : Myocardial infarction cTnT : Cardiac troponin T mAb : monoclonal antibodies aar : amino acid residues AUC : Area under the curve ROC : Receiver operating characteristics [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT06000930&atom=%2Fmedrxiv%2Fearly%2F2024%2F05%2F08%2F2024.05.07.24307024.atom