Background:
Endurance activities such as marathon running frequently lead to transient elevations of cardiac biomarkers, particularly hs-troponin T, creatine kinase (CK), and myoglobin, which typically normalize within 72 hours. However, persistent or markedly elevated values may indicate pathology such as acute myocarditis. Accurate differential diagnosis is crucial, as early recognition and guideline-directed management are essential to ensure safe return to sport and favorable prognosis.
Case Report:
A 21-year-old healthy male recreational marathon runner collapsed toward the end of a race after experiencing muscle cramps, back pain, and leg discomfort. Upon arrival of emergency services, he was confused, hypertensive with a systolic blood pressure difference of 40 mmHg, and complained of severe back pain. CT angiography excluded aortic dissection. ECG showed sinus tachycardia with T-wave inversion in lead III without ST-segment elevation. Laboratory tests revealed markedly elevated cardiac biomarkers (e.g., hs-cTnT: 447 ng/L; CK: 38,281 U/L; myoglobin: 16,729 µg/L). Echocardiography raised suspicion for right ventricular dilation. Cardiac MRI confirmed acute myocarditis based on the revised Lake Louise criteria. Supportive treatment included intravenous fluids and strict avoidance of NSAIDs. The patient remained hemodynamically stable and free of arrhythmias or chest pain. He was discharged after three days with a recommendation of complete abstinence from physical activity for three months.
Follow-Up:
At three-month follow-up, the patient reported good functional capacity, occasional palpitations, and no chest pain. Laboratory values were normal. Echocardiography showed normal left ventricular ejection fraction (LVEF 58%) and normal strain. Cardiac MRI demonstrated complete normalization of mapping parameters, with no myocardial edema, no late gadolinium enhancement (LGE), and no relevant pericardial effusion.
Discussion:
This case highlights the diagnostic challenge of interpreting elevated cardiac biomarkers in endurance athletes. While transient post-exercise elevations are common in healthy runners, persistent or extreme elevations, especially when accompanied by symptoms or abnormal imaging, warrant evaluation for pathology such as myocarditis. Cardiac MRI remains the gold standard for diagnosis and follow-up. The use of NSAIDs in the context of viral or inflammatory myocardial processes is particularly concerning; animal models have shown increased mortality and myocardial necrosis associated with NSAIDs. Accordingly, the 2025 ESC guidelines explicitly advise against NSAID use in suspected myocarditis. In this case, the patient had taken ibuprofen to enhance his race performance, possibly exacerbating subclinical myocardial inflammation.
Conclusion:
Recreational marathon runners with persistent cardiac biomarker elevation should undergo thorough evaluation. According to the recent ESC guidelines, Cardiac MRI is pivotal for diagnosis and risk stratification. With early diagnosis and strict adherence to current guidelines, full recovery and return to athletic activity is achievable.
