Cardiac abnormalities in a young athlete with severe pectus excavatum: a case report of a diagnostic loop between anatomical distortion and cardiomyopathy.

Background: Pectus excavatum (PEX) is the most common congenital chest wall deformity, occasionally associated with cardiac displacement and mild functional impairment. Its role in masking or mimicking cardiomyopathy remains poorly defined, particularly in athletes. Case summary: We report the case of a 24-year-old asymptomatic male athlete with severe PEX, frequent monomorphic premature ventricular contractions (PVCs), and mildly reduced left ventricular ejection fraction (LVEF). Despite successful PVC ablation and absence of genetic mutations, fibrosis, or structural abnormalities on cardiac magnetic resonance and electroanatomic mapping, the patient maintained borderline LV dysfunction. These findings raised the possibility of either a mild non-dilated left ventricular cardiomyopathy (NDLVC) or a reversible functional impairment due to chest wall distortion. Based on Italian guidelines, the patient was deemed ineligible for competitive sports. However, we explored how this case might be handled in other European countries with more permissive or flexible criteria. Discussion: This case underscores the diagnostic uncertainty posed by overlapping anatomical and functional findings, and the potentially profound impact of disqualification from sport on young athletes. It also reveals discrepancies in national approaches to eligibility and the interpretation of borderline findings. The case prompts reflection on the need for more harmonized guidelines and, in selected cases, structured shared decision-making processes involving expert centres and the athlete. Conclusion: In the evolving context of NDLVC, this case highlights the difficulty of acting in rigid frameworks and diagnostic loops, advocating instead for individualized, responsible decision-making that balances safety with athlete well-being.