Impact of Radiation Therapy on Diastolic Function and Cardiac Troponin I Levels in Cancer Patients Undergoing Contemporary Radiotherapy

Background: Radiation-associated cardiac disease (RACD) remains a clinically relevant late toxicity of thoracic radiotherapy. Although modern techniques have reduced cardiac exposure, myocardial injury may still occur. Methods and Results: We analyzed 355 patients with esophageal, lung, or left breast cancer who underwent baseline cardiac evaluation before cancer therapy. For the primary analysis, patients without radiotherapy (no RT; n=237) were compared with those who received radiotherapy involving the heart (cardiac RT; n=41). Patients who underwent thoracic radiotherapy without direct cardiac irradiation (n=77) were evaluated separately. Cardiac troponin I (cTnI) and echocardiographic parameters were assessed at 12 months. cTnI levels remained stable and showed no association with cardiac radiation exposure. Left ventricular ejection fraction was preserved, whereas the cardiac RT group exhibited lower septal e' velocity and E/A ratio. Higher cardiac radiation dose was associated with lower E/A ratio (R=-0.448, P=0.009) and septal e' velocity (R=-0.389, P=0.023). In multivariable logistic regression analysis, cardiac irradiation independently predicted a reduced E/A ratio (<0.8; odds ratio 2.46; 95% confidence interval 1.04-5.83; P=0.041). Conclusions: Cardiac irradiation was associated with declines in diastolic indices despite stable cTnI. Diastolic impairment may represent an early subclinical manifestation of RACD, underscoring the importance of echocardiographic monitoring and minimizing cardiac radiation exposure.