Changes in Cardiac Function in Patients Receiving Radiation Therapy for Lung Cancer.

[INTRODUCTION] The cardiovascular toxicity of radiation therapy (RT) remains incompletely understood in patients with NSCLC. Our objective was to define changes in echocardiographic parameters of structure and function with RT and their associations with cardiac dose-volume metrics.

[METHODS] This multicenter, longitudinal, prospective cohort study included participants with NSCLC who received standard, curative-intent thoracic RT. Dose-volume metrics were extracted from centrally contoured cardiac substructures. Echocardiograms at baseline, end of RT, 6 months post-RT, and 12 months post-RT were core laboratory-quantified. Repeated-measures multivariable linear regression via generalized estimating equations estimated changes in echocardiographic measures and associations with dose-volume metrics.

[RESULTS] Across 125 participants, there was a modest worsening in left ventricular ejection fraction (LVEF) (p = 0.019), global longitudinal strain (p < 0.001), circumferential strain (p < 0.001), and Ea/Ees (p = 0.011) post-RT that largely recovered by 12 months. Cardiac dysfunction, defined as LVEF declines of at least 10% from baseline to a threshold value of less than 50%, occurred in 7.2% of participants at a median of 1.7 months after RT initiation. Mean heart dose was associated with LVEF declines (-1.1%, 95% confidence interval: -2.2 to 0.0 per interquartile range increase, p = 0.044), as was whole heart V30 (-1.4%, 95% confidence interval: -2.5 to -0.3 per interquartile range increase, p = 0.015); with multiple comparison adjustment, whole heart V30 remained significant (p = 0.030).

[CONCLUSIONS] On average, there were modest changes in cardiac function immediately after RT in patients with NSCLC, with a subset experiencing clinically relevant cardiac dysfunction. Although whole heart V30 was associated with LVEF declines, suggesting its relevance in RT planning, there is also a need for newer dose-volume measures.