014 Regional Cardiac Dysfunction Determined by Radiation Dose in Patients With Breast Cancer: A Longitudinal Follow-Up Study

Abstract

Subclinical left ventricular (LV) dysfunction by 2D global longitudinal strain (GLS) immediately post radiotherapy (RT) and persisting at 12 months has been described in breast cancer patients. We hypothesised that persistent LV dysfunction may be regional and correlate with segmental RT. Echocardiography was performed at baseline, 6 weeks and 12 months post-RT on 61 chemotherapy-naïve women with left sided breast cancer. The amount of radiation received by individual LV regions and segments was quantified. Anterior and anteroseptal regions received the highest radiation dose, and inferior and inferolateral regions the lowest radiation dose. Within each region, there was a progressive increase in the radiation dose received from base to apex (apical>mid>basal segment). At 6 weeks, the greatest reduction in strain was in the anterior and anteroseptal regions, with the most significant reduction in the apical segments. At 12 months, despite improvement in strain, the percentage reduction in strain demonstrated a similar pattern. There was a significant interaction between both region and segment, on the percentage change in strain at 6 weeks (p<0.001) and 12 months (p=0.007). Mean differences in percentage change in strain between mid and basal regions, and apical and basal regions, demonstrated the most significant reductions in the anterior region at 6 weeks and 12 months (Table). RT causes segmental myocardial dysfunction, with areas receiving the highest RT demonstrating the largest impairment in strain, and these changes persist at 12 months. Correlation with clinical outcomes is required.Tabled 1TimeSegmentDifference Mid – BasalDifference Apical – BasalMean %SEp valueMean %SEp value6 weeksAnterior-6.611.72<0.001-19.542.08<0.001Anteroseptal-2.831.180.019-18.201.06<0.00112 monthsAnterior-4.541.970.023-15.792.18<0.001Anteroseptal-4.381.18<0.001-14.761.73<0.001 Open table in a new tab