Radiation Dose Determines Segmental Cardiac Dysfunction in Breast Cancer

Abstract

Background: In breast cancer patients, subclinical left ventricular (LV) dysfunction by 2D global longitudinal strain (GLS) immediately following radiotherapy (RT) and persisting at 12 months has been described. Hypothesis: Subclinical LV dysfunction may be differential and correlate with the amount of segmental RT. Methods: Transthoracic echocardiograms were performed at baseline (pre-RT), 6 weeks and 12 months post-RT on 21 chemotherapy-naïve women with left sided breast cancer. The amount of radiation received by individual LV segments was quantified. Results: LV GLS and segmental strain were significantly decreased following RT (Table 1); a significant reduction was noted in the apical segment. In all regions (basal, mid and apical), the least change in strain occurred in the posterior segment (i.e. the segment receiving the minimum radiation dose), while maximum and significant decreases occurred in the anterior, anteroseptal, and lateral segments, and coincided with these segments receiving a higher radiation dose (>13 Gy).Table 1ParameterBaseline6 weeks12 monthsP valueRT dose (Gy)LV GLS (%)−22.0 ± 2.7−20.4 ± 2.6−20.1 ± 2.30.03*Total = 9.0Basal strain (%)−18.2 ± 2.9−17.4 ± 2.2−16.6 ± 3.00.211.7Mid strain (%)−20.2 ± 2.8−19.4 ± 2.2−18.8 ± 2.50.164.9Apical strain (%)−27.3 ± 3.8−25.4 ± 4.2−25.1 ± 3.60.06*20.5Lateral strain (%)−21.9 ± 3.9−19.9 ± 3.5−18.8 ± 3.90.009*13.4Anterior strain (%)−21.9 ± 4.1−21.1 ± 3.7−18.5 ± 4.50.04*16.4Anteroseptal (%)−23.1 ± 4.2−20.5 ± 3.3−21.4 ± 3.20.06*15.8Septal (%)−22.2 ± 3.3−20.6 ± 2.5−20.8 ± 2.40.1410.8Inferior (%)−21.5 ± 3.2−22.5 ± 3.5−21.8 ± 3.10.486.7Posterior (%)−22.0 ± 4.7−19.6 ± 3.9−19.6 ± 3.70.454.1 Open table in a new tab Conclusion: RT causes segmental myocardial dysfunction, and areas receiving the highest RT demonstrate the largest impairment in strain.