Subclinical Cardiac Dysfunction Detected by Strain Imaging During Breast Irradiation With Persistent Changes 6 Weeks After Treatment

Purpose: To evaluate 2-dimensional strain imaging (SI) for the detection of subclinical myocardial dysfunction during and after radiation therapy (RT). Methods and Materials: Forty women with left-sided breast cancer, undergoing only adjuvant RT to the left chest, were prospectively recruited. Standard echocardiography and SI were performed at baseline, during RT, and 6 weeks after RT. Strain (S) and strain rate (Sr) parameters were measured in the longitudinal, circumferential, and radial planes. Correlation of change in global longitudinal strain (GLS % and Delta change) and the volume of heart receiving 30 Gy (V30) and mean heart dose (MHD) were examined. Results: Left ventricular ejection fraction was unchanged; however, longitudinal systolic S and Sr and radial S were significantly reduced during RT and remained reduced at 6 weeks after treatment [longitudinal S (%) -20.44 +/- 2.66 baseline vs -18.60 +/- 2.70* during RT vs -18.34 +/- 2.86* at 6 weeks after RT; longitudinal Sr (s(-1)) -1.19 +/- 0.21 vs -1.06 +/- 0.18* vs -1.06 +/- 0.16*; radial S (%) 56.66 +/- 18.57 vs 46.93 +/- 14.56* vs 49.22 +/- 15.81*; * P<.05 vs baseline]. Diastolic Sr were only reduced 6 weeks after RT [longitudinal E Sr (s(-1)) 1.47 +/- 0.32 vs 1.29 +/- 0.27*; longitudinal A Sr (s(-1)) 1.19 +/- 0.31 vs 1.03 +/- 0.24*; * P<.05 vs baseline], whereas circumferential strain was preserved throughout. A modest correlation between S and Sr and V30 and MHD was observed (GLS Delta change and V30 rho = 0.314, P = .05; GLS % change and V30 rho = 0.288, P = .076; GLS D change and MHD rho = 0.348, P = .03; GLS % change and MHD rho = 0.346, P = .031). Conclusions: Subclinical myocardial dysfunction was detected by 2-dimensional SI during RT, with changes persisting 6 weeks after treatment, though long-term effects remain unknown. Additionally, a modest correlation between strain reduction and radiation dose was observed. (C) 2015 Elsevier Inc. All rights reserved.