Acute radiation effects on cardiac function detected by strain rate imaging in breast cancer patients.

PURPOSE: To investigate the occurrence of early radiation-induced changes in regional cardiac function using strain rate imaging (SRI) by tissue Doppler echocardiography. METHODS AND MATERIALS: We included 20 left-sided and 10 right-sided breast cancer patients receiving radiotherapy (RT) to the breast or chest wall. Standard echocardiography and SRI were performed before RT (baseline), immediately after RT (post-RT), and at 2 months follow-up (FUP) after RT. Regional strain (S) and strain rate (SR) values were obtained from all 18 left ventricular (LV) segments. Data were compared to the regional radiation dose.
RESULTS: A reduction in S was observed post-RT and at FUP in left-sided patients (S(post-RT): -17.6 ± 1.5%, and S(FUP): -17.4 ± 2.3%, vs. S(baseline): -19.5 ± 2.1%, p < 0.001) but not in right-sided patients. Within the left-sided patient group, S and SR were significantly reduced after RT in apical LV segments (S(post-RT): -15.3 ± 2.5%, and S(FUP): -14.3 ± 3.7%, vs. S(baseline): -19.3 ± 3.0%, p < 0.01; and SR(post-RT): -1.06 ± 0.15 s(-1), and SR(FUP): -1.16 ± 0.28 s(-1), vs. SR(baseline): -1.29 ± 0.27 s(-1), p = 0.01), but not in mid- or basal segments. Furthermore, we observed that segments exposed to more than 3 Gy showed a significant decrease in S after RT (S(post-RT): -16.1 ± 1.6%, and S(FUP): -15.8 ± 3.4%, vs. S(baseline): -18.9 ± 2.6%, p < 0.001). This could not be observed in segments receiving less than 3 Gy.
CONCLUSIONS: SRI shows a dose-related regional decrease in myocardial function after RT. It might be a useful tool in the evaluation of modern RT techniques, with respect to cardiac toxicity.