Abstract 17468: Left Ventricular Remodeling Index (LVRI) in patients after breast cancer therapy in the long-term follow-up

Introduction: Cardiotoxic side effects are of concern in long-term survivors of left-sided breast cancer therapy. 3-dimensional conventional radiotherapy (3DCRT) deposits high doses in defined regions of the heart. Intensity modulated radiotherapy (IMRT) reduces local high-dose exposition at the expense of exposing more heart tissue to lower doses. Cardio-MRI was performed in this study to assess MRI-morphologic and functional alterations after 3DCRT and IMRT/ additional chemotherapy, with IMRT only performed in patients that would have been exposed to unacceptably high heart doses with 3DCRT. Methods: 49 patients with left-sided breast cancer (38 3DCRT and 11 IMRT; 20 patients with additional adjuvant chemotherapy (ACH) (13 3DCRT, 7 IMRT) were included prospectively. Baseline (pre-treatment) and 24 months post-treatment MRI was performed. With MRI, enddiastolic left ventricular mass (LVM), enddiastolic left ventricular volume (LVEDV) and stroke volume (SV) were assessed. LVRI was calculated with the formula LVM/LVEDV. Results: Mean dose for the whole heart was higher in IMRT than in 3DCRT patients (12.9±3.9 vs. 4.5 ±2.4 Gy). Larger regions received a higher radiation dose (>40Gy) in 3DCRT than in IMRT patients (3.3% vs. 1.3% of the whole heart). High local radiation dose > 50 Gy only occurred in the 3DCRT group (0.74% of the heart volume). After 24 months LVRI decreased significantly in patients with ACH (0.80 vs. 0.70, p=0.028). Non-significant decrease of LVRI was observed in the whole cohort (0.85 vs. 0.79), after IMRT (0.74 vs. 0.71), after 3DCRT (0.88 vs. 0.82) and without ACH (0.87 vs. 0.84). Decrease of LVRI in patients with ACH was caused by significant decrease of LVM (102.4 vs. 89.7 g, p=0.028) whereas LVEDV was stable (128.3 vs. 128.1g). In all groups, no significant decrease of SV could be assessed after 24 months. Conclusions: 24 months after therapy, significant decrease of LVRI due to decreased LVM could be found only in patients with additional chemotherapy. Radiotherapy alone did not have a significant impact on LVRI, LVM and SV. Low doses to the whole heart with IMRT did not cause significant decreases in LVRI, LVM and SV. LVM and LVRI are to be assessed in larger cohorts in patients with cancer therapy especially with additional chemotherapy.