Aerobic Fitness Is Related to Myocardial Fibrosis Post-Anthracycline Therapy

Adjuvant anthracycline chemotherapy for breast cancer is associated with cardiotoxicity and reduced cardiorespiratory fitness ((V)over dotO(2peak)). Purpose: We evaluated the impact of anthracyclines on left ventricular function and myocardial tissue characteristics using cardiovascular magnetic resonance (CMR) imaging to determine their relationship with (V)over dotO(2peak). Methods: Women with breast cancer who had not yet received treatment (No-AT, n = 16) and had received anthracycline treatment similar to 1 yr earlier (Post-AT, n = 16) and controls without cancer (CON, n = 16) performed a maximal exercise test and a comprehensive 3T CMR examination, including native myocardial T-1 mapping, where elevated T-1 times are indicative of myocardial fibrosis. ANOVA and linear regression were used to compare CMR variables between groups and to determine associations with (V)over dotO(2peak). Subgroup analysis was performed by categorizing participants as fit or unfit based on whether their (V)over dotO(2peak) value was greater or less than 100% of reference value for age, respectively. Results: Left ventricular end-diastolic volume, ejection fraction, and mass were similar between groups. Post-AT, T-1 times were elevated (1534 +/- 32 vs 1503 +/- 28 ms, P < 0.01), and (V)over dotO(2peak) was reduced (23.1 +/- 7.5 vs 29.5 +/- 7.7 mL.kg(-1).min(-1), P = 0.02) compared with CON. In No-AT, T-1 times and (V)over dotO(2peak) were similar to CON. In the Post-AT group, T-1 time was associated with (V)over dotO(2peak) (R-2 = 64%), whereas in the absence of anthracyclines (i.e., No-AT and CON groups), T-1 time was not associated with (V)over dotO(2peak). Regardless of group, all fit women had similar T-1 times, whereas unfit women Post-AT had higher T-1 than unfit CON (1546 +/- 22 vs 1500 +/- 33 ms, P < 0.01). Conclusions: After anthracycline chemotherapy, an elevated T-1 time suggesting greater extent of myocardial fibrosis, was associated with lower (V)over dotO(2peak). However, those who were fit did not have evidence of myocardial fibrosis after anthracycline treatment.

Automated summary

Adjuvant anthracycline chemotherapy for breast cancer is associated with increased myocardial fibrosis, which in turn is related to reduced cardiorespiratory fitness. However, this association is not observed in women who have not yet received treatment or in those without cancer.