Persistent impairment in cardiopulmonary fitness after breast cancer chemotherapy

Purpose Anthracycline chemotherapy (AC) is associated with acute reductions in cardiopulmonary fitness (V˙O2peak). We sought to determine whether changes in V˙O2peak and cardiac function persisted at 12 months post-AC completion, and whether changes in cardiac function explain the heightened long-term heart failure risk. Methods Women with breast cancer scheduled for AC (n = 28) who participated in a nonrandomized trial of exercise training (ET; n = 14) or usual care (UC; n = 14) during AC completed a follow-up evaluation 12 months post-AC completion (16 months from baseline). At baseline, 4 months, and 16 months, participants underwent a resting echocardiogram (left ventricular ejection fraction; global longitudinal strain), a blood sample (troponin; B-type natriuretic peptide), a cardiopulmonary exercise test, and cardiac MRI measures of stroke volume (SV), heart rate, and cardiac output (Qc) at rest and during intense exercise. Results Seventeen women (UC, n = 8; ET, n = 9) completed evaluation at baseline, 4 months, and 16 months. At 4 months, AC was associated with 18% and 6% reductions in V˙O2peak in the UC and ET groups, respectively, which persisted at 16 months (UC, −16%; ET, −7%) and was not attenuated by ET (interaction, P = 0.10). Exercise Qc was lower at 16 months compared with baseline and 4 months (P < 0.001), which was due to a blunted augmentation of SV during exercise (P = 0.032; a 14% reduction in peak SV), with no changes in heart rate response. There was a small reduction in resting left ventricular ejection fraction (baseline to 4 months) and global longitudinal strain (between 4 and 16 months) and an increase in troponin (baseline to 4 months), but only exercise Qc was associated with V˙O2peak (R2 = 0.47, P < 0.01). Conclusion Marked reductions in V˙O2peak persisted 12 months after anthracycline-based chemotherapy, which was associated with impaired exercise cardiac function.