Background:
Cancer therapy-related cardiac dysfunction (CTRCD) is a major long-term complication in breast cancer survivors receiving potentially cardiotoxic therapies. Exercise training has emerged as a promising preventive strategy; however, detailed characterization of cardiac health prior to treatment initiation remains limited. The Cardiac Health in Breast Cancer (CHiB) study investigates the effects of structured exercise training on cardiovascular health during breast cancer therapy. This analysis aimed to describe baseline echocardiographic and cardiac magnetic resonance (CMR) findings before chemotherapy and intervention initiation.
Methods:
CHiB is a prospective, single-center, randomized controlled trial including women with breast cancer undergoing potentially cardiotoxic (neo-)adjuvant chemotherapy. Participants were randomized to a six-month supervised high-intensity interval and resistance training program (intervention group, IG) or standard WHO physical activity recommendations (control group, CG). Baseline assessments comprised transthoracic echocardiography, including left ventricular ejection fraction (LVEF), diastolic function, left and right ventricular global longitudinal strain (LV/RV GLS), RV free wall strain (FWS), and left atrial strain, as well as CMR and cardiopulmonary exercise testing (CPET). The Heart Failure Association–International Cardio-Oncology Society (HFA-ICOS) risk score was calculated to estimate baseline CTRCD risk. Associations between cardiorespiratory fitness (VO₂peak) and echocardiographic, CMR, anthropometric, and HFA-ICOS parameters were investigated using age-adjusted linear regression analyses.
Results:
48 patients were enrolled (mean age 56 ± 11 years; BMI 26.7 ± 6.3 kg/m²; cT stage: median cT2 [range cT1–cT4], median HFA-ICOS score 2 [range 1–3]). Echocardiographic parameters were within physiological ranges, including LVEF (66.4 ± 7.7%), LV GLS (-19.6 ± 2.0 %), RV GLS (-22.2 ± 3.7%) and RV FWS (-26.5 ± 6.0%). Mean VO₂peak was 21.8 ± 6.1 ml/kg/min. CMR demonstrated preserved biventricular function (LVEF 61 ± 5%, RVEF 59 ± 6%) and normal myocardial tissue characteristics (native T1 1020 ± 25 ms, T2 52 ± 2.4 ms, extracellular volume (ECV) 25.4 ± 2.6%). Four patients showed signs of myocardial or pericardial inflammation of uncertain etiology. In age-adjusted linear regression analyses, no statistically significant associations between VO₂peak and individual cardiac parameters were observed. However, higher VO₂peak consistently demonstrated effect estimates suggestive of a more favorable cardiovascular phenotype, including lower BMI, more favorable LV-GLS, larger biventricular volumes, improved diastolic function, and lower HFA-ICOS scores.
Conclusion:
Breast cancer patients demonstrated preserved cardiac structure and function prior to initiation of potentially cardiotoxic chemotherapy despite reduced cardiorespiratory fitness. Although associations between fitness and individual cardiac parameters did not reach statistical significance, higher VO₂peak consistently aligned with a more favourable cardiovascular phenotype and lower estimated CTRCD risk. These findings provide a rationale for preventive exercise interventions aimed at preserving cardiovascular health during breast cancer treatment.
