Cardiac health and baseline fitness in breast cancer patients prior to a preventive training intervention in cardio-oncology: First results from the CHiB study

H. Colditz (Ulm)¹, E. Schwarz (Ulm)¹, L. Matits (Ulm)², J. Kersten (Ulm)³, S. V. W. Schulz (Ulm)¹, J. Kirsten (Ulm)², D. Buckert (Ulm)⁴, N. Nita (Ulm)⁴, M. Beer (Ulm)⁵, W. Janni (Ulm)⁶, V. Fink (Ulm)⁷, E. Leinert (Ulm)⁶, M. Kersten (Ulm)⁸, S. Klömpken (Ulm)⁵, F. Ebner (Ehingen)⁹, J. Schellenberg (Ulm)^2
1Universitätsklinikum Ulm Sektion für Sport- und Rehabilitationsmedizin Universitätsklinikum Ulm Ulm, Deutschland; ²Universitätsklinikum Ulm Sektion für Sport- und Rehabilitaionsmedizin Ulm, Deutschland; ³Herzplus Ulm Ulm, Deutschland; ⁴Universitätsklinikum Ulm Klinik für Innere Medizin II Ulm, Deutschland; ⁵Universitätsklinikum Ulm Klinik für Diagnostische und Interventionelle Radiologie Ulm, Deutschland; ⁶Universitätsklinikum Ulm Klinik für Frauenheilkunde und Geburtshilfe (Frauenklinik) - Universitätsklinikum Ulm Ulm, Deutschland; ⁷Universitätsklinikum Ulm Klinik für Frauenheilkunde und Geburtshilfe Ulm, Deutschland; ⁸Klinik für Frauenheilkunde und Geburtshilfe Ulm Ulm, Deutschland; ⁹ADK- Klinikum Frauenklinik - Frauenheilkunde und Geburtshilfe Ehingen, Deutschland

Background:
Breast cancer is the most common cancer in women, with over 2.3 million new cases per year and a five-year survival rate of over 90%. Longer survival increases the risk of cancer therapy-related cardiac dysfunction (CTRCD) up to 10%, for which effective primary prevention strategies are currently lacking. The Cardiac Health in Breast Cancer (CHiB) study investigates the effects of structured high-intensity interval (HIIT) and resistance training (HIRT) on the occurrence of symptomatic or asymptomatic CTRCD.

Methods:
CHiB is a single-center, randomized controlled trial including patients with histologically confirmed breast cancer undergoing cardiotoxic (neo-)adjuvant chemotherapy. Participants are randomized to a six-month supervised HIIT and HIRT program (twice weekly; intervention group, IG) or to standard WHO exercise recommendations (control group, CG). The primary endpoint is the occurrence of symptomatic and asymptomatic CTRCD, detected by cardiac imaging and myocardial biomarkers. Assessments include echocardiography with speckle tracking analysis, cardiac magnetic resonance (CMR), cardiopulmonary exercise testing (CPET), blood analyses, anthropometry and questionnaires at baseline, after six and twelve months.

Results: 
To date, 24 patients have been enrolled (mean age 56.7 ± 11.6 years; BMI 27.7 ± 6.1 kg/m²; cT stage: median cT2 [range cT1–cT4]). Five patients reported a family history of cardiovascular disease, and none had pre-existing cardiac conditions. All patients received their first cardiotoxic chemotherapy according to tumor entity and S3-Guideline for Breast Cancer (DKG, AWMF). Ten patients received neoadjuvant, and 14 adjuvant treatment. Randomization resulted in IG (n = 13) and CG (n = 11). At baseline, the mean VO₂peak was 21.9 ± 6.7 ml/kg/min, with 45% of all patients showing values below predicted normal ranges (83% in the < 50-year subgroup; 38% in the > 63-year-old subgroup). Left ventricular ejection fraction (LVEF, biplane by Simpson) was 63.7 ± 4.5%, left ventricular global longitudinal strain (LV GLS) -19.7 ± 1.9%, right ventricular GLS (RV GLS) -21.2 ± 2.8%. There were no significant baseline differences between IG and the CG (VO₂peak p = 0.593; LVEF p = 0.676; LV GLS p = 0.611; RV GLS p = 0.577).

Conclusion:
Baseline findings of the CHiB study demonstrate that a substantial proportion of breast cancer patients already have reduced cardiorespiratory fitness before initiating chemotherapy, while systolic cardiac function is preserved. These data emphasize the need for preventive training programs to maintain cardiovascular health during cancer therapy and provide a foundation for evaluating structured HIIT and HIRT in this population.