Exercise Phenotyping Prior to Chemotherapy in Newly Diagnosed Multiple Myeloma (MM-Exercise)

MM-Exercise is a prospective, single-centre, observational pilot study of patients with newly diagnosed multiple myeloma who have not yet started chemotherapy and whose resting echocardiogram is unremarkable or only mildly abnormal (preserved left ventricular ejection fraction \[LVEF\] ≥50%, at most grade I diastolic dysfunction). The study tests whether a relevant proportion of these patients already exhibit a central (cardiac) limitation of exercise capacity - defined as a cardiac output to oxygen uptake slope (CO/VO2 slope) below 5 - despite the absence of overt cardiac disease on resting assessment, and whether this exercise-derived marker correlates with subclinical myocardial tissue abnormalities on cardiac magnetic resonance imaging (CMR) and with heart-failure hospitalisation and mortality over 12 months. Eighty patients referred in comparable numbers from the haemato-oncology departments will undergo a single comprehensive baseline assessment (medical and sports history, cardiac biomarkers, resting echocardiography, 6-minute walk distance, combined cardiopulmonary exercise testing with stress echocardiography \[CPETecho\], and CMR with T1-/T2-mapping and late gadolinium enhancement) prior to chemotherapy initiation, followed by in-person clinical follow-up visits 3 and 12 months after each patient's own baseline visit.

Inclusion Criteria: * Histologically or cytologically confirmed newly diagnosed multiple myeloma and chemotherapy not yet initiated * Resting echocardiogram with preserved left ventricular ejection fraction (≥50%) and at most mild (grade I) diastolic dysfunction with no echocardiographic signs of clinically manifest cardiac involvement * Age 18-99 years * Written informed consent * Sufficient German or English language skills Exclusion Criteria: * New York Heart Failure Association Class IV heart failure, or recent decompensated heart failure requiring inpatient recompensation * Suspected new or progressive coronary artery disease * Estimated glomerular filtration rate \