Ž. Aims: The performance of a US-American scoring system Heart Failure Survival Score, HFSS was prospectively evaluated Ž . in a sample of ambulatory patients with congestive heart failure CHF . Additionally, it was investigated whether the HFSS Ž . might be simplified by assessment of the distance ambulated during a 6-min walk test 6ЈWT instead of determination of peak Ž . Ž oxygen uptake peak VO . Methods and Results: In 208 middle-aged CHF patients age 54 " 10 years, 82% male, NYHA class 2 . 2.3" 0.7; follow-up 28 " 14 months the seven variables of the HFSS: CHF aetiology; heart rate; mean arterial pressure; Ž . serum sodium concentration; intraventricular conduction time; left ventricular ejection fraction LVEF ; and peak VO , were 2 determined. Additionally, a 6ЈWT was performed. The HFSS allowed discrimination between patients at low, medium and high risk, with mortality rates of 16, 39 and 50%, respectively. However, the prognostic power of the HFSS was not superior to Ž . a two-variable model consisting only of LVEF and peak VO . The areas under the receiver operating curves AUC for 2 Ž . prediction of 1-year survival were even higher for the two-variable model 0.84 vs. 0.74, P -0.05 . Replacing peak VO with 2 Ž . 6ЈWT resulted in a similar AUC 0.83 . Conclusion: The HFSS continued to predict survival when applied to this patient sample. However, the HFSS was inferior to a two-variable model containing only LVEF and either peak VO or 6ЈWT. As the 2 6ЈWT requires no sophisticated equipment, a simplified two-variable model containing only LVEF and 6ЈWT may be more widely applicable, and is therefore recommended. ᮊ

Background Stereotactic body radiotherapy (SBRT) is an established local treatment method for patients with hepatic oligometastasis or oligoprogression. Liver metastases often occur in close proximity to radiosensitive organs at risk (OARs). This limits the possibility to apply sufficiently high doses needed for optimal local control. Online MR-guided radiotherapy (oMRgRT) is expected to hold potential to improve hepatic SBRT by offering superior soft-tissue contrast for enhanced target identification as well as the benefit of gating and daily real-time adaptive treatment. The MAESTRO trial therefore aims to assess the potential advantages of adaptive, gated MR-guided SBRT compared to conventional SBRT at a standard linac using an ITV (internal target volume) approach. Methods This trial is conducted as a prospective, randomized, three-armed phase II study in 82 patients with hepatic metastases (solid malignant tumor, 1–3 hepatic metastases confirmed by magnetic resonance imaging (MRI), maximum diameter of each metastasis ≤ 5 cm (in case of 3 metastases: sum of diameters ≤ 12 cm), age ≥ 18 years, Karnofsky Performance Score ≥ 60%). If a biologically effective dose (BED) ≥ 100 Gy (α/β = 10 Gy) is feasible based on ITV-based planning, patients will be randomized to either MRgRT or ITV-based SBRT. If a lesion cannot be treated with a BED ≥ 100 Gy, the patient will be treated with MRgRT at the highest possible dose. Primary endpoint is the non-inferiority of MRgRT at the MRIdian Linac® system compared to ITV-based SBRT regarding hepatobiliary and gastrointestinal toxicity CTCAE III or higher. Secondary outcomes investigated are local, locoregional (intrahepatic) and distant tumor control, progression-free survival, overall survival, possible increase of BED using MRgRT if the BED is limited with ITV-based SBRT, treatment-related toxicity, quality of life, dosimetric parameters of radiotherapy plans as well as morphological and functional changes in MRI. Potential prognostic biomarkers will also be evaluated. Discussion MRgRT is known to be both highly cost- and labor-intensive. The MAESTRO trial aims to provide randomized, higher-level evidence for the dosimetric and possible consecutive clinical benefit of MR-guided, on-table adaptive and gated SBRT for dose escalation in critically located hepatic metastases adjacent to radiosensitive OARs. Trial registration The study has been prospectively registered on August 30th, 2021: Clinicaltrials.gov, “Magnetic Resonance-guided Adaptive Stereotactic Body Radiotherapy for Hepatic Metastases (MAESTRO)”, NCT05027711.