AimsCachexia, a common manifestation of malignant cancer, is not only associated with weight loss, but also with severe cardiac atrophy and impaired cardiac function. Here, we investigated the effects of ACM‐001 (0.3 or 3 mg/kg/day) in comparison to carvedilol (3 or 30 mg/kg/day), metropolol (50 or 100 mg/kg/day), nebivolol (1 or 10 mg/kg/day) and tertatolol (0.5 or 5 mg/kg/day) on cardiac mass and function in a rat cancer cachexia model.Methods and resultsYoung male Wistar Han rats were inoculated i.p. with 10⁸ Yoshida hepatoma AH‐130 cells and treated once daily with verum or placebo by gavage. Cardiac function (echocardiography), body weight and body composition (nuclear magnetic resonance scans) were assessed. The hearts of animals were euthanized on day 11 (placebo and 3 mg/kg/day ACM‐001) were used for signalling studies. Beta‐blockers had no effect on tumour burden. ACM‐001 reduced body weight loss (placebo: −34 ± 2.4 g vs. 3 mg/kg/day ACM‐001: −14.8 ± 8.4 g, p = 0.033). Lean mass wasting was attenuated (placebo: −16.5 ± 2.34 g vs. 3 mg/kg/day ACM‐001: −2.4 ± 6.7 g, p = 0.037), while fat loss was similar (p = 0.4) on day 11. Placebo animals lost left ventricular mass (−101 ± 14 mg), which was prevented only by 3 mg/kg/day ACM‐001 (7 ± 25 mg, p < 0.01 vs. placebo). ACM‐001 improved the ejection fraction (EF) (ΔEF: placebo: −24.3 ± 2.6 vs. 3 mg/kg/day ACM‐001: 0.1 ± 2.9, p < 0.001). Cardiac output was 50% lower in the placebo group (−41 ± 4 ml/min) compared to baseline, while 3 mg/kg/day ACM‐001 preserved cardiac output (−5 ± 8 ml/min, p < 0.01). The molecular mechanisms involved inhibition of protein degradation and activation of protein synthesis pathways.ConclusionThis study shows that 3 mg/kg/day ACM‐001 restores the anabolic/catabolic balance in cardiac muscle leading to improved function. Moreover, not all beta‐blockers have similar effects.