MSTN and heart failure: For example, myostatin expression is elevated in the muscle of patients with COPD16 and shows a weak inverse association with muscle strength.1 In some studies of heart failure, serum myostatin levels were increased in patients with heart failure,33, 34 whereas others failed to find such an increase.35 Consistent with SMAD2/3 signalling promoting muscle wasting, anti‐myostatin and anti‐activin IIB receptor antibodies reduced muscle loss in mouse models of muscle wasting,36, 37 and a subset of these agents have entered clinical trials (www.clinicaltrials.gov reference NCT01321320).