Cardiac wasting is not cardiac cachexia: the problem of the subjective/objective genitive in matters of the heart

Tessitore, Costelli et al. were among the first to report a previously unnoticed loss of heart mass in cachectic mice suffering from a severe tumor burden. At the time both the general consensus definition of cachexia and the cancer cachexia classification did not exist. In particular, cancer cachexia is a syndrome characterized by muscle wasting leading to body weight loss in the presence of cancer. More recently, Zhou et al. highlighted once more the existence of a tumor-induced loss of heart mass in a murine model of cancer cachexia. This study generated a new line of research aimed at exploring the mechanisms underlying cardiac wasting in the presence of cancer. Cardiac wasting in the presence of cancer-induced cachexia is distinct from and other than cardiac cachexia, i.e. the atrophy of skeletal muscle induced by cardiac pathologies. However, over the years we have noticed that expressions such as "cardiac cachexia", "cardiac atrophy", and "muscle cachexia"  - that sound alike but are very different - are often mistakenly used. In particular, we are afraid that these misunderstandings may suggest to inexperienced readers that cardiac cachexia is a form of cardiac muscle atrophy, which is not. To add insult to injury, some authors use the expression "muscle cachexia" meaning muscle atrophy, which, as a consequence, may suggest to naive readers that cardiac cachexia is a form of cardiac muscle atrophy. We aim here to clarify the terminology describing these conditions, so as to avoid the misleading use of related expressions: cardiac atrophy and cardiac cachexia may sound alike but are very different. In particular, it is the expression "cardiac cachexia" that raises a problem of ambiguity and should be handled with care.