Magnesium in heart failure: an old ion with new lessons

The serum magnesium level in humans reflects a complex interplay between numerous factors, all of which directly and mainly impact gastrointestinal absorption and renal excretion of the ion. On the continuum of this delicate balance, extreme values on both ends have been previously shown to be associated with adverse effects, ultimately translating in heart failure patients to reduced survival, with the strongest evidence—including that currently provided by Chimura et al.—correlating the latter with hyper- rather than hypo-magnesaemia. In line with these observations, the data presented by Yin and colleagues suggest magnesium supplementation is prognostically beneficial only in heart failure patients exhibiting lower-range serum magnesium levels and harmful among those with higher-range values. Still in question are the exact serum magnesium margins that should be sought, as well as the specific properties required of magnesium preparations in order to be considered safe and effective, in broader, more diverse populations of individuals with heart failure.