IFNG and hydrops fetalis: This is strengthened by the finding that patients with chronic HF have reduced circulating levels of IFN-γ compared with healthy controls, regardless of aetiology.29 Numerous studies have also reported a relationship between increased adrenergic activity and reduced IFN-γ production, which can be reversed by adrenergic blockade.30,31 This is particularly pertinent considering that BB are often prescribed for HF with known beneficial effects.