GZMK and hydrops fetalis: In addition, increases in cardiac GRK-transcripts have been shown to correlate well with disease severity in HF patients [44], suggesting that β1EC2-CP treatment alone or—on a molecular level even more efficient—combined with a β1-receptor blocking agent (which corresponds better to the current clinical requirements and treatment guidelines) might also act beneficially in anti-β1EC2-mediated human heart failure.