The peptide offers numerous potential advantages, particularly for heart failure therapy: apelin is a potent vasodilator of arteries [7], [12] and veins [12], [13] thereby reducing pre- and afterload, antagonizes the renin-angiotensin system [4], has anti-fibrotic effects [14], and enhances the force of cardiac contractions [15]–[17]. Here, APLN is linked to heart failure.