In animal models and in humans, circulating NPY levels are elevated during acute coronary syndromes,12 LV dysfunction,13,14 and in CHF.15,16 Early studies, before the advent of modern medical and interventional treatment, associated peripheral venous NPY levels with 1 year mortality in patients with acute MI or HF admitted to a coronary care unit.14 These studies only measured NPY-like activity, whereas our assay has a very low limit of detection (approximately 3 pg/mL) and high specificity, with 0% cross-reactivity with structurally similar peptides. This evidence concerns the gene NPY and hydrops fetalis.