A-type natriuretic peptides (ANP) have been proposed as biomarkers for atrial fibrillation (AF) and midregional-proANP plasma levels correlate with the duration of AF episodes.[6], [7] There are several sandwich immunoassays commercially available that measure the concentrations of ANP and its precursor protein proANP in human plasma; however, most are prone to fragmentation and may underestimate the release of the precursor due to the early degradation of crucial epitopes at the extreme ends of the molecule. This evidence concerns the gene NPPA and atrial fibrillation.