(11Z)-16-[[2-(Methylamino)-2-oxoacetyl]amino]-11-hexadecenoic Acid-d3 is the labelled analog of (11Z)-16-[[2-(Methylamino)-2-oxoacetyl]amino]-11-hexadecenoic Acid (M286940), a regulator to cardiomyocyte contraction and a potential antiarrhythmic agent. (11Z)-16-[[2-(Methylamino)-2-oxoacetyl]amino]-11-hexadecenoic Acid is also a stable analog of 17,18-epoxyeicosatetraenoic acid which may be used to study the mechanism of regulation of cardiomyocyte contractility by eicosapentaenoic acid (E477800) metabolites.