Mitral regurgitation in the neonatal period is relatively rare. It can be secondary to a congenital malformation of the valve apparatus or mitral valve dysfunction and deformation secondary to myocardial dysfunction or volume load of the left ventricle. Less commonly, it can be due to coronary artery abnormalities leading to mitral valve papillary muscle ischaemia and subsequent dysfunction. Such coronary artery abnormalities include anomalous left coronary artery from pulmonary artery, left main coronary artery atresia, or a thromboembolic phenomenon. In this study, we describe a newborn with a dysplastic aortic valve causing obstruction of the os of the left coronary artery leading to progressive mitral insufficiency.
