Lone atrial fibrillation (AF) is AF in the absence of structural heart disease. Persistent lone AF is a paroxysm that does not spontaneously resolve. The article by Paraskevaidis et al in this issue of CHEST (see page 488) concerns the use of echocardiography to predict the successful cardioversion of persistent lone AF and, perhaps more importantly, the maintenance of sinus rhythm. To accomplish this, the authors used a relatively new echocardiographic measurement, the absence of a “notch” in the early systolic mitral annulus motion (if you will, the absence of NESMAM). Keep in mind that left atrial enlargement and other previously described echocardiographic predictors of the maintenance of sinus rhythm measure cardiac structure, and that structural disease is absent by definition in patients with lone AF. Left atrial appendage flow velocity1 has been used but is based on data from a population that has or is at risk for structural disease.