Heckbert SR, Jensen PN, Austin TR, et al. - Given that a greater risk of atrial fibrillation, stroke, and death, in relation to high levels of supraventricular ectopy has been observed but there exists little information regarding disparities by race/ethnicity in the extent of supraventricular ectopy, or concerning if high levels of supraventricular ectopy are related to impaired left atrial (LA) function and LA enlargement, thus, researchers addressed these topics herein. In the MESA (Multi‐Ethnic Study of Atherosclerosis), participant features and cardiovascular magnetic resonance measures of LA function as well as structure were examined in relation to average count of premature atrial contractions (PACs) per hour and average number of runs per day of supraventricular tachycardia. In adjusted regression analyses, more PACs/hour were reported in relation to older age, male gender, White race, increased N‐terminal pro‐B‐type natriuretic peptide, and a history of clinically detected atrial fibrillation. On average fewer PACs/hour were noted in Chinese and Hispanic participants vs White participants. Overall, findings revealed more PACs/hour, on extended ambulatory electrocardiographic monitoring, in relation to impaired LA function and LA enlargement. Information regarding the extent of atrial myopathy may be obtained by measuring supraventricular ectopy.