Nyboe C, et al. - Researchers report the longest follow-up time with and without closure in childhood and adulthood, compared with a general population cohort, in the largest to date nationwide cohort of atrial septal defect (ASD) patients. Findings revealed that compared with a general population cohort matched on birth year and gender, patients with ASD exhibited a higher long-term mortality, overall. Furthermore, those undergoing closure vs those not undergoing closure had a lower relative mortality.