What Factors Delay Interatrial Communications Closure in the Oval Fossa?

Purpose: In most neonatal intensive care units, echocardiography is performed at the bedside. The lack of closure of interatrial communications (IACs) in the oval fossa can affect mortality and morbidity. This study aimed to establish the rate of spontaneous closure of IACs diagnosed in the neonatal period and predict the need for subsequent evaluation according to various factors, including defect size and shape.Methods: The study group comprised 1,242 newborns admitted between March 2017 and December 2020. We judged the closure of the IACs and evaluated the risk factors of each. Patients were classified into the absence or presence of IACs. The morphology of the IACs was classified into atrial septal defects, patent foramen ovale, and multiple holes.Results: A total of 317 patients (131 female, 186 male) were enrolled in the study, and the average defect size was 3.0±1.0 mm. An overall spontaneous closure rate of 89.9% was observed during an average follow-up interval of 5.1±1.1 months. When multiple Cox regression analyses were performed to analyze the risk factors for spontaneous closure, initial defect size was a significant factor. The optimal cut-off value for predicting spontaneous closure of the IAC was 3.05 mm, and the area under the receiver operating characteristic curve was 0.625 (95% confidence interval, 0.520 to 0.729). Preterm infants had a larger defect size corrected for birth weight and a higher closure rate than term infants.Conclusion: Other than large defect size, no factors delayed spontaneous closure. When defects in the oval fossa measure ≤3 mm, most patients experience spontaneous closure by 7 months of age.