Spontaneous closure of atrial septal defects within the oval fossa

To estimate the incidence and timing of spontaneous closure of atrial septal defects within the oval fossa, to study the modalities for diagnosis, and predict the need for therapeutic intervention.

We reviewed retrospectively the medical records of patients with isolated atrial septal defects within the oval fossa, so-called "secundum defects", diagnosed between January 1990 and February 2003. Based on the initial echocardiographic evaluation, we divided defects into small ones measuring from 3 to 5 mm, medium ones from 5 to 8 mm, and large ones greater than 8 mm.

We identified 121 patients, 50 (41.3%) of whom had failed to thrive, and 14 (11.6%) had congestive heart failure. At a mean of 44.9 +/- 22.1 months following diagnosis, with a range from 12 to 102 months, the defects had closed spontaneously in 31 patients (25.6%). Of 22 patients having small defects, spontaneous closure occurred in 18 (82%) at a mean age of 18.9 +/- 10.2 months. Of 27 patients with defects of medium size, 12 (44%) either experienced spontaneous closure, or else the defect effectively became a patent oval foramen, at a mean age of 51.2 +/- 32.2 months. Only 1 (1.4%) of the 72 patients with a defect larger than 8 mm in size underwent spontaneous closure. The defects increased in size in 8 patients (6.6%). Intervention was necessary in 76 patients (63%) at a mean age of 75.5 +/- 15.2 months.

The initial size of a defect within the oval fossa at diagnosis is the best predictor of its natural history. Some defects increase in size with growth, irrespective of their initial size.