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Background: Atrial septal defect (ASD) is a congenital heart lesion that often remains undiagnosed until adulthood. The reasons for this may be multifactorial. It is, however, known that closure of a hemodynamically significant ASD improves exercise capacity. This study aimed to explore whether the aerobic capacity in late adolescence is associated with time to diagnosis and intervention in adult men with late diagnosis of an atrial shunt.

Methods: The Swedish Military Conscription Service Register contains data on exercise tests performed in late adolescence. By linking these data with the National Patient Register, 254 men with a later intervention for an ASD were identified.

Results: Interventions were performed at a mean of 26.5 +/- 7.9 years after the initial exercise tests. The mean absolute workload among those with a later diagnosed ASD was similar to those without a later diagnosed ASD (274 +/- 51W vs. 276 +/- 52 W, p = 0.49). Men with a higher exercise capacity (>= 1 SD) had their intervention earlier (21.9 +/- 8.6 years vs. 27.5 +/- 7.4 years, p < 0.001).

Conclusions: The aerobic exercise capacity was similar in adolescent men with later interventions for ASD compared to the reference population. Furthermore, those with high exercise capacity appeared to be diagnosed earlier. Thus, low exercise capacity may not be a feature of ASD during adolescence, but rather develop later in life as a natural progression of the disease.