Natural history of atrial septal defect.

The natural history of atrial septal defect becomes increasingly difficult to determine with the number of patients having operations. The expectation of life has been calculated for those surviving their first year by two quite independent methods: (I) from 121 reported necropsies and (2) by calculating the mortality rates each decade from 25 deaths among 167 personal or reported patients followed for 663 patient-years. They were patients rather than the ideal of unselected children, but many were symptomless when first seen and sent only because of their physical signs. The two methods gave close agreement about the percentages still living at the end of each decade, generally within +/- 1 or 2 per cent and only as much as +/- 4.5 per cent in the second decade. With the relatively small numbers involved, such close agreement is probably fortunate. The mortality rates are low for the first two decades, 0.6 and 0.7 per cent per annum. In successive decades they rise from 2.7, to 4.5, to 5.4, and 7.5 per cent per annum. One-quarter have died just before their 27th year, half by their 36th year, three-quarters by 50, and 90 per cent by 60 years. The arithmetical mean age of death is 37.5 +/- 4.5 years. The median is also 37 years. The mode is widely spread through the 3rd to 6th decades. All these figures are better than those for aortic stenosis, coarctation of the aorta, and pulmonary stenosis. In and after the fourth decade they approximate more closely to the figures for aortic stenosis and coarctation but are still better than those for pulmonary stenosis. They are improved on only by those with a persistent ductus.