Late results after operations for left ventricular outflow tract obstruction.

The late results were evaluated of operations for the relief of left ventricular outflow tract obstruction in young patients, 1 to 18 years old, from the National Heart Institute who were followed up for at least 5 years and from recently reported studies with an average follow-up duration of 5 or more years. The operative mortality rate for the combined series was low: 1.9 percent of 522 patients with valvular aortic stenosis, 6.0 percent of 222 patients with fixed subvalvular aortic stenosis and 5.5 percent of 18 patients with hypertrophic subaortic stenosis. From the National Heart Institute series, gradients early postoperatively were decreased to less than 50 mm Hg in 88 percent (30 of 34) of patients with valvular, in 68 percent (15 of 22) of patients with subvalvular and in 88 percent (8 of 9) of patients with hypertrophic subaortic stenosis. Late survival rates for patients in the combined series were 90 percent (472 of 522), 86 percent (190 of 222), and 82 percent (14 of 17) in the three respective groups after mean follow-up periods of 5 to 14.4 years. All late survivors in the current series have had symptomatic improvement; 95 percent (58 of 61) are asymptomatic. However, actuarial analysis in these patients predicts that 50 +/- 8 percent of those with valvular and 44 +/- 10 percent of those with subvalvular aortic stenosis after 10 years will be free from the adverse postoperative events of residual or recurrent left ventricular outflow tract obstruction, clinically significant aortic regurgitation, reoperation, endocarditis or late death. With use of the same adverse postoperative events to determine satisfactory late results from the combined series, it was found that 54 percent (281 of 522) of those operated on for valvular, 54 percent (120 of 222) of those operated on for subvalvular and 78 percent (14 of 18) of those operated on for hypertrophic subaortic stenosis had satisfactory late results 5 to 14 years after operation. Of the patients having unsatisfactory late results, major hemodynamic abnormalities were detected in 55 percent (23 of 42) within 1 year postoperatively. Thus it appears that operations for many children with left ventricular outflow tract obstruction are palliative. These patients should have early postoperative assessment and continuing long-term follow-up evaluation during childhood, adolescence and adulthood.