Discrete subaortic stenosis in adults: Increased prevalence and slow rate of progression of the obstruction and aortic regurgitation

OBJECTIVES We sought to determine the prevalence and rate of progression of left ventricular outflow tract obstruction (LVOTO) and aortic regurgitatio n (AR) in adults with discrete subaortic stenosis (DSS). BACKGROUND Discrete subaortic stenosis is an uncommon form of LVOTO, with r apid hemodynamic progression in children, but the prevalence and rate of pr ogression in adults have not been studied so far. METHODS The prevalence of DSS was determined in 2,057 consecutive adults diagnosed with congenital h eart disease (CHD). The relationship between LVOTO on Doppler echocardiogra phy and patient age was analyzed. Sequential changes in LVOTO and AR were d etermined for patients with two or more Doppler echocardiograms obtained wi th at least a two-year interval. RESULTS A total of 134 adults (mean age 31 +/- 17 years) were diagnosed wit h DSS. The prevalence was 6.5% for all adults with CHD. Sixty patients (44% ) had other associated CHD. The mean age of 29 patients who had undergone a n operation for DSS during their adult life (56 +/- 15 years) was significa ntly higher than that of 64 patients (27 +/- 13 years) who had not required a surgical intervention (p < 0.0001). A significant relationship between L VOTO and patient age (r = 0.61, p < 0.0001) was found: 21 +/- 16 mm Hg in p atients < 25 years old, 51 +/- 47 mm Hg for those between 25 and 50 years o ld, and 78 +/- 36 mm Hg for those > 50 years old. The LVOTO increased from 39.2 +/- 28 to 46.8 +/- 34 mm Hg (p = 0.01) during a mean follow-up of 4.8 +/- 1.8 years in 25 patients. The slope of the change in LVOTO was 2.25 +/- 4.7 mm Hg per year of follow-up. Aortic regurgitation was detected by colo r Doppler imaging in 109 patients (81%), but it was hemodynamically signifi cant in < 20%. An increase in the mean degree of AR over time was not signi ficant (baseline: 1.3 +/- 0.8; follow-up: 1.5 +/- 0.9; p = 0.096). CONCLUSIONS The prevalence of DSS is increasing in adults due to the greate r number of repaired CHDs that develop into evolutive DSS. In contrast to i nfants and children, adults with DSS show a slow rate of LVOTO progression. Aortic regurgitation is a common but usually mild and nonprogressive conse quence. The current indications for surgical intervention should be revised . (C) 2001 by the American College of Cardiology.