In discrete fixed subaortic stenosis, surgery is indicated when the systolic gradient (Gmax) between the left ventricle (LV) and the aorta exceed 50mmHg or in the presence of significant aortic regurgitation (AR). The aim of this study was to determine the factors that influence the progression of the obstruction and the appearance of AR.

Retrospective serial echocardiographic review of 19 patients, mean age 16 years (2 years–38 years), with fixed discrete subaortic stenosis that didn’t require surgery (initial Gmax at inclusion<50mmHg and without any symptom). The mean follow-up was 5.42 years. The progression of gradient is defined by the formula (Gmax at follow up−initial Gmax).

The mean velocity of increasing of Gmax was 2mmHg/year. This progression was correlated to the patient's age (cutoff=15 years, r=−0.5, P=0.02), and the initial value of the Gmax (cutoff=40mmHg, r=0.43, P=0.04). The appearance or the aggravation of aortic regurgitation was determined by: the initial grade of AR (r=0.64; P=0.003), initial Gmax (r=0.65; P=0.002), progression's velocity of Gmax (r=0.47; P=0.04), and distance between the membrane and the aortic cusps (cutoff=5mm, r=0.49; P=0.03). LV hypertrophy was influenced by the velocity of progression of obstruction (>2mmHg/year).

The identification of factors determining the evolution of discrete subaortic stenosis (age<15 years, initial Gmax>40mmHg, distance membrane cusps>5mm) allow an adequate screening of patients that will require early operation.