Hypertrophic subaortic stenosis: Clinical and hemodynamic effects of long-term propranolol therapy

Thirteen patients with hypertrophic subaortic stenosis underwent right and transatrial septal left heart catheterization. Outflow obstruction was measured in the resting state and during a variety of stimulating maneuvers before and after the intravenous administration of 150 μg/kg of propranolol. The patients were then treated with orally administered propranolol and followed up for an average period of 17 months. Nine patients were available for a second catheterization, during which detailed hemodynamic measurements were repeated. Most patients had an initially favorable response to propranolol. However, 3 with an initially good response had a return of symptoms during the period of study. The initial clinical response appeared to correlate with the reduction of outflow obstruction seen after intravenous administration of propranolol. The long-term clinical course correlated with the hemodynamic findings at the second catheterization. The severity or lability of the outflow obstruction during the initial catheterization did not appear to have predictive value for the patient's response to long-term therapy. Propranolol had a favorable effect on the symptomatic state of the patients, but did not appear to change the course of the underlying disease.