Beta-blocker therapy for dynamic left-ventricular outflow tract obstruction

Background: In a small but significant group of elderly patients who present with breathlessness, dynamic left-ventricular outflow tract obstruction (DLVOTO) may be responsible for symptom generation. The aim of our study was to investigate the effect of beta-blockade on ventricular physiology and symptoms in patients with DLVOTO. Methods: We performed a pilot study in 15 patients (age 76±10 years, mean±S.D., 14 female) with symptoms of exercise intolerance (New York Heart Association, NYHA, class 2.7±0.5). All patients had normal resting left ventricular (LV) systolic function together with DLVOTO based on the presence of basal septal hypertrophy and the development of high outflow tract velocities on stress echocardiography. All were commenced on oral atenolol (mean dose 45±19 mg), but this could not be tolerated in four patients due to a deterioration in clinical status. Results: In the remaining 11 patients who could tolerate atenolol therapy, the rate pressure product was significantly lower (23%, P=0.028) and there was a marked reduction in LV outflow tract velocity (23%, P=0.001) following beta-blockade. Patient symptoms improved significantly following atenolol therapy, with a reduction in mean NYHA class from 2.8±0.4 to 1.5±0.5 (P