[Reproducible (latent) obstruction of the left ventricular outflow tract]

Left ventricular outflow tract obstruction (LVOTO) with flow acceleration in late systole (Vmax > or = 2.0 m/s and acceleration/ejection time [AT/ET] > or = 0.5) is often present in a latent form in left ventricular hypertrophy; it can be unmasked by administration of glyceryl trinitrate or with the Valsalva manoeuvre (preload reduction). It was investigated prospectively whether latent LVOTO also occurs on ergometric exercise.

61 patients (19 female, 42 male, mean age 55.5 +/- 12.9 years) with left ventricular hypertrophy at rest were examined by Doppler echocardiography at rest, under provocation with glyceryl trinitrate and the Valsalva manoeuvre, and during bicycle ergometry. Manifest LVOTO was already present before the test in 3 patients.

In 24 patients LVOTO occurred during the provocation (Vmax rose from 1.38 +/- 0.25 to 2.93 +/- 0.53 m/s; AT/ET rose from 0.47 +/- 0.16 to 0.68 +/- 0.09). In 19 of these 24 patients LVOTO also occurred during the ergometry. In four additional patients changes were marginal (AT/ET > or = 0.5; Vmax = 1.8 and 1.9 m/s, respectively). There was a highly significant correlation between provocation and ergometry with regard to Vmax, as well as AT/ET (with r = 0.84 and 0.76, respectively).

These findings show that provokable LVOT gradients are likely to occur during exercise to a similar degree as those on preload reduction. Thus, course of disease could possibly be influenced by early treatment in patients with left ventricular hypertrophy.