Table 2

Definitions of Dynamic Left Ventricular Outflow Tract Obstruction

Hemodynamic StateConditionsOutflow Gradient
Basal obstructionRest≥30 mm Hg
NonobstructiveRest<30 mm Hg
Physiologically provoked<30 mm Hg
Labile obstructionRest<30 mm Hg
Physiologically provoked≥30 mm Hg
  • Either the peak instantaneous continuous wave Doppler gradient or the peak-to-peak cardiac catheterization gradient, which are equivalent in hypertrophic cardiomyopathy (73,74).

  • Gradients ≥50 mm Hg either at rest or with provocation are considered the threshold for septal reduction therapy in severely symptomatic patients.