Variability of left ventricular outflow tract gradient during cardiac catheterization in patients with hypertrophic cardiomyopathy

JACC Cardiovasc Interv. 2011 Jun;4(6):704-9. doi: 10.1016/j.jcin.2011.02.014.


Objectives: This study characterizes left ventricular outflow tract (LVOT) gradient variability in patients with hypertrophic cardiomyopathy (HCM) during cardiac catheterization.

Background: Management of HCM is directed by the presence and magnitude of LVOT obstruction. The magnitude and clinical impact of spontaneous variability during a single cardiac catheterization has not been described.

Methods: Fifty symptomatic patients with HCM (mean age 55 ± 15 years; 48% men) underwent cardiac catheterization with high-fidelity, micromanometer-tip catheters and transseptal measurement of left ventricular pressures. Obstruction was defined as resting LVOT gradient ≥ 30 mm Hg and severe obstruction as ≥ 50 mm Hg. Variability in LVOT gradient was calculated as the difference of the largest and smallest LVOT gradients in the absence of provocative maneuvers or interventions.

Results: The largest LVOT gradient was 54.6 ± 56.4 mm Hg. The spontaneous variability in LVOT gradient was 49.0 ± 53.1 mm Hg (range 0 to 210.8 mm Hg, median 15 mm Hg). Discrepant classification of resting LVOT gradient severity was possible in 25 patients (50%). Twenty patients (40%) with severe obstruction could have been misclassified with regard to obstruction severity.

Conclusions: In patients with HCM, the LVOT gradient fluctuates significantly during a single hemodynamic assessment. Spontaneous variability could lead to misclassification of obstruction severity in one-half of studied patients. The dynamic nature of LVOT obstruction must be considered when assessing resting hemodynamics or the success of a given intervention during cardiac catheterization.

MeSH terms

  • Aorta / pathology*
  • Cardiac Catheterization*
  • Cardiomyopathy, Hypertrophic / complications
  • Cardiomyopathy, Hypertrophic / diagnosis*
  • Cardiomyopathy, Hypertrophic / pathology
  • Cardiomyopathy, Hypertrophic / therapy
  • Decision Making
  • Female
  • Health Status Indicators
  • Hemodynamics
  • Humans
  • Male
  • Manometry
  • Middle Aged
  • Prognosis
  • Statistics, Nonparametric
  • Time Factors
  • Ventricular Outflow Obstruction / etiology
  • Ventricular Outflow Obstruction / pathology*