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Left ventricular outflow tract gradient variability in hypertrophic cardiomyopathy.
Jeffrey B Geske1, Paul Sorajja, Steve R Ommen
1Division of Internal Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
Clinical Cardiology
|July 18, 2009
Summary
Left ventricular outflow tract (LVOT) obstruction in hypertrophic cardiomyopathy (HCM) varies significantly day-to-day. This variability impacts clinical decisions for managing HCM patients with LVOT obstruction.
Area of Science:
- Cardiology
- Cardiovascular Medicine
- Medical Diagnostics
Background:
- Symptomatic hypertrophic cardiomyopathy (HCM) management relies on assessing left ventricular outflow tract (LVOT) obstruction.
- The dynamic nature of LVOT obstruction, influenced by ventricular load and contractility, is known but its day-to-day variability is underappreciated.
Purpose of the Study:
- To investigate the impact of LVOT gradient variability on clinical decision-making in hypertrophic cardiomyopathy patients.
- To quantify the day-to-day variability of LVOT obstruction measurements in HCM.
Main Methods:
- 100 hypertrophic cardiomyopathy patients underwent serial 2D Doppler transthoracic echocardiography and cardiac catheterization within 48 hours.
- Transseptal left-sided pressure measurements were obtained during catheterization.
- Simultaneous LVOT gradient measurements were performed in a subset of 15 patients to validate Doppler accuracy.
Main Results:
- LVOT gradients showed wide variability between methods, with 95% confidence limits of agreement of +/- 84 mm Hg.
- A significant 21% of patients were discrepantly classified regarding severe LVOT obstruction (>= 30 mm Hg) based on measurements.
- Simultaneous measurements confirmed high accuracy of Doppler, with 95% confidence limits of agreement +/- 12 mm Hg.
Conclusions:
- LVOT gradient measurements are crucial for characterizing obstruction severity in HCM.
- Marked day-to-day variability in LVOT obstruction exists in HCM patients.
- This variability must be carefully considered when determining therapeutic strategies for symptomatic HCM patients.
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