The relationship of left atrial volume and left atrial pressure in patients with hypertrophic cardiomyopathy: an echocardiographic and cardiac catheterization study.

BACKGROUND: Left atrial enlargement is a marker of diastolic dysfunction, which is present in most patients with hypertrophic cardiomyopathy (HCM). It is unclear as to whether left atrial volume is a reliable measure of ventricular filling pressures in these patients.
METHODS: Left atrial volume index (LAVI) was measured in 100 symptomatic patients with HCM using transthoracic echocardiography, followed by cardiac catheterization with transseptal measurement of left atrial pressure (LAP) and end-diastolic pressure within 48 hours.
RESULTS: LAVI was only modestly related to mean LAP (r=0.24, P=.02), and there was no significant relation to end-diastolic pressure (r=0.11, P=.28). The specificity of increased LAVI (>28 cm3/m2) for elevated LAP (>15 mm Hg) was poor (16%). However, all patients with normal LAVI had normal LAP.
CONCLUSIONS: Although left atrial size may reflect chronic changes due to diastolic dysfunction in HCM, the relation of increased LAVI to ventricular filling pressures is modest. Nonetheless, a normal LAVI suggests normal ventricular filling pressures in patients with HCM.