Diagnosis of Latent Hypertrophic Obstructive Cardiomyopathy with Dobutamine Stress Echocardiography

ABSTRACT

BACKGROUND: In latent type of hypertrophic obstructive cardiomyopathy, there is no pressure gradient at rest in left ventricular outflow tract(LVOT), but it develops with provocation. Dobutamine increase myocardial contractility and may inducce outflow tract obstruction. To evaluate the usefulness of dobutamine induced outflow tract obstruction as a provocation test, nine patients with latent obstructive cardiomyopathy were studied. METHOD: 680 cases of dobutamine stress echocardiography were reviewed. Nine patients developed late peaking outflow velocity pattern in response to dobutamine infusion(inducible group). Ten patients developed early peaking velocity pattern were included as control group. Left ventricular dimension, outflow tract diameter were measured, and pattern of septal hypertrophy was classified. Changes of peak velocity and acceleration time/ejection time ratio (AT/ET) were measured at rest and peak dose dobutamine. RESULTS: The peak outflow velocity at rest was not different in both groups(1.49±0.45, 1.18±0.11m/sec). Peak velocity and AT/ET ratio were significantly increased in inducible group(4.2±0.9m/sec, 0.66±0.17), but no significant changes were noted in control group. Patients with inducible group had greater septal thickness, smaller outflow tract diameter and greater prevalence of septal bulge morphology. CONCLUSION: These results suggest that dobutamine stress Doppler echocardiography could be a useful provocation test to diagnosis of latent obstructive cardiogyopathy.