MEASUREMENT OF LEFT-VENTRICULAR MASS IN HYPERTROPHIC CARDIOMYOPATHY USING MRI - COMPARISON WITH ECHOCARDIOGRAPHY

Left ventricular mass (LVM) is an important consideration in the manag ement of cardiac hypertrophy associated with hypertrophic cardiomyopat hy (HCM), systemic hypertension, and other diseases. A brief MRI cardi ac imaging procedure used to monitor regression of LVM during treatmen t would be beneficial in management of these patients, since echocardi ograms cannot be obtained in all patients and since the volume of a hy pertrophic heart can straightforwardly be assessed from a series of to mographic slices. The present study was designed to evaluate a brief c ardiac MRI procedure for measurement of LVM in HCM and compare it to e chocardiography. MRI images acquired in a simulated transverse body pl ane were used to evaluate the mass of the left ventricle in 6 ex vivo human hearts obtained at autopsy. The estimates of LVM by MRI in the e x-vivo hearts were within 8% of the actual LVM. MRI images were acquir ed to evaluate LVM in 5 normal subjects and 12 patients diagnosed with HCM. Echocardiography was accomplished on 4 of the normal subjects an d 10 of the patients having HCM. There were no significant differences in LVM by MRI and echocardiographic techniques in normal subjects. Tr ansverse MRI images acquired on normal subjects demonstrated that esti mates of LVM are reproducible when repeated over 3-w to 3-mo intervals . Images selected for analysis represented the heart in an early diast olic phase. MRI and echocardiographic techniques demonstrated signific ant differences in LVM in HCM patients. Estimates of LVM in normal sub jects and patients diagnosed with HCM were normalized for body weight. The LVM estimates for HCM patients were very significantly different than normal subjects. A short (20 min) in vivo cardiac MRI exam acquir ed in the transverse body plane can be used to accurately measure LVM. Normalized estimates of LVM may be a useful index for monitoring the progression or regression of LVM in HCM and hypertension and following aortic valve replacement for aortic stenosis.