Validation of the three-dimensional method of sestamibi gated-spect for the calculation of the left ventricular ejection fraction in patients with coronary heart disease. Comparison with contrast ventriculography

Introduction and objective. Tomography with acquisition synchronized with e lectrocardiography, gated-tomography, allows the assessment of left ventric ular contractile function. The accuracy of a new method of gated-tomography , based on the three dimensional representation of the left ventricle to ca lculate the ejection fraction was validated by means of comparison with con trast ventriculography. Methods. We studied 85 patients with ischemic cardiopathy, and ejection fra ction was calculated by contrast ventriculography and sestamibi-gated-tomog raphy, at rest and throughout 10 mu g/kg/min of dobutamine. Furthermore, we assessed the extent of perfusion defect, as well as the number of segments with activity below 50% of the total 13 segments in which the tomographic slices were divided. Results. Gated-tomography was significantly correlated to contrast ventricu lography in the calculation of ejection fraction, both with acquisition at rest (r = 0.80) and throughout Dobutamine (r = 0.82). The average underesti mation of gated-tomography calculation of ejection fraction was significant ly greater for the rest study (-0.12 [IC 95% 0.04, - 0.30]) than the dobuta mine study (-0.07 [IC 95% 0.09, -0.24]). Patients with greater perfusion de fects (4 o more segments) had no differences in underestimation of ejection fraction (-0.13 [IC 95% 0.03, -0.30] versus -0.11 [IC 95% 0.07, -0.29]). Conclusions. The three-dimensional method of gated-tomography accurately as sesses the ejection fraction. The underestimation determined by this method was lower in the study done with viable doses of dobutamine. The extent of perfusion defect had no deleterious effect on gated-tomograpy in the calcu lation of ejection fraction.