[Validation of the three-dimensional method of sestamibi gated-SPECT in the calculation of the left ventricular ejection fraction in patients with ischemic heart disease. Comparison with contrast ventriculography].
INTRODUCTION AND OBJECTIVE: Tomography with acquisition synchronized with electrocardiography, gated-tomography, allows the assessment of left ventricular contractile function. The accuracy of a new method of gated-tomography, based on the three dimensional representation of the left ventricle to calculate the ejection fraction was validated by means of comparison with contrast ventriculography. METHODS: We studied 85 patients with ischemic cardiopathy, and ejection fraction was calculated by contrast ventriculography and sestamibi-gated-tomography, at rest and throughout 10 micrograms/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 ventriculography in the calculation of ejection fraction, both with acquisition at rest (r = 0.80) and throughout Dobutamine (r = 0.82). The average underestimation of gated-tomography calculation of ejection fraction was significantly greater for the rest study (-0.12 [IC 95% 0.04, -0.30]) than the dobutamine study (-0.07 [IC 95% 0.09, -0.24]). Patients with greater perfusion defects (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 assesses 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-tomography in the calculation of ejection fraction.