[Comparative study of left ventricular ejection fraction and volume by 2 isotopic methods and contrast angiography]

The tomographic mode has replaced the planar mode for radióisotopic studies of myocardial perfusion but not for the study of systolic ventricular function. The aim of this study was to compare monophotonic emission tomography (MPET), the planar mode (PM) and contrast angiography (Angio). The left ventricular volumes and ejection fractions were measured in 111 patients by the tomographic and planar modes and by biplane angiography in 70 of them. The MPET algorithm (QBS software) identified the ventricular endocardium in 96 of the 111 procedures (86%). The mean left ventricular ejection fractions (LVEF) were 57 +/- 17% (MPET, N = 96), 55 +/- 15% (PL, N = 96) and 57 +/- 15% (Angio, N = 70). There was a good correlation of LVEF between MPET and PL and MPET and Angio with negligible bias of 3 +/- 6% and 2 +/- 4% respectively and high correlation coefficients, r = 0.94 (MPET = 1.05*PL-0.2) and r = 0.93 (MPET = 1.1 x Angio-3). The differences between the 95% confidence intervals between MPET and PL and MPET and Angio may be explained by an overestimation of normal LVEF by MPET, especially in patients with low end systolic volumes. In these cases, the difference in LVEF by MEPT and the average LVEF from the 3 techniques was greater: 6 +/- 4% (< or = 20 ml) vs 0 +/- 3% (> 20 ml) (p < 0.0001). The authors conclude that, with the reserve that a high percentage of investigations could not be analysable. MPET seems to be a method of choice for assessing left ventricular systolic function.