Biological factors and overestimation of left ventricular ejection fraction by gated SPECT

BACKGROUND: Some patients present an overestimated left ventricular ejection fraction (LVEF) on electrocardiogram-gated myocardial scintigraphy (gated SPECT). OBJECTIVE: To establish the relationship between biological factors and overestimated LVEF. METHODS: We selected 3838 patients who underwent gated SPECT between May 20, 2000 and September 16, 2005 with normal perfusion images and LVEF >50%. The following variables were analyzed: gender (29.4% females and 70.6% males), age (from 20 to 94 years – mean: 56 years), weight (from 33.5 to 150 kg – mean: 79.6 kg), height (from 138 to 220 cm – mean: 171 cm) and BMI (from 13.9 to 54 – mean: 27.2). In a subgroup of 1002 patients who underwent echocardiogram, the diastolic diameter (from 36 to 68 mm – mean 47.5 mm) and systolic diameter (from 22 to 41 mm – mean 29.8 mm) variables were included. The patients were divided into two groups: normal LVEF (80%). The odds ratio (OR) for presenting an overestimated LVEF was calculated for each variable using logistic regression. RESULTS: The following odds ratios were found (p 0.2). In the subgroup of 1002 patients, a statistically significant influence was found in overestimated LVEF values for the systolic diameter, gender and height variables. CONCLUSION: Although systolic diameter influences the overestimation of LVEF, the gender and height variables have an independent influence on LVEF overestimation by gated SPECT.