Gated SPECT: What’s the ideal method to measure LVEF?

Among the variables that characterize mechanical cardiac performance, left ventricular ejection fraction (LVEF) has attracted broad clinical interest, as various studies have provided ample evidence that LVEF is a major prognostic parameter [1–4]. Also, LVEF is among the selection criteria for device-based anti-arrhythmic or resynchronization therapy [5, 6]. Several imaging techniques allow for the assessment of LVEF, e.g., 2D and 3D echocardiography, gated SPECT, contrast angiography, cardiovascular magnetic resonance imaging (CMR) and computed tomography [7]). In patients with suspected ischemia, a common strategic sequence in which imaging techniques are being utilized is echocardiography, gated SPECT and coronary angiography, the latter frequently combined with or followed by intervention. As these three imaging techniques may all yield LVEF values it is not uncommon in clinical practice to have access to multiple LVEF measurements of the same patient. If, in one patient, these three LVEF values are available, what would be the measure of preference? The answer to this question depends upon the reliability of the measurement technique and on its proven prognostic value. Whether or not the echocardiogram, gated SPECT and the ventriculogram determined during angiography faithfully assess LVEF depends on a large variety of factors: the build of the patient, the technical quality of the equipment, amount of views (monoplane/biplane), quality of the analyzing software/algorithms, the potential for quantitative analysis, and of the operator/analyst being the most important ones [8–13]. Comparison with CMR, an important reference technique often being considered as a gold standard [14–19], can help in getting an impression of the relative accuracy of LVEF as measured by echocardiography, gated SPECT and contrast ventriculography [20–22].