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Variability in LVEF by Cardiac Imaging Modality
Study Questions:
What is the intermodality variability of left ventricular ejection fraction (LVEF) measured by echocardiography, gated single-photon emission computed tomography (SPECT), and cardiovascular magnetic resonance (CMR) in patients with LV dysfunction?
Methods:
The investigators conducted an international multicenter diagnostic study with LVEF imaging performed at 127 clinical sites in 26 countries from July 24, 2002, to May 5, 2007, and measured by core laboratories. This was a secondary study of clinical diagnostic measurements of LVEF in STICH (Surgical Treatment for Ischemic Heart Failure), a randomized trial to identify the optimal treatment strategy for patients with LVEF of ≤35% and coronary artery disease. Data analysis was conducted from March 19, 2016, to May 29, 2018. At baseline, most patients had an echocardiogram and subsets of patients underwent SPECT and/or CMR. LVEF was measured by a core laboratory for each modality independent of the results of other modalities, and measurements were compared among imaging methods using correlation, Bland-Altman plots, and coverage probability methods. Association of LVEF by each method and death was assessed. Finally, the prognostic effect of the different measures of LVEF for association with all-cause mortality was assessed using Cox regression models.
Results:
A total of 2,032 patients (mean [standard deviation] age, 60.9 [9.6] years; 1,759 [86.6%] male) with baseline LVEF data were included. Correlation of LVEF between modalities was r = 0.601 (for biplane echocardiography and SPECT [n = 385]), r = 0.493 (for biplane echocardiography and CMR [n = 204]), and r = 0.660 (for CMR and SPECT [n = 134]). Bland-Altman plots showed only moderate agreement in LVEF measurements from all three core laboratories, with no substantial overestimation or underestimation of LVEF by any modality. The percentage of observations that fell within a range of 5% ranged from 43% to 54% between different imaging modalities.
Conclusions:
The authors concluded that there was substantial variation between modalities in LVEF determination by core laboratories.
Perspective:
This study reports that there is substantial variability in LVEF measurement using different modalities, even when assessed by core laboratories. In fact, the variability in LVEF measurement exceeded 5% in about half of the patients. It appears that longitudinal assessments of a given patient may best be accomplished using a single imaging modality. Furthermore, variability in LVEF assessment by different imaging modalities should be considered in trial design and clinical management. Considering this variability in LVEF measurement, rigid cut points in LVEF may not be the best basis for clinical decision making.
Clinical Topics: Heart Failure and Cardiomyopathies, Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), Acute Heart Failure, Computed Tomography, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Nuclear Imaging
Keywords: Coronary Artery Disease, Diagnostic Imaging, Echocardiography, Heart Failure, Magnetic Resonance Imaging, Myocardial Ischemia, Stroke Volume, Tomography, Emission-Computed, Single-Photon, Ventricular Dysfunction, Left
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