LVEF is regarded as an essential measure of LV systolic function, even though mathematical reasoning and early experimental work have shown it is load-dependent.
LVEF is not an intrinsic contractility parameter Another recently published analysis of a very large clinical dataset (403, 977 echocardiograms from 203, 135 unique patients), emphasizes the presumably “physiological” range of 60–65%, which is associated with best survival it also suggests the existence of a supra-normal LVEF phenotype associated with reduced survival. Large population studies show a Gaussian distribution of LVEF, with a mean value around 62% (measured by echo or CT), which is probably ideal. The observation was not further investigated however, given the recognized circadian changes in all other hemodynamic determinants of cardiac performance, it is to be regarded as noteworthy. A small study in the 1990s identified a temporary (up to 30 min) dramatic decrease of scintigraphy-measured LVEF at waking up in the morning, to as low as < 30% in some normal subjects. There is also evidence for circadian and sleep-induced LVEF changes. Athletes express lower rest EF values (52.9% ± 5.86% compared to non-athletic controls 58.2% ± 6.05%, P < 0.001), but with more significant ΔLVEF increase of 16.5% ± 8.51% during exercise and with greater LV contractility reserve vs. 65% ± 0.3% ).Ī fourth issue involves the physiologic variations of LVEF.ĭuring exercise, increased LVEF was demonstrated. LVEF was also shown to increase with age, with significant difference between the extreme age groups, more pronounced in females (as demonstrated in one large population study 62% ± 0.5% vs. A very large echocardiographic study in more than 8, 000 healthy volunteers < 70 years suggested ethnic-specific cutoffs for EF normal ranges. CMR data showed that women have higher LVEF than men in the general population, with higher SV for a given EDV, independent of known potential confounders (low LVEF defined as below the 2.5th percentile of a healthy subset was 61% in women and 55% in men) current guideline recommendations describe separate cutoffs. Third, there are recognized age, gender, and ethnicity differences. This led Fonarow and Hsu to question the paradigm and suggest that LVEF of 50% to 55% should not be considered within the “normal” range. Asymptomatic left ventricular systolic dysfunction defined as LVEF 55%. Second, abnormal LVEF values were clearly defined below 50% the dismal prognostic value of abnormal LVEF was observed in several cohorts. , observed in a 2014 analysis that the reference values are based on studies involving cohorts as low as 60 patients ranging up to 1, 200, suggesting that further validation studies are required. ĭefining the normal range of values is an overlooked issue in clinical practice.įirst of all, the aforementioned differences in methodology and algorithms between diagnostic modalities make unlikely a fixed value. The same applies for radionuclide techniques: in a large community study, Single-Photon Emission Computed Tomography (SPECT) did not correctly discern between the left atrium and LV, yet the sensitivity and specificity for determining LVEFs of < 40% were 90% and 86%, respectively. There is generally good agreement between methods, as described in Table 1, even though the same studies showed that LV volumes tend to be smaller when compared to CMR imaging and had significant variability. On the other hand, improvement of endocardial border delineation with contrast 2D echocardiography has been shown to derive more reproducible values, more similar to cardiac magnetic resonance (CMR). These issues have led to the development of less geometrical methods and techniques which rely on good border delineation, including three-dimensional (3D) echocardiography or computer tomography (CT). Two-dimensional (2D) echocardiographic calculation of the LVEF using the recommended Simpson method of disks is easy to perform, using widely available echo machines nonetheless accuracy suffers from image quality. mode M derived LVEF or the area-length method). Most experts calculate LV volumes based on the geometrical approximation of the normal ellipsoid shape of the LV, which becomes a source for error when LV remodeling in the context of eccentric hypertrophy (i.e. Each technique has its draw-backs and sources of error, and there are differences in methodologies and algorithms. LVEF calculation is possible using invasive angiographic methods (which used to be considered the gold standard) or by widely available non-invasive imaging.
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