A New Method for Quantification of Left Ventricular Systolic Function Using a Corrected Ejection Fraction

OBJECTIVES: Left ventricular ejection fraction (EF) is a suboptimal measure of ventricular function. Recent mathematical modelling of left ventricular contraction has shown that the EF is determined by both myocardial shortening (strain) and by end-diastolic wall thickness. Increasing end-diastolic wall thickness resulted in augmented radial wall thickening. This may result in a significant ‘overestimation’ of ventricular systolic function as assessed by the EF. This study proposes a new measure of ventricular systolic function, the corrected EF (EF(c)) to allow for the presence of concentric left ventricular hypertrophy (LVH).

METHODS: The study uses a new two-layer, three-dimensional mathematical model of ventricular contraction. Changes in end-diastolic wall thickness in addition to long-axis and mid-wall circumferential strain were modelled.

RESULTS: Iso-strain lines were obtained where myocardial shortening (strain) is constant; EF increases with increasing end-diastolic wall thickness. The corrected EF is determined by following the iso-strain lines to the equivalent EF in the absence of hypertrophy (e.g. 9 mm thickness). For example, an individual with a mean end-diastolic wall thickness of 20 mm and measured EF of 60% has a corrected EF (EF(c)) of 37%.

CONCLUSIONS: The study shows that the EF is determined by absolute wall thickening and provides a nomogram for comparing EF when LVH is present. The EF(c) is a potential new measure of left ventricular systolic function. Its possible role will need validating in mortality trials. 

PMID: 21216767

Posted in Echo and tagged , , , , , , .

One Comment

  1. This is an interesting idea! It sounds complicated, but what the authors are showing is that as your wall thickness increases, your strain goes down, even though your LVEF is ok. This is why cardiac amyloid patients can have normal LVEFs but still have heart failure symptoms.

    Usually investigators have focused on measuring diastolic filling. These authors incorporating a diastolic measure (diastolic wall thickness) with systolic measures (strain, LVEF) to come up with a new measure that will detect abnormal function in “diastolic” diseases.

    These points reflect to two things. 1). People really want a simple measure of measuring dysfunction in diastole. Recently on this site there was a post about a Radiogrpahics paper reviewing MRI of diastolic function () Looking over that paper it struck me how many diastolic parameters there are and how little they really add. If you could find a really simple, useful parameter for diseases of “diastole” it would be helpful. (Notice that this paper assumes that diseases of “diastole” also have a component of systolic dysfunction even though LVEF is normal).

    The second point is this: 2). MRI is really well suited for this. Look at what’s being measured here: Wall thickness. Mass. So even though this is an echo paper, I think in the end, this line of investigation will lead to an MRI application.

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