Echo and heart failure: when do people need an echo, and when do they need natriuretic peptides?

Abstract

Heart failure (HF) is a threat to public health. Heterogeneities in aetiology and phenotype complicate the diagnosis and management of HF. This is especially true when considering HF with preserved ejection fraction (HFpEF), which makes up 50% of HF cases. Natriuretic peptides may aid in establishing a working diagnosis in patients suspected of HF, but echocardiography remains the optimal choice for diagnosing HF. Echocardiography provides important prognostic information in both HF with reduced ejection fraction (HFrEF) and HFpEF. Traditionally, emphasis has been put on the left ventricular ejection fraction (LVEF). LVEF is useful for both diagnosis and prognosis in HFrEF. However, echocardiography offers more than this single parameter of systolic function, and for optimal risk assessment in HFrEF, an echocardiogram evaluating systolic, diastolic, left atrial and right ventricular function is beneficial. In this assessment echocardiographic modalities such as global longitudinal strain (GLS) by 2D speckle-tracking may be useful. LVEF offers little value in HFpEF and is neither helpful for diagnosis nor prognosis. Diastolic function quantified by E/e' and systolic function determined by GLS offer prognostic insight in HFpEF. In HFpEF, other parameters of cardiac performance such as left atrial and right ventricular function evaluated by echocardiography also contribute with prognostic information. Hence, it is important to consider the entire echocardiogram and not focus solely on systolic function. Future research should focus on combining echocardiographic parameters into risk prediction models to adopt a more personalized approach to prognosis instead of identifying yet another echocardiographic biomarker.

Keywords: 2D echocardiography; 2D speckle-tracking echocardiography; heart failure; mechanics.

Figure 1

This figure shows the law of Laplace applied to a cross-sectional diagram of LV. The law of Laplace dictates that the LV wall tension is directly proportional to the product of the LV pressure and the LV radius. The LV wall tension is also inversely proportional to the LV wall thickness. LV, left ventricle.

Figure 2

A risk stratification tree obtained by CART analysis. A CART analysis includes many echocardiographic parameters to determine the most important predictors of mortality in HFrEF patients. The analysis selected LVEF, GLS, peak early diastolic filling velocity (E) and TAPSE as the most important predictors of mortality in HFrEF and combined them into a binary risk assessment scheme. CART, classification and regression tree analysis; GLS, global longitudinal strain; HF, heart failure; HFrEF, HF with reduced ejection fraction; LVEF, left ventricular ejection fraction; TAPSE, tricuspid annular plane systolic excursion. Reprinted from JACC: Cardiovascular Imaging, Vol 8, Sengeløv M, Jørgensen PG, Jensen JS, Bruun NE, Olsen FJ, Fritz-Hansen T, Nochioka K & Biering-Sørensen T, Global longitudinal strain is a superior predictor of all-cause mortality in heart failure with reduced ejection fraction, Pages 1351–1359, Copyright (2015), with permission from Elsevier .

Figure 3

This figure depicts the myocardial fibre orientation of the left ventricular wall and their directions of contraction. In the subepicardium, myocardial fibres are oriented in a left-handed helix, while they run in a right-handed helix in the subendocardium. The cardiac midwall comprises circumferentially oriented fibres. (A) In the normal heart, the subepicardial left-handed helical fibres are balanced by the subendocardial right-handed helical fibres and longitudinal function is normal. (B) The subendocardial fibres are most susceptible to dysfunction from hypertension, increasing age, diabetes and other cardiovascular risk factors. When subendocardial function is lost, longitudinal contraction is impaired and the subepicardial fibres are left unbalanced. This results in decreased GLS and exaggerated circumferential contraction and GCS. This pattern of contraction is common in the presence of cardiovascular risk factors such as hypertension, increasing age and diabetes. GLS, global longitudinal strain; GCS, global circumferential strain. Adapted, under the terms of the original Creative Commons Attribution licence, from Nakatani 2011 (113).

Figure 4

A model of progressive abnormalities in left ventricular function in heart failure across LVEF spectrum. Subclinical myocardial dysfunction triggered by cardiovascular risk factors such as age, hypertension and diabetes may present as depressed longitudinal deformation and decreased GLS but increased circumferential deformation and GCS. Progression is characterized by continuous impairment in longitudinal deformation. LVEF decreases at a point when circumferential function also starts to decline. GLS, global longitudinal strain; GCS, global circumferential strain; LVEF, LV ejection fraction; HFpEF, heart failure with preserved ejection fraction; HFrEF, heart failure with reduced ejection fraction.