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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 33  |  Issue : 3  |  Page : 835-842

Assessment of left atrial function in patients with heart failure: correlation with brain natriuretic peptide levels


1 Department of Cardiovascular Medicine, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Cardiovascular Medicine, National Military Hospital, Alexandria, Egypt

Date of Submission29-Oct-2018
Date of Decision04-Nov-2018
Date of Acceptance10-Nov-2018
Date of Web Publication30-Sep-2020

Correspondence Address:
Mohamed L. H. Moustafa
National Military Hospital, Alexandria
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_348_18

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  Abstract 


Objectives
To assess left atrial function by speckle tracking in patients with heart failure (HF) with reduced ejection fraction and HF with preserved ejection fraction and correlate it with brain natriuretic peptide (BNP).
Background
HF is a clinical syndrome characterized by impaired structure and/or function of the heart, leading to dyspnea and fatigue at rest or with exertion. The pathophysiology of HF is complex, and there is no single etiological lesion.
Patients and methods
The study comprised 80 randomly selected persons presented to Cardiology Department of Menoufia University Hospitals, Egypt, from January to October 2016 to April 2018. They included 35 patients with Ejection fraction (EF) less than 50% Heart failure with reduced ejection fraction (HFrEF) (group I), 35 patients with Ejection fraction (EF) more than 50% Heart failure with preserved ejection fraction (HFpEF) (group II), and 10 normal individuals (control group), with typical signs and symptoms of HF and normal sinus rhythm.
Results
Patients with HF with reduced EF had significant increase in left ventricular volumes and left atrium (LA)volumes when compared with controls. All HF patients with reduced EF had a significant decrease in LA active emptying (volume, fraction)and LA passive emptying fraction, volume) when compared with controls. BNP had significantly higher values in HF patients with reduced EF compared with controls.
Conclusion
LA increased (volumes) and decreased (function), measured by strain and volumetric parameters in HF patients with reduced ejection fraction regarding controls. There was a significant increase in BNP in patients with HF with reduced ejection fraction and those with preserved ejection fraction compared with controls. The current study showed that BNP level was higher among HF groups (groups I and II) than among the controls (group III).

Keywords: brain natriuretic peptide, heart failure, left atrium, speckle tracking echocardiography, strain


How to cite this article:
Al-Noamany MF, Sultan GM, Dawood AA, Sebaeia NF, Moustafa ML. Assessment of left atrial function in patients with heart failure: correlation with brain natriuretic peptide levels. Menoufia Med J 2020;33:835-42

How to cite this URL:
Al-Noamany MF, Sultan GM, Dawood AA, Sebaeia NF, Moustafa ML. Assessment of left atrial function in patients with heart failure: correlation with brain natriuretic peptide levels. Menoufia Med J [serial online] 2020 [cited 2020 Oct 28];33:835-42. Available from: http://www.mmj.eg.net/text.asp?2020/33/3/835/296668




  Introduction Top


Congestive heart failure (HF) is a complex clinical syndrome that can result from a functional or structural cardiac disorder that impairs ventricle's ability to fill with or eject blood. As there is no definitive diagnosis for HF, it remains a clinical diagnosis that is largely based on careful history and physical examination and supported by ancillary tests, such as chest radiograph, electrocardiography, and echocardiography [1].

Atrial function, in close interdependence with left ventricular (LV) function, plays a key role in maintaining an optimal cardiac performance. The left atrium (LA) modulates LV filling through its reservoir, conduit, and booster pump function, whereas LV function influences LA function throughout the cardiac cycle. The LA can act to increase LA pressure (in significant atrial disease) and can react to increased LV filling pressure (in significant ventricular disease). LA remodeling is related to LV remodeling, and LA function has a central role in maintaining optimal cardiac output despite impaired LV relaxation and reduced LV compliance [2].

Strain is a measure of tissue deformation and is defined as the change in length normalized to the original length. The rate at which this change occurs is called strain rate [Figure 1]. Deformation in a one-dimensional object, such as a thin bar, is limited to lengthening or shortening [3]. Strain and strain rates are either tissue Doppler imaging based or speckle tracking echocardiography (STE) based [4].{Figure 1}

STE is a new noninvasive ultrasound imaging technique that allows for an objective and quantitative evaluation of global and regional myocardial function independently from the angle of insonation and from cardiac translational movements [5].

Although STE technique was introduced for the exclusive analysis of LV function, several studies have recently extended its applicability to other cardiac chambers, such as the LA [6]. The atrial longitudinal strain, deriving from application of the analysis of myocardial deformation using STE at atrial chambers, is considered the first parameter useful for functional analysis of the LA, and it presents considerable feasibility and reproducibility [7].

Aim of the work

The aim was to assess the left atrial function by speckle tracking in patients with HFrEF and HFpEF and correlated it with brain natriuretic peptide (BNP).


  Patients and Methods Top


All participants gave written informed consent before inclusion into the study. They comprised 80 randomly selected persons who were presented to Cardiology Department at Menoufia University hospitals, Egypt, during the period of 10 months from January 2012 to October 2016. They included 35 patients (HFrEF) with EF more than 50% (group I), 35 patients (HFpEF) with EF more than 50% (group II) and 10 normal individuals (control group), with typical signs and symptoms of HF and normal sinus rhythm.

Conventional transthoracic echocardiography was done using a 1.7–4 MHz transducer (GE Vivid 9 Ultrasound Machine) (Ultrasound Supply, Diagnostx, LLC 5735 Benjamin Center Dr. Tampa, FL, 33634 USA): an M-Mode tracing to detect aortic and left atrial dimensions, interventricular septum thickness, LV posterior wall thickness, LV end-diastolic diameter, the LV end systolic diameter, fractional shortening, and LVEF. Continuous and pulsed wave Doppler echocardiography on mitral valve: transmitral Doppler flow velocity was obtained from apical four-chamber view, and peak early filling velocity (E) and peak atrial velocity (A) were recorded. E/A ratio was calculated. Two-dimensional echocardiography was done to assess LA volumes at end of systole (max AV), at end of diastole (min AV), and preceding atrial contraction (V pre-A) in both apical four-chamber and apical two-chamber views. Volumetric assessment of LA function was calculated by the following formulae in apical four-chamber and two-chamber views.

LA total emptying volume (LAEV): max AV-min AV; LA total emptying fraction (LAEF): max AV-min AV/max AV; LA passive emptying volume (LApEV): max AV–V pre-A; LA passive emptying fraction (LApEF): (max AV–V pre-A)/max AV; LA active emptying volume (LAAEV): V pre-A–min AV; and LA active emptying fraction (LAAEF): (V pre-A–min AV)/V pre-A [8].

Speckle tracking echocardiography

Apical four-chamber, two-chamber, and three-chamber views are obtained using conventional two-dimensional gray-scale echocardiography, during breath hold with a stable ECG recording. Two-dimensional sector width is adjusted to include LV and LA. Three consecutive cardiac cycles are recorded and averaged. The frame rate is set between 60 and 80 frames per second. LA endocardial surface is manually traced in both four-chamber and two-chamber views by a point-and-click approach. An epicardial surface tracing is then automatically generated by the system. After manual tracing, the software automatically divides each wall into three (apical, mid, and basal) segments. LA strain at the end of LV systole [peak atrial longitudinal strain (PALS)], LA strain with LA contraction [peak atrial contraction strain (PACS)] and postatrial contraction (post-A) were was calculated as average of three segments of each wall (apical, middle, and basal). LA contraction systolic index (CSI) in each LA wall by PALS/PACS ×100 formula [9].

BNP is measured using an ELISA kit by Chongqing Biospes Co. Ltd, (Jiulongpo District, Chongqing, China), which is based on standard sandwich enzyme-linked immunosorbent assay technology. The purified anti-BNP antibody is precoated onto 96-well plates, and then HRP-conjugated anti-BNP antibody is used as detection antibodies. TMB substrates (A and B) are used to visualize HRP enzymatic reaction catalyzed by HRP. If the color changes from blue into yellow, it will be considered positive, with density of yellow proportional to the BNP amount of sample captured in the plate. The produced blue color product is changed into yellow by adding acidic stop solution. The density of yellow is proportional to the BNP amount of sample captured in plate. Read the absorbance at 450 nm in a microplate reader, and then the concentration of BNP can be calculated [10].

Statistical analysis

All data were collected, tabulated, and statistically analyzed using SPSS, 19.0 for Windows (SPSS Inc., Chicago, Illinois, USA) and MedCalc 13 for Windows (MedCalc Software BVBA, Ostend, Belgium). The following statistics are used:

  1. Descriptive: for example, mean and SD
  2. Analytical: Student's t test and Mann–Whitney test with the level of significance of P value. P value less than 0.05 = significant, P value less than 0.001 = highly significant, and P value more than 0.05 = nonsignificant [11].



  Results Top


There was no statistical significant difference regarding age (52.2 ± 6.0) in group I, (51.6 ± 54) in group II, and (50.5 ± 6.0) in group III), with P value less than 0.001; hypertension (60, 60, and 20%, respectively), with P value 0.059; and diabetes mellitus (60, 54.3, and 0%, respectively), with P value 0.003 [Table 1].
Table 1: Comparison between the three studied groups according to demographic data, diabetes mellitus, and hypertension

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The mean value of BNP was higher among the case groups (491.48 ± 374.04 in groups I and 111.99 ± 20.76 group II) than among the control one (48.95 ± 25.39 in group III). It was higher among group I than among group II, and this difference was statistically highly significant (P < 0.001). Regarding volumetric measurements of LA, there was a highly significant increase in LA volumes (Max AV, Min AV, and Pre-A) in both apical four-chamber and apical two-chamber views in patients with HF when compared with the corresponding values of the control group. In apical two-chamber view, a significant decrease in LAEF, LApEF, and LA AEF in patients when compared with the controls, with no statistically significant decrease in LAEV, LApEV, and LAAEV in patients when compared with the controls. Comparing the three groups regarding longitudinal peak systolic strain demonstrated a stepwise decrease of cumulative peak systolic strain of the anterior wall, inferior wall, lateral wall, septal wall, posterior wall, anteroseptal wall, and global LV strain from group III (control) to group II to group I. When matching group I with group III (control), there was a highly significant reduction of the mean value of global LV strain as well as cumulative longitudinal peak systolic strain of septal, lateral, inferior, and posterior walls (P 3 < 0.001). Moreover, a significant difference was found between the two groups regarding the mean value of cumulative longitudinal peak systolic strain of anterior and anteroseptal walls (P 3 < 0.05). Comparing group II with group III (control), there was a highly significant reduction of the mean value of cumulative longitudinal peak systolic strain of septal and posterior walls (P 2 < 0.001). Moreover, a significant difference was found between the two groups regarding the mean value of global LV strain and cumulative longitudinal peak systolic strain of the inferior wall (P 2 < 0.05). On the contrary, the difference between the two groups regarding cumulative longitudinal peak systolic strain of the anterior, lateral, and anteroseptal walls did not reach a statistical significance. When matching group II with group I, there was a significant reduction of the mean value of global LV strain as well as cumulative longitudinal peak systolic strain of septal, lateral, and anterior walls (P 1 < 0.05) [Table 2].
Table 2: Comparison between the three studied groups according to body surface area, brain natriuretic peptide and left atrium and left ventricular systolic strain rates

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When comparing group III (control) with group I regarding peak systolic LV longitudinal strain of all analyzed myocardial segments, there was a highly significant difference in the mean value of peak systolic strain of mid and apical segments of septal, lateral, and posterior walls (P 3 < 0.001). Moreover, there was a significant difference of the mean value of peak systolic strain in middle and apical segments of inferior wall as well as in basal and middle segments of anterior and anteroseptal walls (P 3 < 0.05). When comparing group III (control) with group II, there was a significant reduction of the mean value of peak systolic strain of mid and apical segments of lateral and posterior walls (P 2 < 0.05). When matching group II with group I, there was a significant reduction of the mean value of peak systolic strain of apical segments of septal, inferior, and posterior walls as well as basal and mid segments of lateral and basal posterior walls (P l < 0.05). Regarding peak systolic strain rate (SRs s −1) in the three groups, there was a stepwise reduction of cumulative peak systolic strain rate of the anterior, inferior, lateral, septal, posterior, and anteroseptal walls and global LV strain rate from group III (control) to group II to group I. Comparing group III with group I, a significant reduction of the mean value of cumulative peak SRs s −1 of global LV, lateral, inferior, and posterior walls was seen (P 3 < 0.05) [Table 3].
Table 3: Comparison between the three studied groups according to εsys %

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Comparing group II with group I, a significant reduction of the mean value of cumulative peak SRs s −1 of lateral and inferior walls and global LV was seen (P 1 < 0.05). There was a significant decrease in LVGS and strain rate parameters (Srls, SrlA, and SrLA) in patient groups when compared with the corresponding values of the control group, and a significant decrease in LVGS and strain rate parameters (Srls, SrlA, and SrLA) in patient groups when compared with the corresponding values of the control group. Comparison between the study groups regarding cumulative LV early diastolic strain rate (SRe s −1) demonstrated a stepwise reduction of the mean value of cumulative SRe s −1 of the anterior, inferior, lateral, septal, posterior, and anteroseptal walls and global LV from group III to group II to group I. When matching group III with group I, there was a highly significant reduction of the mean value of cumulative SRe s −1 of the septal, inferior, and anterior walls and global LV (P 3 < 0.001). In addition, there was a significant reduction of the mean value of cumulative SRe s −1 of the lateral, posterior, and anteroseptal walls (P 3 < 0.05). When comparing group III with group II, there was a significant reduction of the mean value of SRe s −1 of posterior and anteroseptal walls and global LV (P 2 < 0.05). When matching group II with group I, a highly significant reduction of the mean value of cumulative SRe s −1 of septal and inferior walls was seen (P 1 < 0.001). Moreover, there was a significant reduction of the mean value of cumulative SRe s −1 of lateral and anterior walls global LV (P 1 < 0.05). When matching group III with group I, there was a highly significant reduction of the mean value of cumulative SRa s −1 of the inferior and anteroseptal walls and global LV (P 3 < 0.001). In addition, there was a significant reduction of the mean value of cumulative SRa s −1 of the septal, lateral, anterior, and posterior walls (P 3 < 0.05). On comparing group III with group II, there was a highly significant reduction of the mean value of cumulative SRa s −1 of inferior, anterior, and anteroseptal walls and global LV (P 2 < 0.001). In addition, there was a significant reduction of the mean value of cumulative SRa s −1 of the septal, lateral, and posterior walls and global LV (P 2 < 0.05). There was a significant difference between patients with HF and controls [Table 4].
Table 4: Comparison between the three studied groups according to mean of εsys%, left ventricular global (early strain rate diastolic), and left ventricular global (SRa diastolic)

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  Discussion Top


The atria perform three different functions during the various phases of the cardiac cycle, that is, serving as reservoir during systole, passive conduit during early diastole, and booster function during late diastole [12].

The study includes 35 patients (HFrEF) with EF less than 50% (group I), 35 patients (HFpEF) with EF more than 50% (group II), and 10 controls of age and sex matched to group III.

In the present study, it was observed that patients with HFrEF had significantly increased LV dimensions and volumes, with P value less than 0.001 compared with the corresponding values of the control group. In patients with HFrEF, LV dysfunction causes increased amounts of blood in ventricles, thereby increasing both LVEDV and LVESV, which in turn increase LV end-diastolic pressure. Chronically stressed LV leads to increase in the LV wall tension causing remodeling and hypertrophy of the LV, which lastly dilates [13].

Moreover, in the present investigation, it was observed that patients with HFrEF had significant increase in LA diameter and LA volumes when compared with the control group.

This can be explained by the fact that during diastole, except for the period encompassing isovolumic relaxation, the LA chamber is exposed directly to LV diastolic pressure (which is high in HF patients) through opening of mitral valve. Because of its thin-walled structure, the LA tends to dilate with increasing pressure [14]. Abnormally dilated LA emerges as a compensatory response complying with increase left atrial volumes which aids in preservation of cardiac output in patients with HF [15].

Same results were obtained by Kurt et al. [16] who reported that patients with EF less than 50%, DHF, and patients with normal EF and LV hypertrophy but not in HF have increased in LA volumes.

Concerning LA reservoir function, in this study, it was observed that there was a highly significant decrease in LA reservoir function (P < 0.001) measured by volumetric parameters in patients with HFrEF when compared with the corresponding values in the control group.

Regarding strain parameters, there was a highly significant decrease in LA reservoir function (P < 0.001), when measured by strain in patients with HFrEF compared with the corresponding values of the control group. This was evident by decrease in the PALS in patient group in all atrial walls.

In patients with HFrEF, the LA is exposed to high LV-filling pressures, thus the LA pressure rises to maintain adequate LV filling, and the rise in wall tension contributes to its dilatation. However, gradual increase in LA dimension disturbs frank-starling relationship, with decrease in atrial compliance and increase in LA stiffness with decrease in LA reservoir function [15].

Russo et al. [17] demonstrated that LV longitudinal strain as a measurement of LV systolic function was the strongest predictor of LA reservoir function owing to its strong correlation with LAEV and LAEF.

Concerning LA conduit function, volumetric assessment showed highly significant reduction of LApEV and LApEF in apical four-chamber view, with P value less than 0.001, in the patient group when compared with the corresponding values of the control group.

This can be explained by decrease in the LV filling rate early in congestive HF patients owing to elevated LV end-diastolic pressures that reduce the early diastolic left atrial – LV pressure gradient and thus decreasing conduit function [18].

Same results were obtained by Bilen et al. [19] who demonstrated impaired LA conduit function assessed by volumetric parameters in HprEF or HFrEF.

Concerning left atrial systolic function, regarding volumetric assessment of LA pump function, the present investigation showed a significant reduction in LAAEF in patients with HF when compared with the corresponding values of the control group in both apical four-chamber and apical two-chamber views, whereas there was no significant difference between patients and control in LAAEV in both apical four-chamber and apical two-chamber views.

Concerning strain parameters, there was a highly significant decrease in LA strain parameters, namely, PACS, post-A in all atrial walls (septal, lateral, anterior, and inferior walls) when compared with the corresponding values of control group, whereas there was a significant increase in LA contraction systolic index (CSI) in patients with HFrEF compared with the controls. However, when comparing atrial transmitral flow velocity (A), there was no significant difference between patients and control.

It is likely that intrinsic problems with LA myocardial contractility as LA ischemia or fibrosis play a role [20], and may be also mediated by increased work load imposed on the left atrial myocardium owing to increased LV diastolic stress, which, overtime, may lead to intrinsic left atrial dysfunction and gradual decrease in LA contribution in LV filling [21].

Similar results were obtained by Kurt et al. [16] who demonstrated that there was a decrease in LA systolic function measured by strain and strain rate and volumetric parameters in HFrEF or HFpEF.

Regarding BNP level, the current study showed that BNP level was higher among HF groups (groups II, II) than among controls (group III). Moreover, the mean value of BNP was higher among group III (with (HFrEF) than among group II.

In the present study, there was a significant decrease in LV global strain and LV strain rate parameters including SrLs, SrLE, and SrLA, with P value less than 0.001, in patient group when compared with the corresponding values of the control group.

Regarding correlation between LA function assessed by volumetric measurements and NYHA class, only three parameters of LA function showed negative correlation with NYHA class, with none of them being statistically significant, whereas all parameters of LA (reservoir and systolic) function assessed by strain showed negative correlation with NYHA class, with the severity of HF symptoms increases with the severity of LA dysfunction.


  Conclusion Top


Patients with HFrEF had increase in LA diameter and volumes (LA maximum, minimum, and pre-A). There is decreased LA reservoir, conduit, and systolic function in patients with HF compared with the controls. The severity of HF symptoms positively correlated with the LA strain parameters. The current study showed that BNP level was higher among HF groups (groups I and II) than controls (group III).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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