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ORIGINAL ARTICLE
Year : 2015  |  Volume : 28  |  Issue : 2  |  Page : 532-539

Assessment of left atrial function in patients with systolic heart failure: strain imaging study


Department of Cardiology, Faculty of Medicine, Menoufia University, Menoufia, Egypt

Date of Submission07-Oct-2013
Date of Acceptance19-Jan-2014
Date of Web Publication31-Aug-2015

Correspondence Address:
Rania S Abd El-Ghani
Department of Cardiology, Faculty of Medicine, Menoufia University, BadeaKhairy Street, Al Nozha, Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.163914

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  Abstract 

Objectives
The aim of this work was to assess the left atrial function by speckle tracking in patients with systolic heart failure.
Background
Heart failure 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 heart failure is complex and there is no single lesion. The left atrial function contributes toward left ventricular filling by means of its three components: a reservoir component; a passive conduit component; and a pump component, with active contraction. Changes in atrial function during the different phases of the cardiac cycle can be assessed noninvasively by the new 2D strain, derived from speckle tracking, that allows us to identify these three components of atrial function.
Materials and methods
This study included 50 randomly selected individuals: 30 with systolic heart failure and ejection fraction (EF) less than 50% (patient group) and 20 normal individuals (control group). Left ventricle (LV) volumes were measured. Left atrium (LA) volumes were measured at the end of systole, LA maximum volume (Max AV), at the end of diastole, LA minimum volume (Min AV), and preceding atrial contraction (VPre-A). LA total emptying volume (LAEV), LA total emptying fraction(LAEF), LA passive emptying volume (LApEV), LA passive emptying fraction (LApEF), LA active emptying volume (LAAEV), and LA active emptying fraction (LAAEF) were calculated in both apical four-chamber and apical two-chamber views. Peak atrial longitudinal strain, peak atrial contraction strain, and LA strain at the end of LA contraction (Post-A) were measured. The LA contraction systolic index was calculated. LV global strain was measured in apical four-chamber, two-chamber and three-chamber views. LV strain rate was determined, and the LV peak systolic, early diastolic, and late diastolic strain rate were measured.
Results
Patients with systolic heart failure showed a significant increase in LV volumes and LA volumes (Max AV, Min AV, and VPre-A volumes) compared with the control group. A significant decrease in LA peak atrial longitudinal strain, peak atrial contraction strain, Post-A, and LA contraction systolic index was observed in patients with systolic heart failure (P < 0.001). Also, there was a decrease in LAEV, LAEF, LApEV, LApEF, LAAEV, and LAAEF in patients with systolic heart failure compared with the control group.
Conclusion
Increased LA volumes and decreased LA function were measured by strain and volumetric parameters in patients with systolic heart failure compared with controls.

Keywords: heart failure, left atrium, speckle-tracking echocardiography, strain


How to cite this article:
Reda AA, Soliman MA, Ahmed MK, Abd El-Ghani RS. Assessment of left atrial function in patients with systolic heart failure: strain imaging study. Menoufia Med J 2015;28:532-9

How to cite this URL:
Reda AA, Soliman MA, Ahmed MK, Abd El-Ghani RS. Assessment of left atrial function in patients with systolic heart failure: strain imaging study. Menoufia Med J [serial online] 2015 [cited 2020 Apr 6];28:532-9. Available from: http://www.mmj.eg.net/text.asp?2015/28/2/532/163914


  Introduction Top


Congestive heart failure is a complex clinical syndrome that can result from functional or structural cardiac disorder that impairs the ventricle's ability to fill with or eject blood. As there is no definitive diagnosis for heart failure (HF), it remains a clinical diagnosis that is largely based on a careful assessment of history and physical examination and supported by ancillary tests such as chest radiograph, ECG, 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 plays 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 the 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 rate are either tissue doppler imaging based or speckle-tracking echocardiography (STE) based [4] .

Speckle-tracking echocardiography 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 the 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] .
Figure 1: Strain measures tissue deformation and is defi ned as the change in the dimension or the length (L1−L0) normalized to the initial length (L0) of the region of interest

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Figure 2: LA strain by 2D speckle-tracking echocardiography. LA, left atrium; PACS, peak atrial contraction strain; PALS, peak atrial longitudinal strain [9]

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Figure 3: LV global strain curve [10]. LV, left ventricle

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Figure 4: Longitudinal strain rate image obtained from the apical two-chamber view [10]

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  Materials and methods Top


The study included 50 randomly selected individuals who presented to the cardiology department at Menoufia University hospitals, Egypt, during the period of 10 months from January 2012 to October 2012. They included 30 patients with systolic HF, EF less than 50%, and the New York Heart Association (NHYA) ranging from Iclass II to IV (patient group), and 20 normal individuals (control group).

Inclusion criteria

  1. Patients with systolic HF EF less than 50%.
  2. Typical symptoms and signs of HF.
  3. Clinical HF according to the NYHA ranged from class II to IV.
  4. Normal sinus rhythm.


Exclusion criteria

  1. Any rhythm other than a normal sinus rhythm.
  2. Valvular heart disease.
  3. Congenital heart disease.
  4. Pericardial disease.
  5. Patients with a poor echogenic window such as obese patients or patients with chronic obstructive pulmonary disease (COPD).
  6. Patients with renal or liver cell failure.
Conventional transthoracic echocardiography was performed using a 1.7-4 MHz transducer (GE Vivid 9 Ultrasound Machine, GE Healthcare, NY, USA): an M-Mode tracing to detect aortic and left atrial dimensions, interventricular septum thickness, LV posterior wall thickness, LV end diastolic diameter, and the LV end systolic diameter, fractional shortening, and LVEF. Continuous and pulsed wave Doppler echocardiography on the mitral valve: transmitral Doppler flow velocity was obtained from the apical four-chamber view and peak early filling velocity (E) and peak atrial velocity (A) were recorded. The E/A ratio was calculated. Two-dimensional echocardiography was performed to assess LA volumes at the end of systole (Max AV), at the end of diastole (Min AV), and preceding atrial contraction (VPre-A) in both apical four-chamber and apical two-chamber views. Volumetric assessment of LA function was performed using the following formulae in apical four-chamber and two-chamber views [8] .

  1. LA total emptying volume (LAEV): Max AV-Min AV.
  2. LA total emptying fraction (LAEF): Max AV-Min AV/Max AV.
  3. LA passive emptying volume (LApEV): Max AV-Vpre-A.
  4. LA passive emptying fraction (LApEF): (Max AV-Vpre-A)/Max AV.
  5. LA active emptying volume (LAAEV): Vpre-A-Min AV.
  6. LA active emptying fraction (LAAEF): (Vpre-A-Min AV)/Vpre-A.
STE: Apical four-chamber, two-chamber, and three-chamber views are obtained using conventional 2-D grayscale 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 /s. LA endocardial surface is traced manually in both four-chamber and two-chamber views using 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 calculated as the average of three segments of each wall (apical, mid, and basal) [Figure 2]. LA contraction systolic index (CSI) in each LA wall was calculated using the (PALS/PACS) × 100 formula [9] .

To obtain LV global strain (GS) we do measurements at three points at the LV, apex, and annular hinge points in apical four-chamber, three-chamber, and two-chamber views and allow the system to process the data. After finishing tracing and auto processing of the three views, the GS and Bull's eye report will be obtained. Strain is the peak negative value obtained at or before aortic valve closure [Figure 3]. The segmental strain rate was analyzed in apical four-chamber, two-chamber, and three-chamber views in the 18-segment model of the LV, that is three segments per wall (apical, mid, and basal segments). Three parameters were obtained from each view: peak longitudinal systolic Sr (SrLs), peak early diastolic Sr (SrLE), and peak late diastolic Sr (SrLA) [Figure 4].

Statistical analysis

  1. Descriptive: Mean and SD.
  2. Analytical: Student's t-test, Mann-Whitney test, with the level of significance of P value as follows: P < 0.05 = significant, P < 0.001 = highly significant, and P > 0.05 = nonsignificant [11]

  Results Top


The study population was divided into two groups: systolic HF group (N = 30), which included patients with EF less than 50% and NYHA class ranging from II to IV, and a control group (N = 20).

In terms of conventional echocardiographic parameters, there was a highly significant increase in LA diameter, LV end diastolic diameter, LV end systolic diameter, end diastolic volume, and end systolic volume in patients with HF compared with the corresponding values of the control group. Also, there was a significant decrease in LV posterior wall diameter systole, fractional shortening, EF, E, and E/A ratio values in patients with HF compared with the controls.[Table 1] Also, there was a significant increase in LA volumes (Max LA, Min AV, and Pre-A) in patients with HF compared with the control group [Table 2].
Table 1 Conventional echocardiographic doppler parameters in controls and heart failure patients

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Table 2 Volumetric parameters of LA in patients with heart failure and controls

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In the assessment of LA function by volumetric measurements and strain, in the apical four-chamber view, there was a highly significant decrease (P < 0.001) in LAEV, LAEF, LApEV, LApEF, and LAAEF in patients with HF compared with the corresponding values of the controls, whereas there was no significant difference between patients and controls in LAAEV. In the apical two-chamber view, there was a significant decrease (P < 0.05) in LAEF, LApEF, and LAAEF in patients compared with the controls, whereas there was no significant difference in LAEV, LApEV, and LAAEV between patients and controls.[Table 3] Also, the study showed a significant decrease in PALS, PACS, and Post-A in all LA walls in patients with HF compared with the corresponding values of the control group, whereas there was a significant increase in LA CSI in patients with HF compared with the controls [Table 4].

In the present study, there was a significant decrease in LV GS and strain rate parameters (SrLs, SrLA, and SrLA) in the patient group compared with the corresponding values of the control group [Table 5].
Table 3 Assessment of left atrial function by volumetric echocardiography in patients with heart failure and controls

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Table 4 Strain parameters of LA walls in heart failure in patients with heart failure and controls

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Table 5 Comparison between LV global strain and strain rate parameter in patients with heart failure and controls

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There was a nonstatistically significant correlation between LAEF, LAPEV, LAPEF, and NYHA class. There was a positive correlation between LAEV, LAAEV, LAAEF, and NYHA class, There was a statistically significant correlation (P < 0.05) between LAAEV and NYHA class. There was a significant positive correlation between NYHA and LAAEV in patients with systolic HF [Table 6].
Table 6 Correlation between LA function measured by conventional echocardiography and NYHA class in patients with heart failure

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There was a negative correlation between all LA parameters measured by strain (PALS, PACS, Post-A, and LA CSI) in septal, lateral, anterior, and inferior walls, and NYH class. A statistically significant correlation (P < 0.05) was found between PALS of LA lateral, anterior, inferior walls, and NYHA. [Figure 2] shows a significant negative correlation between PALS of the lateral atrial wall and NYHA class [Table 7].
Table 7 Correlation between LA function measured by strain and NYHA class in patients with heart failure

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  Discussion Top


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

The study included thirty patients with EF less than 50% who had clinical HF according to the NYHA that ranged from class II to IV (patient group) and 20 controls age and sex matched to group 1.

Conventional echocardiographic parameters

In the present study, it was observed that patients with systolic HF had significantly increased LV dimensions, and volumes, with P value less than 0.001, compared with the corresponding values of the control group. [Table 1] In patients with systolic HF, LV dysfunction causes increased amounts of blood in ventricles, thus increasing both LV end diastolic volume and LV end systolic volume, which in turn increase LV end diastolic pressure. Chronically stressed LV leads to an increase in the LV wall tension, causing remodeling and hypertrophy of the LV, which finally dilates [13] .

Also, in the present investigation, it was observed that patients with systolic HF showed a significant increase in LA diameter [Table 1] and LA volumes [Table 2] 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 the 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 an increase in left atrial volumes that aids in the preservation of cardiac output in patients with HF [15] .

The 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 HF, have increased LA volumes.

Left atrial function in patients with systolic heart failure

Concerning LA reservoir function

In this study, it was observed that there was a highly significant decrease in the LA reservoir function (P < 0.001) measured by volumetric parameters in patients with systolic HF compared with the corresponding values in the control group [Table 3].

In terms of strain parameters, there was a highly significant decrease in the LA reservoir function (P < 0.001) when measured by strain in patients with systolic HF compared with the corresponding values of the control group. This was evident by a decrease in the PALS in the patient group in all atrial walls [Table 4].

In patients with systolic HF, the LA is exposed to high LV filling pressures; thus, the LA pressure increase to maintain adequate LV filling and the increase in wall tension contributes toward its dilatation. However, a gradual increase in LA dimensions disturb the frank-starling relationship, decreases atrial compliance, and increases LA stiffness, with a decrease in the LA reservoir function [15] .

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

LA conduit function

Volumetric assessment showed a highly significant reduction in LApEV and LApEF in the apical four-chamber view (P<0.001) in the patient group compared with the corresponding values of the control group [Table 3].

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

The same results were obtained by Bilen et al. [19] , who reported impaired LA conduit function assessed by volumetric parameters in HF patients with preserved or reduced ejection fractions.

Left atrial systolic function

In terms of the volumetric assessment of LA pump function, the present investigation showed a significant reduction in LAAEF in HF patients 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 controls in LAAEV in both apical four-chamber and apical two-chamber views [Table 3].

In terms of 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) compared with the corresponding values of the control group, whereas there was a significant increase in LA CSI in patients with systolic HF compared with the controls [Table 4]. However, on comparing atrial transmitral flow velocity (A), there was no significant difference between the patients and the controls [Table 1].

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

Similar results were obtained by Kurt et al.[16] , who reported that there was a decrease in LA systolic function measured by strain, strain rate, and volumetric parameters in HF patient groups with reduced or preserved ejection fractions.

In the present study, there was a significant decrease in LVGS and LV strain rate parameters including SrLs, SrLE, and SrLA with P value less than 0.001 in the patient group compared with the corresponding values of the control group [Table 5].

Correlation between LA function assessed by volumetric measurements and NYHA class

Only three parameters of LA function showed a negative correlation with NYHA class, with none of them statistically significant [Table 6], whereas all parameters of LA (reservoir and systolic) function assessed by strain showed a negative correlation with NYHA class; the severity of HF symptoms increases with the severity of LA dysfunction [Table 7].

The LA plays an important role in maintaining LV filling and consequently LV stroke volume, especially when the LV is dysfunctional [2] . The enlargement of the LA and the increase in the LA emptying fraction are adaptive responses to impaired LV diastolic function to maintain normal LV filling pressures. Decreased LA compliance with reduced reservoir and contractile pump functions can counteract this adaptive mechanism and promote the occurrence of symptoms [22] . Bilen et al. [19] reported a significant negative correlation between NYHA and LA reservoir and pump functions (LAEF and LAAEF), but no significant correlation with conduit function.


  Conclusion Top


Patients with systolic HF showed increased LA diameter and volumes (LA maximum, minimum, and Pre-A). There was a significant decrease in the LA strain parameters, namely, PALS, PACS, and Post-A in HF patients with reduced LV ejection fraction compared with the controls. Decreased LA reservoir, conduit, and systolic function were observed in patients with HF compared with the controls. The severity of HF symptoms correlated positively with the LA strain parameters.


  Acknowledgements Top


Conflicts of interest

There are no conflicts of interest.

 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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