|Year : 2020 | Volume
| Issue : 1 | Page : 295-302
Assessment of left atrial function in patients with ischemic and nonischemic dilated cardiomyopathy using speckle-tracking echocardiography
Abdalla M Kamal1, Naglaa F Ahmed1, Ahmed A Kamal2, Mohamed H Mostafa2
1 Department of Cardiology, Faculty of Medicine, Menoufia University, Menoufia, New Cairo, Egypt
2 Department of Cardiology, New Cairo Police Hospital, Police Academy, Ministry of Interior, New Cairo, Egypt
|Date of Submission||15-May-2018|
|Date of Decision||20-Jun-2018|
|Date of Acceptance||24-Jun-2018|
|Date of Web Publication||25-Mar-2020|
Mohamed H Mostafa
Menouf – Menoufia
Source of Support: None, Conflict of Interest: None
The aim was to assess left atrial (LA) function in patients with ischemic and nonischemic dilated cardiomyopathy using speckle tracking echocardiography.
LA changes occur in patients with dilated cardiomyopathy and LA enlargement is commonly found by echocardiography. Two-dimensional speckle tracking echocardiography is a tool for the evaluation of LA function.
Patients and methods
This casecontrol study was conducted on 67 randomly selected individuals who presented to the Cardiology Department of Faculty of Medicine, Menoufia University, Egypt, during the period from January 2017 to December 2017. They included 52 patients with systolic heart failure (HF) and 15 normal individuals. In this study, the LA maximum, minimum volumes, and volume before the atrial systole, and calculated total emptying, active emptying volumes, expansion index, and fraction were measured. Strains and strain rates during left ventricular (LV) systole and late LV diastole using speckle-tracking imaging were measured.
The study showed no significant differences between the nonischemic dilated cardiomyopathy (NIDCM) and ischemic dilated cardiomyopathy (IDCM) groups in the A peak, DT, septal e′, E/A, E/e′ and LAD, LVEDD. LA maximum volume (LAVmax) and the active emptying volume of LA (LAEV) showed no significant difference between the studied groups, but the total emptying capacity of the LA (LATV), the left atrial expansion index, and the left atrial active ejection fraction (LAAEF) were significantly lower in the NIDCM group. The LA strain and strain rate during LV systole (Ss, SRs) and during late LV diastole (Sa, SRa) representing the reservoir and booster pump function of the LA, respectively, were significantly lower in the NIDCM group.
LA systolic and late diastolic strains and strain rates were significantly lower in NIDCM patients. The LA dynamic reservoir and booster pump function were more severely impaired in NIDCM.
Keywords: cardiomyopathy, echocardiography, left atrium, speckle.tracking imaging, strain
|How to cite this article:|
Kamal AM, Ahmed NF, Kamal AA, Mostafa MH. Assessment of left atrial function in patients with ischemic and nonischemic dilated cardiomyopathy using speckle-tracking echocardiography. Menoufia Med J 2020;33:295-302
|How to cite this URL:|
Kamal AM, Ahmed NF, Kamal AA, Mostafa MH. Assessment of left atrial function in patients with ischemic and nonischemic dilated cardiomyopathy using speckle-tracking echocardiography. Menoufia Med J [serial online] 2020 [cited 2020 Mar 30];33:295-302. Available from: http://www.mmj.eg.net/text.asp?2020/33/1/295/281265
| Introduction|| |
Dilated cardiomyopathy (DCM) is a disease with high incidence and has a great social impact on patients. The main cause for the development of DCM is an ischemic heart disease, which is thought to be responsible for ventricular dilatation in more than 60% of cases of DCM. The diagnostic and therapeutic approaches to ischemic heart disease are well coded, thus allowing effective treatment of patients. On the other hand, the diagnostic and therapeutic strategies for nonischemic DCM are usually insufficient; in fact, the definition of 'nonischemic DCM' incorporates many different subforms with different etiology, clinical diagnosis, treatments, and outcomes, such as left ventricular noncompaction (LVNC), familial DCM, Takotsubo cardiomyopathy, postmyocarditis DCM, and peripartum cardiomyopathy,. Atrial function in a close interdependence with left ventricular (LV) function plays a key role in maintaining an optimal cardiac performance. The principal role of the left atrium (LA) is to modulate LV filling and cardiovascular performance by functioning as a reservoir for pulmonary venous return during ventricular systole, a conduit for pulmonary venous return during early ventricular diastole and a booster pump that augments ventricular filling during late ventricular diastole. It is important to recognize the interplay that exists among these atrial functions and ventricular performance throughout the cardiac cycle. For example, although the reservoir function is governed by atrial compliance during ventricular systole (and, to a lesser extent, by atrial contractility and relaxation), it is influenced by descent of the LV base during systole and by LV end-systolic volume. The LA structure and function assessment by echocardiography has gained interest lately and several quite recent studies have focused particularly on the LA and the changes it is submitted to in a wide range of pathologies. LA impairment has already been shown to emerge with advancing age,. Speckle-tracking echocardiography is a new noninvasive ultrasound imaging technique that allows for an objective and quantitative evaluation of global and regional myocardial functions independent of the angle of insonation and cardiac translational movements,,. 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. The atrial longitudinal strain, deriving from the application of the analysis of myocardial deformation using STE at atrial chambers is considered the first parameter useful for functional analysis of LA and it presents considerable feasibility and reproducibility.
The aim of this study was to assess the LA function in DCM patients of ischemic and nonischemic etiology using the speckle tracking echocardiography technique.
| Patients and Methods|| |
The study included 67 randomly selected individuals during the period of 8 months from January 2017 to October 2017. They included 52 patients with systolic HF, ejection fraction (EF) less than 50%, and the New York Heart Association (NHYA) ranging from class II to IV (patient group), and 15 normal individuals (control group). Among the 52 heart failure patients, 27 were diagnosed with IDCM (IDCM group), comprising 19 men and eight women. The remaining 25 patients were diagnosed with NIDCM (NIDCM group), comprising 15 men and 10 women. All participants provided an informed consent and the study protocol was approved by the Menoufia ethics committee.
Patients with systolic HF (EF <50%) with typical symptoms and signs of HF because of ICM or DCM according to the NYHA ranged from class II to IV and normal sinus rhythm were included. Patients with any rhythm other than a normal sinus rhythm, severe valvular lesions, congenital heart disease, recent acute coronary syndrome in the last 6 months, poor echogenic window, and patients with severe renal or liver cell failure were excluded. Every patient was subjected to a detailed personal and family medical history including age and sex of the patient, history of diabetes mellitus and hypertension, dyslipidemia, special habits such as smoking, drug history, family history of CAD, DCM, and SCD. All ICM patients reported a history of myocardial infarction. The DCM patients matched the diagnostic criteria established by the World Health Organization in 1996. The ECG results of all the subjects showed sinus rhythm.
A transthoracic echocardiography was performed using a GE Vivid E9 ultrasonographic unit (GE Healthcare, Wauwatosa, Wisconsin, USA) with an M5S probe (frequency 1.7–3.3 MHz) for echocardiography. Subjects assumed the left lateral decubitus position during the echocardiographic examination, and ECG was recorded simultaneously. They were instructed to breathe calmly and hold their breath when necessary to ensure image stability and clarity. B-mode images were acquired with a frame rate more than 60/s. Doppler measurements were performed with an insonation angle less than 60°. The LA diameter (LAD) and the LV end diastolic diameter (LVEDD) were measured on two-dimensional (2D) images. The LV ejection fraction (LVEF) was measured using the biplane Simpson method. Doppler was used to measure the early (E) and late (A) diastolic flow velocity through the mitral valve and their ratio (E/A), and the deceleration time (DT) of the E wave. By using apical four-chamber and two chamber views, the velocity of the septal mitral annulus at early diastole (e′) was obtained by tissue-Doppler imaging (TDI). The E/e′ ratio was used to estimate the filling pressures of the LV. 2D 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.
The LA volume was measured by the area length biplane method:
The maximum LA volume (LAVmax) appears in the last frame before mitral valve opening, whereas the minimum LA volume (LAVmin) occurs in the frame contiguous to mitral valve closure. The volume before LA contraction (LAVp) corresponds to the LA volume at the starting point of the P wave of the ECG. The volume indicators were corrected by body surface area:
The total emptying capacity of the LA (LATV)=LAVmax–LAVmin.
The left atrial expansion index (AEI) (LA total emptying fraction (LAEF) = (LAVmax–LAVmin)/LAVmin × 100%.
The active emptying volume of LA (LAEV) = LAVp–LAVmin.
The active ejection fraction (LAAEF) = (LAVp–LAVmin)/LAVp × 100%,.
Two-dimensional speckle tracking echocardiography of the left atrium
Apical four-chamber, two-chamber, and three chamber views are obtained using conventional 2D grayscale echocardiography, during breath-hold, with a stable ECG recording. The 2D sector width is adjusted to include LV and LA. The apical four-chamber view displays the atrial septum and lateral walls, and the two-chamber view shows the atrial anterior and inferior walls. The LA regions of interest were selected for analysis by the EchoPac 110.1.2 software (GE Healthcare, Chicago, Illinois, US). Three consecutive cardiac cycles are recorded and averaged. The frame rate is set between 60 and 90 frames/s. LA endocardial surface is traced manually in both four-chamber and two-chamber views using a point-and-click approach. The location of these acoustic markers shifted from frame to frame, representing tissue movement and providing spatial and temporal data for the calculation of velocity vectors. The software then automatically divided each view into six standard segments. A successful tracking of five segments or more was determined as acceptable. Continuous care was taken to keep the sample volume out of the pulmonary veins, LA appendage, and oval fossa,. Effective software tracking displays the strain and strain rate curves of each segment. The LA strain and strain rate during LV systole (Ss, SRs) and late LV diastole (Sa, SRa) were automatically provided by the software. The mean strain and strain rate were calculated for all atrial walls.
Two-dimensional speckle tracking echocardiography of the left ventricle
The strain measurements were performed offline with a dedicated automated software (Automated Function Imaging, EchoPAC PC, version 110.1.0; GE Healthcare). From each apical view [two-chamber view, four-chamber view, and three-chamber view (long-axis view)], three sample points were placed manually along the endocardium to define the LV base and the apex at the end-systolic frame. Each LV wall was divided into three segments (basal, median, and apical) and bull's eye according to the 17-segment classification was displayed. The values of longitudinal systolic strain of all the segments were averaged to obtain a 2D global longitudinal strain value. Basal, median, and apical strain values were, respectively, calculated as the average of the strain values of the six basal, six median, and four apical segments and the 17th segment was the apical cap and averaged from the 17 segments to provide the global longitudinal peak systolic strain (global longitudinal strain).
Statistical analysis was performed using the IBM SPSS Statistics for Windows, Version 19.0 (IBM Corp., Armonk, New York, USA). Quantitative data were presented as mean ± SD. The variables of the three groups were compared via completely randomized design analysis of variance. The results with significant differences were subjected to post-hoc analysis to compare the differences between the groups. Pearson's r test was used to compare the quantitative variables in the two study groups (NIDCM and IDCM).
A value of P less than 0.05 was considered statistically significant.
| Results|| |
With regard to basic echocardiographic parameters:
The A peak, deceleration time (DT), septal e′, fractional shortening (FS %), and LVEF (%) were lower in the NIDCM and IDCM groups than in the control group, and the E/A, E/e′ and LAD, LVEDD were higher in the NIDCM and IDCM groups than in the control group. However, there were no significant differences between the NIDCM and IDCM groups in the A peak, deceleration time (DT), septal e′, E/A, E/e′ and LAD, LVEDD [Table 1].
|Table 1: Clinical and basic echocardiographic data in the three study groups (control, nonischemic dilated cardiomyopathy, and ischemic dilated cardiomyopathy)|
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With regard to left atrial volume and function indexes:
LAVmax and LATV were higher in the NIDCM and IDCM groups, whereas AEI and LAAEF were lower than in the control group (P < 0.001). LAVmax and LAEV showed no significant difference between the NIDCM and IDCM group, but LATV, AEI, and LAAEF were significantly lower in the NIDCM group [Table 2].
|Table 2: Left atrial volume and function indexes in the three study groups (control, nonischemic dilated cardiomyopathy, and ischemic dilated cardiomyopathy)|
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With regard to left atrial strain and strain rate:
LA strain curves represent the physiology of atrial function and are closely related to LV mechanics during the cardiac cycle. During the reservoir phase, the LA is stretched as it is filled with blood from the pulmonary veins. In this phase, longitudinal LA strain increases (LA Ss), reaching a positive peak at the end of LA filling. This phase is also influenced by the downward movement of the mitral annulus toward the LV apex, as a result of LV contraction. Hence, LA strain during the reservoir phase reflects not only LA compliance but also LV longitudinal contraction. During the conduit phase, the LA empties and shortens quickly after mitral valve opening and LA strain decreases to a plateau, corresponding to LA diastasis. The LA wall subsequently shortens in a longitudinal direction during the LA contraction phase during late LV diastole. This movement leads to a further decrease in LA strain (LA Sa) and reflects the LA booster pump function.
Left atrial strain (LA Ss), left atrial strain rate (LA SRs) during LV systole, left atrial strain (LA Sa), and left atrial strain rate (LA SRa) during late LV diastole were lower in the NIDCM and IDCM groups than in the control group (P < 0.001). All systolic and late diastolic LA strains and strain rates were significantly lower in the NIDCM group than in the IDCM group [Table 3].
|Table 3: Left atrial (strain and strain rates) in the three study groups (control, nonischemic dilated cardiomyopathy, andischemic dilated cardiomyopathy)|
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Regarding correlations between LA deformation (LA strains and strain rates) and left atrial volume and function indexes [Table 4].
|Table 4: Correlations between left atrium deformation (left atrium strains and strain rates) and left atrial volume and function indexes in nonischemic dilated cardiomyopathy and ischemic dilated cardiomyopathy patients|
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In NIDCM patient groups, AEI showed a positive correlation with LA Ss (r = 0.974, P > 0.001), LA SRs (r = 0.947, P > 0.001), and LA Sa (r = 0.970, P > 0.001) and LAAEF also showed a positive correlation with LA Ss (r = 0.982, P > 0.001), LA SRs (r = 0.962, P > 0.001), and LA Sa (r = 0.980, P > 0.001) [Figure 1]. In IDCM patients group, AEI showed a positive correlation with LA Ss (r = 0.905, P > 0.001), LA SRs (r = 0.908, P > 0.001), and LA Sa (r = 0.868, P > 0.001) and LAAEF also showed a positive correlation with LA Ss (r = 0.943, P > 0.001), LA SRs (r = 0.949, P > 0.001), and LA Sa (r = 0.890, P > 0.001). So among all strains and strain rates, Ss, SRs, and Sa was positively correlated with AEI and LAAEF.
|Figure 1: Correlations between LA deformation (Ss, SRs, and Sa) and left atrial function indexes (AEI and LAAEF) in NIDCM patient groups. AEI, left atrial expansion index; LA, left atrium; LAAEF, left atrial active ejection fraction; NIDCM, nonischemic dilated cardiomyopathy; Sa, left atrial late diastolic strain; Ss, left atrial systolic strain; SRs, left atrial systolic strain rate.|
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| Discussion|| |
LA plays an important role in the cardiac cycle. It can store blood from the pulmonary veins in systole (reservoir function) and fill the LV during early diastole (conduit function). During the late diastole, the LA contract actively (booster pump function) and enhances the LV filling, which is essential at exercise.
In this study, we used 2DSTI to assess the structural and functional cardiac differences between NIDCM and IDCM patients and healthy controls. The major findings were as follows: (a) the systolic and late diastolic strains and strain rates were lower in NIDCM and IDCM patients than in controls; (b) although there were no significant differences in basic echocardiographic features between NIDCM and IDCM patients, all of the systolic and late diastolic strains and strain rates were significantly lower in NIDCM than in IDCM patients; (c) among all strains and strain rates, Ss, SRs, and Sa were positively correlated with AEI and LAAEF.
We found higher E/e′ and lower LVEF in patients than in controls, suggesting the LV diastolic and systolic functional damage in NIDCM and IDCM patients. In addition, the lower Ss, Sa, SRs, and SRa indicated that the dynamic reservoir and booster pump functions of LA were compromised in NIDCM and IDCM patients.
In previous studies, changes in LA function were detected by TDI. However, the TDI-derived strain and the strain rate measurement are restricted by angle dependence and only provide one-dimensional information.
Speckle tracking-derived 2D strain and strain rate measurement are angle independent and provide accurate information regarding the local and global strains. Inaba et al. showed that SRs, SRe, and SRa can reflect the LA reservoir, conduit, and booster pump function, respectively.
In the present study, strain and strain rate decreased significantly in both NIDCM and IDCM groups. The residual LV volume in the LV increases with load. If the LV compliance decreases, its filling pressure increases, which contributes to maintain the ejection volume (Frank-Starling law of the heart). Blood pressure remains high in the LA, which enlarges. The atrial wall is stretched, leading to the remodeling. Blood flow in the atrial wall arterioles is reduced, and myocardial damage may ensue, leading to chronic ischemia and fibrosis, resulting in compromised LA function.
In our study, we found no significant differences in basic echocardiographic variables, including the A peak, deceleration time (DT), septal e′, E/A, E/e′ and LAD, LVEDD between NIDCM and IDCM patients. Although load conditions and LA size were similar in both groups, LA strain and strain rate parameters such as Ss, Sa, SRs, and SRa were lower in NIDCM than in IDCM patients. The dynamic reservoir and booster pump functions of the LA were significantly lower in NIDCM than in IDCM patients.
These results were consistent with those reported by Triposkiadis et al. using 2D echocardiography, Moyssakis et al.. using stress echocardiography, and D'Andrea et al. using 2DSTI.
Thus, LA dynamic reservoir and systolic functions were decreased in NIDCM patients and were partially preserved in IDCM patients, despite similar loading conditions and LA sizes. Therefore, it is reasonable to assume that the depressed LA function in NIDCM patients is most likely the result of the LA involvement in the cardiomyopathy process.
This assumption is supported by previous findings of a higher degree of fibrotic LA change in DCM than in ICM patients. Sen et al. identified mechanistic differences in sarcoplasmic reticulum dysfunction in ICM and DCM patients.
In our study, the LAVmax was higher in NIDCM and IDCM patients, but both AEI and LAAEF were lower, representing changes in the dynamic reserve and booster pump function, respectively.
This might be explained by the following: (a) the AEI is closely related to LV systolic and diastolic functions and the mitral valve ring cannot move down effectively if LV contraction and active relaxation are impaired and (b) the LA booster pump function may compensate an early diastolic LV dysfunction (Frank–Starling mechanism).
The increased LV filling pressure leads to an elevation in LA pressure and decompensation as well as to an eventual reduction in LAAEF. LAVmax and LAEV were not significantly different between the NIDCM and IDCM groups, but AEI and LAAEF were lower in NIDCM patients even though they had similar LV systolic and diastolic functions and LA size. AEI and LAAEF are volume indexes that reflect the dynamic reservoir and booster pump function. Only a few of the routine parameters could reveal the differences between NIDCM and IDCM patients, whereas strains and strain rates always differed.
This study had some limitations. First, the size of the population sample was relatively small. Larger, multicentric studies should be completed to confirm our results. A second limitation was the analysis software, which was designed and validated for LV analysis, but not for the LA. In a limited number of studies, LA volume has been accurately quantified by three-dimensional echocardiography using both reconstructive and real-time techniques. STI can also be used to estimate deformation in three dimensions independent of the angle, providing additional information such as the longitudinal, circumferential, radial, and area strain.
| Conclusion|| |
The study showed no differences in basic echocardiographic features between NIDCM and IDCM patients. Only AEI and LAAEF were lower in NIDCM than in IDCM patients. However, the LA systolic and late diastolic strains and strain rates were significantly lower in DCM patients. The LA dynamic reservoir and booster pump function were more severely impaired in NIDCM than in IDCM patients. 2DSTI is a promising new method that could be used to evaluate these patients.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]