ORIGINAL ARTICLE
Assessment of left ventricular function in systemic
lupus erythematosus patients by speckle tracking
echocardiography: Relation to circulating
endothelial progenitor cells
Sameh W.G. Bakhoum
a, Mohamed El Basel
b,*, Alshaimaa R. Alnaggar
b,
Mona S. Hamdy
c, Hanan Hussein
da
Cardiology Department, Faculty of Medicine, Cairo University, Egypt
b
Internal Medicine Department, Faculty of Medicine, Cairo University, Egypt
cClinical Pathology Department, Faculty of Medicine, Cairo University, Egypt d
Rheumatology Department, Faculty of Medicine, Cairo University, Egypt Received 5 May 2015; accepted 15 May 2015
Available online 10 June 2015
KEYWORDS Systemic lupus erythematosus;
Endothelial progenitor cells; Left ventricular function; Speckle tracking echocardiography
Abstract Background: Systemic lupus erythematosus is an autoimmune disease associated with reduced number and impaired function of endothelial progenitor cells (EPCs) responsible for vascular regeneration.
Aim of the work: to assess left ventricular (LV) function of SLE patients using relatively new speckle tracking echocardiography (STE) and examine the relation of any detected abnormalities with peripheral circulating EPC level.
Patients and methods: Fifty SLE patients and 25 healthy controls were subjected to quantifica-tion of peripheral circulating Cluster of differentiaquantifica-tion133+/vascular endothelial growth factor
receptor2+(CD133+/VEGFR2+) and CD34+/VEGFR2+EPCs, transthoracic echocardiography (TTE), tissue Doppler imaging (TDI) and STE.
Results: Patients showed a significantly lower CD133+/VEGFR2+ EPCs (p = 0.009) and CD34+/VEGFR2+EPC counts (p = 0.0001) compared to controls. TTE/TDI revealed a
signifi-cantly lower LV ejection fraction (EF) (p = 0.007), higher LV end systolic dimensions (p = 0.02), myocardial performance index (MPI) (p = 0.0001) and mitral flow E/lateral annulus E0 ratio (p = 0.002) in patients compared to controls. STE showed a significantly lower global
longitudinal strain (GLS) (p < 0.001), global circumferential strain (GCS) (p < 0.001) and global
* Corresponding author at: 10th El-Hekma Street, El-Mariottiah, Haram, Egypt. Tel.: +20 237624776, mobile: +20 1223616821. E-mail address:[email protected](M. El Basel). Peer review under responsibility of Egyptian Society of Rheumatic Diseases.
H O S T E D BY
Egyptian Society of Rheumatic Diseases
The Egyptian Rheumatologist
www.rheumatology.eg.net
www.elsevier.com/locate/ejr
http://dx.doi.org/10.1016/j.ejr.2015.05.002
1110-1164 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Egyptian Society of Rheumatic Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
strain rate during isovolumic relaxation period (GSRivr) (p = 0.01) in patients compared to
con-trols. By multiple logistic regression analysis, the independent variables affecting GCS and GSRivr were the prednisolone dose and the LVEF respectively. (95% CI =0.46 to 0.03;
p= 0.03 and 95% CI = 0.001–0.01; p = 0.021; respectively). There was no significant correlation of the GLS, GCS or GSRivrwith the EPCs.
Conclusion: STE detected subclinical systolic and diastolic abnormalities of LV function in SLE patients. These abnormalities of LV function did not show however any relation with the signifi-cantly lower EPC count detected in patients.
2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Egyptian Society of Rheumatic Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).
1. Introduction
Systemic lupus erythematosus (SLE) is an autoimmune disease associated with markedly increased atherosclerotic cardiovas-cular risk[1]. Young women with lupus are over 50 times more likely to have a myocardial infarction compared to a population-based sample of women of similar age [2]. Endothelial dysfunction was found to significantly contribute to this accelerated atherosclerotic process, independently of other classic risk factors of coronary artery disease (CAD) in SLE patients[3].
Anti-endothelial cell antibodies have been detected in autoimmune diseases and were found to induce endothelial cell (EC) apoptosis[4,5]. Endothelial progenitor cells (EPCs) rep-resent a heterogeneous group of cells released from the bone marrow into the circulation and are thought to contribute to vascular homeostasis and endothelial repair[6,7]. A study by Ebner et al.[8], demonstrated that circulating mature EPCs (CD34+/VEGFR2+) in the peripheral blood of SLE patients
are reduced in number, together with increased apoptosis, impaired differentiation and a reduced migratory capacity. The diminished number and the altered functionality of these mature EPCs reduce the ability to repair vascular damage. The number of EPCs was also found to be reduced, in heart failure (HF) irrespective of its etiology[9]. Several abnormali-ties of left ventricular (LV) systolic and diastolic function and increased LV mass have been described in SLE patients [10–12]. Whether the inherent endothelial dysfunction and the abnormalities of EPC mobilization in SLE contribute to this LV dysfunction is uncertain.
Speckle tracking echocardiography (STE) is a relatively new technique that provides accurate quantitative evaluation of regional and global LV function independent of the insona-tion angle and cardiac translainsona-tional movements [13]. The objective of this study was to detect subclinical LV dysfunction in SLE patients without clinically evident cardiovascular (CV) disease using STE and correlate possible LV function abnor-malities to circulating EPC count.
2. Patients and methods
In this prospective cross sectional study, a total of 50 SLE patients out of 75 patients screened for the inclusion and exclu-sion criteria were recruited from the outpatient clinic or the inpatient section of the Internal Medicine and Rheumatology and Rehabilitation Departments of Kasr Al-Ainy Cairo University Hospitals. They were enrolled in the study between
July and September 2013. Inclusion criteria were patients between 20 and 65 years of age with a diagnosis of SLE who fulfilled at least 4 of the updated revised criteria of the American College of Rheumatology for SLE diagnosis [14]. Exclusion criteria were patients with hypertension defined as a systolic blood pressure (BP)P 140 mmHg or diastolic BPP90 mmHg or on antihypertensive medication, diabetes mellitus defined as a fasting blood glucose P126 mg/dl or 2-h post-load glucose P200 mg/dl [15], history of smoking, or significant valvular heart disease. Twenty-five healthy age and gender matched subjects served as controls. The research protocol was approved by the ethics committee of Cairo University Hospital. The study was conducted in accordance with the Declaration of Helsinki. Written, informed consent was obtained from each patient.
The disease activity was assessed using the SLE disease activity index (SLEDAI) scoring system[16]. Information con-cerning disease duration and medications used was recorded. A blood sample was collected from all patients and controls for EPC count estimation in addition to routine laboratory workup including complete blood count, high sensitivity C-reactive protein (HsCRP) estimated by ELISA, erythrocyte sedimentation rate (ESR), renal function tests, total choles-terol and triglyceride levels, fasting blood glucose, anti-nuclear antibodies (ANA), and anti-double stranded deoxyri-bonucleic acid antibodies (Anti ds-DNA).
2.1. EPC identification and counting by flow cytometry (FC) analysis
Phycoerythrin (PE)-labeled monoclonal CD34 & anti-CD133 (Cat. No. 130-081-002; Miltenyi Biotec, Germany), fluorescein-labeled monoclonal anti-VEGFR2/KDR (Cat. No. FAB357F; R&D/UK) were used for the characterization of circulating EPCs. Isotype and fluorochrome-matched con-trol antibodies (Abs) (Mouse IgG1-FITC and IgG1-PE) were used for setting fluorescence markers around negative popula-tion and detecting non-antigen specific antibody binding. EDTA venous blood collected from patients and controls and kept at room temperature was analyzed within 24 h of venipuncture. For red blood cell lysis, peripheral blood sam-ples were diluted in 15 ml bicarbonate-buffered ammonium chloride solution for 15 min at room temperature. The cells were centrifuged and re-suspended in 2 ml FC staining buffer (Cat. No. FC001; R&D/UK). The number of cells was adjusted to 1· 106
cells/ml. The cells were then prepared into three test tubes, containing 100 ll of cell suspension each,
together with 10 ll FcR blocking reagent (to prevent non-specific binding) and 10 ll 7-AAD (to exclude dead cells from FC analysis). The first tube contained as well VEGFR2-Fluorescein and CD133/1-PE monoclonal Abs; the second tube contained as well VEGFR2-Fluorescein and CD34-PE monoclonal Abs while the third tube contained as well 10 ll of the matched isotypic control. Positive staining was defined as being greater than non-specific background staining. All samples were measured in duplicate. The lymphocyte fraction was identified on a forward/side scatter, and a minimum of 1· 105 lymphocytes were counted. Cells positive for
VEGFR2/CD133 were characterized as early EPCs, whereas cells positive for VEGFR2/CD34 within the lymphocyte frac-tion were characterized as mature EPCs. Results were expressed as the number of EPCs per 1· 106
lymphocytes. 3. Echocardiography
3.1. Transthoracic echocardiography (TTE) and tissue Doppler imaging (TDI)
TTE and TDI were performed to all patients and controls using a commercially available echocardiography machine
(ESAOTE MY LAB 60) equipped with broadband
S1-5 MHz transducer in the Cardiology Department of Kasr Al-Ainy Cairo University Hospitals. After a 10-min rest, sub-jects were examined in the left lateral decubitus position to obtain adequate images in different standard views. Left atrial, aortic diastolic, LV end-diastolic dimensions (LVEDD), and LV end-systolic dimensions (LVESD) were measured using M-mode echocardiography. Left ventricular ejection fraction (LVEF) was obtained by the biplane Simpson’s method. Trans-mitral pulsed wave Doppler velocities were recorded from the apical four-chamber (4-CH) view.
Early (E) and late (A) wave peak velocities, E/A ratio, E deceleration time (E-DT) were measured. By placing the Doppler sample volume midway between the mitral inflow and aortic outflow tract, trans-mitral and trans-aortic Doppler flows were recorded simultaneously. The ejection time (ET), isovolumic contraction time (ICT) and isovolumic relaxation time (IVRT) were measured and myocardial performance index (MPI) was calculated as the ratio: IVRT + IVCT/ET. The myocardial systolic (S), early diastolic (E0), and late diastolic (A0) peak velocities were obtained at the
lateral and septal corners of the mitral annulus in the 4-chamber (4-CH) view by pulsed wave tissue Doppler keeping the angle between the beam and the wall motion direction <15. The E/lateral annulus E0 (E/E0) ratio was subsequently
calculated. All the above measures were recorded as the aver-age of three consecutive cycles.
3.2. Speckle tracking echocardiography (STE)
Myocardial deformation measurements were obtained using STE. The analysis was performed on grayscale images of the LV obtained in the apical 4-CH, 2-chamber (2-CH) and short-axis mid-ventricular views. Three consecutive end-expiratory cardiac cycles using high frame rate >80 s1 harmonic imaging in each echocardiographic view were acquired. Data were analyzed off-line using dedicated software (ESAOTE MY LAB 60) on one cardiac cycle. The analysis is
initiated by defining manually in the apical views three endo-cardial landmarks at the lateral and medial corners of the mitral annulus and the LV cardiac apex and in the mid ventric-ular short axis views two landmarks at the inferior septum and the lateral wall. Manual adjustment of the segments of interest was performed when necessary. Thereafter, the software auto-matically analyzed different segments of interest. From the apical 4-CH view, longitudinal strain was assessed through basal, mid apical septal, basal, mid and apical lateral wall seg-ments. From the apical 2-CH view, longitudinal strain was assessed through basal, mid, apical inferior, basal, mid, and apical anterior wall segments. The global longitudinal strain (GLS) was calculated as the average of the LS of the 12 myocardial segments of the 4-CH and 2-CH views. From the short axis view at the level of the papillary muscles, the circum-ferential strain was assessed through the mid-segments of the anteroseptal, anterior, anterolateral, inferolateral, inferior, and inferoseptal walls. The global circumferential strain (GCS) was calculated as the average of the CS of the 6 mid myocardial segments of the ventricular short axis view. The global longitudinal systolic strain rate (GSSR), global diastolic strain rate during the IVR period (GSRivr), early diastole
(GSRe) and late diastole (GSRa) were calculated as the average
of the SR of the 12 myocardial segments of the 4-CH and the 2-CH views.
Statistical analysis: Normally distributed continuous variables were expressed as mean ± SD while continuous variables with non-normal distribution were presented as med-ian values and interquartile range (IQR). Categorical data were expressed as percentages. Differences between groups were assessed by unpaired 2-tailed t test and the Mann– Whitney U test for continuous variables, according to whether they were normally distributed or not. Categorical data and proportions were analyzed by the use of chi-square or Fisher’s exact test when required. Pearson and Spearman’s correlation were used to assess the correlation between differ-ent variables. Univariate and multivariate linear regression analyses were used to investigate possible associations between STE LV deformation abnormalities and other studied vari-ables. A significance level of p < 0.05 was used in all tests. All statistical procedures were carried out using SPSS version 15 for Windows (SPSS Inc., Chicago, IL, USA).
4. Results
A total of 50 SLE patients were included in the study; 47 females and 3 males. The median disease duration was 4.5 years with an IQR of 2–7.25 years. The mean SLEDAI score was 5.9 ± 5.75 (range: 0–20). All patients were receiving prednisolone with a median duration of 54 months (IQR: 24– 96 months). The median prednisolone dose was 7.5 mg (IQR: 5–15 mg). Twenty-five subjects with comparable age and gen-der were included. Patients had a significantly higher ESR (p < 0.001), HsCRP (p = 0.005), total serum cholesterol (p = 0.001), serum triglycerides (p = 0.001) and alanine transaminase (p = 0.01) compared to the control. The com-parison of the demographic and laboratory data between the patients and controls is shown inTable 1.
The CD133+/VEGFR2+ and CD34+/VEGFR2+ EPC counts were significantly lower in patients compared to controls (p = 0.009 and p = 0.0001, respectively). No significant
correlation was detected between CD133+/VEGFR2+ or CD34+/VEGFR2+EPC count and age of patients (r = 0.21,
p= 0.2 and r = 0.13; p = 0.4 respectively), disease duration (r =0.08, p = 0.6 and r = 0.01; p = 1 respectively), pred-nisolone dose (r = 0.02, p = 0.9 and r = 0.04; p = 0.8 respec-tively), prednisolone duration (r =0.05, p = 0.7 and r=0.03; p = 0.9 respectively), SLEDAI score (r = 0.19, p= 0.2 and r =0.23; p = 0.1 respectively), BMI (r = 0.03, p= 0.8 and r= 0.001; p= 1 respectively), Hs CRP (r = 0.26, p = 0.06 and r = 0.27; p = 0.06 respectively) or ESR (r = 0.17, p = 0.3 and r = 0.26; p = 0.07 respectively). 4.1. Echocardiographic data
4.1.1. M-mode, two-dimensional Doppler measurements The LVESD was significantly greater (p = 0.02) while the LVEF was significantly lower in patients (p = 0.007) com-pared to controls. Trans-mitral flow A wave velocity was sig-nificantly higher (p = 0.002) and the IVRT sigsig-nificantly prolonged (p = 0.01) in patients compared to controls. The MPI was also significantly higher in patients (p = 0.0001). 4.1.2. Tissue Doppler imaging (TDI) measurements
The medial and lateral mitral annulus E0wave velocities were
significantly lower in patients compared to controls (p = 0.002 and p = 0.01, respectively). The lateral E/lateral E0 ratio was
significantly higher in patients compared to controls
(p = 0.002). The detailed TTE and TDI measurements of the patients and controls are shown inTable 2.
4.1.3. Speckle tracking echocardiography (STE) measurements The GLS and GCS were significantly lower in patients com-pared to controls (p < 0.001 in both) (Fig. 1). The GSRivr was significantly lower in patients compared to controls (p = 0.01). The detailed STE measurements of patients and controls are listed in Table 3. Univariate logistic regression was used to investigate possible associations between the GLS, GCS, GSRivr and the following variables: age of
patients, duration of disease, prednisolone dose, prednisolone intake duration, use of azathioprine vs. cyclophosphamide, SLEDAI score, MPI, LVEF, CD133+/VEGFR2+EPC count and CD34+/VEGFR2+EPC count. There was no significant
correlation between any of the studied variables and GLS either by univariate or multivariate analysis. Using univariate analysis, there was no significant correlation between studied variables and GCS except for prednisolone dose. After adjust-ment for all variables using multiple logistic regression model, prednisolone dose remained the only independent variable affecting GCS (adjusted regression coefficient =0.24, 95% CI =0.46 to 0.03; p = 0.03). As regards GSRivr, LVEF
was the only variable affecting it by both univariate and multivariate logistic regression analyses (adjusted regression
Table 1 Demographic and laboratory data of systemic lupus erythematosus patients and controls.
Variable Patients (n = 50) Controls (n = 25) pvalue Demographic Age (years) 28.5 ± 8.5 30.2 ± 10.2 0.45 Female/male 47/3 23/2 1 BMI 26.5 ± 2.3 24.7 ± 1.9 0.001 Laboratory ESR (mm/h) 72.5 (35–110) 16 (11–24) <0.001 Hs CRP (mg/dl) 0.7 (0.31–1.52) 0.35 (0.23–0.79) 0.005 Hb (gm/dl) 10.3 ± 1.3 13.2 ± 1.5 0.001 WBCs (·103 /mm3) 7 ± 3.8 7 ± 2.4 0.9 Platelets (·103 /mm3) 234.7 ± 118.3 244.5 ± 105.9 0.7 Creatinine (mg/dl) 1 ± 0.4 0.9 ± 0.3 0.1 Albumin (g/dl) 3.7 ± 0.5 3.9 ± 0.9 0.09 Cholesterol (mg/dl) 210.1 ± 74.5 169.6 ± 26.7 0.001 Triglycerides (mg/dl) 163.2 ± 67.6 93.2 ± 21.6 0.001 AST (IU/l) 21.5 ± 7 19.2 ± 5.8 0.1 ALT (IU/l) 20.3 ± 6.1 16.5 ± 5.4 0.01 EPC (cells/106Ly)
CD133+/ VEGFR2+
5 (3–12) 109 (3–429) 0.009
CD34+/VEGFR2+ 3.5 (2–9) 63 (5–104) 0.0001 BMI: body mass index; ESR: erythrocyte sedimentation rate; Hs CRP: high sensitivity C-reactive protein; Hb: hemoglobin; WBC: white blood cells; AST: aspartate transaminase; ALT: alanine transaminase; VEGFR: vascular endothelial growth factor recep-tor; EPCs: endothelial progenitor cells. Ly: lymphocytes. Results are presented as mean ± SD or as median (Interquartile range). Bold figures mean significant p value.
Table 2 Transthoracic Echocardiography (TTE) and tissue Doppler imaging (TDI) data for the systemic lupus erythe-matosus patients and controls.
TTE measurements Patients (n = 50) Controls (n = 25) p value LVSWT (mm) 8.1 ± 1.8 7.9 ± 1.6 0.6 LVEDD (mm) 49.6 ± 6.4 47.3 ± 5.4 0.1 LVPWT (mm) 7.8 ± 1.5 7.7 ± 1.3 0.8 LVESD (mm) 33.0 ± 6.1 29.6 ± 5.6 0.02 EF (%) 64.0 ± 6.7 68.8 ± 7.7 0.007 Ao (mm) 25.2 ± 2.9 24.6 ± 2.9 0.4 LA (mm) 33.6 ± 5.5 31.3 ± 4.3 0.08 Transmitral velocity E wave (cm/s) 90 ± 20 80 ± 20 0.1 A wave (cm/s) 80 ± 20 60 ± 10 0.002 E/A ratio 1.3 ± 0.4 1.4 ± 0.4 0.2 E-DT (ms) 179.3 ± 37.8 170.4 ± 41.3 0.4 IVRT (ms) 75.7 ± 13.4 58.6 ± 6.1 0.01 MPI 0.62 ± 0.12 0.49 ± 0.05 0.0001 Tissue Doppler imaging
Med E0(cm/s) 8.7 ± 2.9 11.4 ± 4 0.002 Med A0(cm/s) 6.2 ± 2.5 5.3 ± 1.7 0.07 Med S0(cm/s) 7.5 ± 1.6 7.5 ± 2.1 0.9 Lat E0(cm/s) 9.0 ± 4.0 11.7 ± 3.4 0.01 Lat A0(cm/s) 7.0 ± 3.8 6.4 ± 1.8 0.3 Lat S0(cm/s) 8.3 ± 1.6 8.8 ± 2.2 0.4 Lat E/E0 11.1 ± 5 7.6 ± 2.2 0.002
TEE: Transthoracic Echocardiography; LVSWT: left ventricular septal wall thickness; LVEDD: left ventricular end diastolic dimension; LV PWT: left ventricular posterior wall thickness; LVESD: left ventricular end systolic dimension; EF: ejection frac-tion; Ao: aorta; LA: left atrium; MPI: myocardial performance index; E-DT: E wave deceleration time; Lat: lateral; Med: medial; IVRT: isovolumic relaxation time. Bold values mean significant p value.
coefficient = 2.4, 95% CI = 0.001–0.01; p = 0.021). The detailed multivariate linear regression analysis of the different factors affecting GLS, GCS and GSRivris shown inTable 4.
5. Discussion
The current study demonstrated significantly reduced CD133+/VEGFR2+and CD34+/VEGFR2+ EPC count in
SLE patients compared to controls. Experimental and clinical studies have demonstrated the important role of EPCs in tissue regeneration including neoangiogenesis, reendothelialization, repair of injured arteries and improvement of LV function fol-lowing myocardial infarction[6,17–21]. The current study find-ing of low EPCs in SLE patients is in agreement with the results of several other studies. Denny et al.[22]reported a sig-nificant decrease of CD34+/CD133+EPCs and myelomono-cytic circulating angiogenic cells (CACs) and a significant correlation of EPC count with SLEDAI score but not with the use of specific medications or daily corticosteroid doses. However, even those individuals with no clinical or serologic disease activity (SLEDAI = 0) had pronounced EPC decrease compared with controls. Lee et al.[23]demonstrated a mark-edly reduced level of EPC colony-forming units and the deple-tion of EPCs was more dramatic in SLE patients with elevated levels of IFN-I. The reduced EPC levels were not explained by use of common medications including steroids, anti-malarials, cytotoxic agents, or statins.
In our study, we could not find any significant correlation between EPC count and disease duration, SLEDAI score, pred-nisolone dose or duration of intake, HsCRP or ESR. The reduction of EPCs was even reported in SLE patients in an
inactive stage of disease, or in prolonged clinical remission [24,25]. Ebner et al. [8] reported an enhanced VEGFR2+/CD133+ EPC number whereas the number of VEGFR2+/CD34+cells and the proliferation rate were signif-icantly decreased. In the current study, the levels of immature VEGFR2+/CD133+ and mature VEGFR2+/CD34+ cells were reduced. The decrease in the number of circulating EPCs was also described in other diseases with vascular inflam-matory components, for example, rheumatoid arthritis and chronic renal failure [26,27]. The low levels of circulating EPCs in our study could be attributed to increased oxidative stress related to the inflammatory process associated with SLE and which was shown to inhibit EPC differentiation, survival, and function[28]. An alternative explanation is that continuous endothelial damage or dysfunction leads to an even-tual depletion or exhaustion of a presumed finite supply of EPCs involved in vascular homeostasis and endothelial repair. SLE has been shown to be an independent risk factor for endothelial dysfunction[3]. In a recent study of 38 lupus women without detectable myocardial ischemia on myocardial perfusion imag-ing, brachial artery flow mediated vasodilatation as a marker of endothelial function correlated strongly with E/E0as a marker
of LV diastolic function independent of systolic blood pressure, age, or lupus clinical damage index[29].
The second important finding of the current study is the echocardiographic abnormalities of both systolic and diastolic function in SLE patients with no clinically apparent CV dis-ease. Echocardiographic cardiac abnormalities were described more than 3 decades ago in SLE[30–32]. To the best of our knowledge, this the first study to investigate the correlation between LV deformation abnormalities as detected by STE
Figure 1 Automatically generated left ventricular (LV) deformation curves by the software (my lab60). (A) LV circumferential strain in the short axis view at the level of papillary muscles. (B) LV longitudinal strain in the four–chamber view. (C) LV longitudinal strain in the two–chamber view. (D) LV strain rate in the two–chamber view. The curves in white represent the average (global) strain or strain rates of different studied LV segments.
and EPC count in the peripheral circulation of SLE patients. As regards conventional TTE and TDI findings, SLE patients in the present study had a significantly higher LVESD com-pared to controls (p = 0.02). Although the LVEF of the
patients was in the normal range, it was significantly lower compared to controls (p = 0.007) suggesting subclinical sys-tolic dysfunction. The IVRT was significantly prolonged and the MPI was significantly higher in patients compared to
Table 3 Speckle tracking echocardiography (STE) data for the systemic lupus erythematosus patients and controls.
STE data Patients (n = 50) Control (n = 25) pvalue 4-Chamber view longitudinal strain (%)
Basal septal 14.3 ± 5.5 16.6 ± 2.6 0.01 Mid septal 16.2 ± 4.3 18.7 ± 2.3 0.002 Apical septal 18.3 ± 6.3 20.3 ± 3.7 0.2 Basal lateral 14.9 ± 3.7 19.8 ± 4.8 <0.001 Mid lateral 14.8 ± 3.8 19.1 ± 3.8 <0.001 Apical lateral 19.9 ± 26.7 18.2 ± 2.8 0.8
2-Chamber view longitudinal strain (%)
Basal inferior 11.1 ± 5.8 19.6 ± 4.3 <0.001 Mid inferior 13.5 ± 4.2 18.6 ± 2.9 <0.001 Apical inferior 14.9 ± 5.4 19.7 ± 4.1 <0.001 Basal anterior 13.2 ± 5.9 21.0 ± 5.2 <0.001 Mid anterior 13.1 ± 4.9 19.2 ± 5.0 <0.001 Apical anterior 12.7 ± 5.2 17.1 ± 4.1 <0.001 GLS (%) 14.5 ± 2.8 19.0 ± 1.3 <0.001
SAX view circumferential strain (%)
Mid anteroseptal 23.6 ± 11.0 30.3 ± 11.7 0.02 Mid anterior 20.5 ± 11.5 29.6 ± 11.5 0.002 Mid anterolateral 16.5 ± 7.4 24.6 ± 9.2 <0.001 Mid inferolateral 16.2 ± 6.0 22.7 ± 6.9 <0.001 Mid inferior 17.8 ± 6.5 24.3 ± 8.1 <0.001 Mid inferoseptal 21.0 ± 7.7 25.6 ± 9.1 0.04 GCS (%) 19.3 ± 6.8 26.2 ± 6.9 <0.001 GSR longitudinal systolic (1/s) 1.0 ± 0.2 1.1 ± 0.2 0.2 GSR longitudinal diastolic (1/s) GSRivr 0.14 ± 0.09 0.2 ± 0.1 0.01 GSRe 1.2 ± 0.3 1.3 ± 0.2 0.1 GSRa 0.8 ± 0.3 0.7 ± 0.2 0.2
STE: speckle tracking echocardiography; SAX: GLS: global longitudinal strain; GCS: global circumferential strain; GSR: global strain rate; ivr: isovolumic relaxation period; GSRe: global strain rate during early diastole; GSRa: global strain rate during atrial contraction; SAX: short axis. Bold values mean significant p value.
Table 4 Factors affecting global longitudinal strain (GLS), global circumferential strain (GCS) and global strain rate (GSR) during isovolumic relaxation period.
Variables GLS GCS GSRivr
ARC (95% CI) p ARC (95% CI) p ARC (95% CI) p Age 0.07 (0.06 to 0.19) 0.3 0.09 (0.2 to 0.4) 0.5 1.1 (0.002 to 0.01) 0.3 Disease duration 0.3 (1.18 to 0.19) 0.7 0.68 (2.6 to 4) 0.7 0.1 (0.05 to 0.05) 0.9 Steroid dose 0.007 (0.10 to 0.09) 0.9 0.24 (0.5 to 0.03) 0.03 0.1 (0.003 to 0.003) 0.9 Steroid duration 0.09 (1.52 to 1.34) 0.9 1.01 (4.4 to 2.2) 0.5 0.5 (0.04 to 0.06) 0.6 AZA/CYC 2.5 (0.49 to 5.48) 0.1 1.63 (5.2 to 8.4) 0.6 1.7 (0.02 to 0.19) 0.09 SLEDAI score 0.04 (0.2 to 0.12) 0.7 0.03 (0.3 to 0.4) 0.9 0.6 (0.01 to 0.004) 0.6 MPI 1.4 (5.64 to 7.51) 0.7 13.6 (2.5 to 29.7) 0.1 1.3 (0.001 to 0.01) 0.2 LVEF 0.08 (0.22 to 0.05) 0.2 0.08 (0.2 to 0.4) 0.6 2.4 (0.001 to 0.01) 0.02 EPCs VEGFR2+/CD133+ 0.002 (0.01 to 0.02) 0.8 0.01 (0.04 to 0.02) 0.5 0.7 (0.00001 to 0.001) 0.5 VEGFR2+/CD34+ 0.006 (0.06 to 0.05) 0.82 0.01 (0.12 to 0.14) 0.9 1.01 (0.003 to 0.001) 0.3 GLS: global longitudinal strain; GCS: global circumferential strain; GSRivr: global strain rate during isovolumic relaxation period; ARC: adjusted regression coefficient; CI: confidence interval; AZA/CYC: azathioprine/cyclophosphamide; SLEDAI: systemic lupus erythematosus disease activity index; MPI: myocardial performance index; LVEF: left ventricular ejection fraction; EPCs: endothelial progenitor cells. Bold values mean significant p value.
controls denoting diastolic dysfunction as well. In agreement with our results, a significantly lower LVEF was reported in SLE patients compared to controls (p < 0.001) in a study of 50 SLE patients. A significantly higher interventricular septum (IVS) and posterior wall (PW) dimensions, and Doppler mitral A/E ratio in patients compared to controls have been demon-strated[33]. In our study, there was no statistically significant difference in IVS, PW dimensions or trans-mitral flow Doppler E/A ratio between the patients and controls. A study compar-ing patients with SLE to those with antiphospholipid syndrome (APS), lupus patients had higher LVEDD and LVESD (p = 0.022 and 0.022, respectively), with a trend toward a lower fractional shortening (p = 0.07) compared to primary APS[10]. Cacciapuoti et al.[34]used TDI to calculate IVRT and MPI in 44 SLE patients without clinical signs of heart disease, and found as well significantly higher IVRT and MPI in patients compared to controls. The current study also demonstrated a significantly higher E/lateral E0 ratio in
patients compared to controls (p = 0.002) pointing again to diastolic dysfunction. Similarly, Lee et al. [35] reported a higher E/E0 in SLE patients compared to controls despite a
normal Doppler flow E/A ratio (p < 0.01) This study also described a lower E/E0ratio and higher LVEF in SLE patients
receiving angiotensin converting enzyme inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) compared to those not receiving these medications indicating their role in preserv-ing LV diastolic and systolic functions. None of our patients were receiving ACE-Is or ARBs because we excluded SLE hypertensive patients and the patients included were free of clinically manifest CV disease.
As regards STE findings, the current study revealed a signif-icantly lower LV GLS (p < 0.001), LV GCS (p < 0.001) and GSRivr (p = 0.01) in patients compared to controls. There
was no significant correlation between any of the studied vari-ables and GLS. By multiple logistic regression analysis, the independent variables affecting GCS and GSRivr were the
prednisolone dose and the LVEF respectively. (p = 0.028 and p = 0.021; respectively). These findings were in agreement with some aspects of the study by Buss et al. [36]who used TDI to calculate LV strain and strain rates in 67 young SLE patients. This study not only demonstrated significantly reduced GLS; a finding similar to our study but also detected significantly reduced GSSR, GSRe, GSRa in patients
com-pared to controls. Further, elevated SLEDAI score, resulted in significantly lower values for LV longitudinal function strain and strain rate. In the current study, we could not find any sta-tistically significant difference in GSSR, GSRe, GSRabetween
patients and controls. In a recent study using three-dimensional (3D) STE, although no difference in LV global systolic function was noted by standard echocardiography between patients and controls, 3D LVEF, LV GLS, LVGCS, LV global area stain (GAS) and global radial strain (GRS) were largely impaired in patients[37]. This study demonstrated also that GLS, GAS, GRS but not GCS were significantly decreased in those with severe disease activity than among those with no or mild activity (all p < 0.05). GLS was also independently correlated with SLEDAI score (p = 0.001). Yip et al.[12]showed that SLEDAI P1 was an independent predictor of LV longitudinal systolic dysfunction in SLE patients using TDI. In the present study, no correlation was detected between SLEDAI score and the different myocardial deformation parameters. The lack of a significant correlation
between SLEDAI score and evident LV diastolic dysfunction in SLE patients has been described before in previous studies [38,39]. In the present study, these LV subclinical abnormali-ties cannot be explained by increased prevalence of traditional CV risk factors such as smoking, HTN or DM because patients having them were excluded. The patients had however significantly higher cholesterol and triglyceride levels com-pared to controls. This may be the result of prednisolone which was prescribed to all patients. It is generally perceived that glucocorticoids have adverse effect on the lipid profile causing increase in both total cholesterol and triglycerides [40,41]. This high level of cholesterol and triglycerides may have induced subclinical coronary atherosclerosis in our patients. A high prevalence of myocardial perfusion abnormal-ities were detected in asymptomatic SLE patients without overt CV disease using single photon emission computed tomogra-phy [42,43]. In a study by Doria et al. [44], subclinical atherosclerosis has been shown to be more prevalent in SLE patients. Patients with carotid abnormalities were significantly older, had higher blood pressure and total serum cholesterol levels, and had taken a higher prednisone cumulative dosage than those without any lesions. By multivariate analysis, the cumulative prednisone dose remained associated with plaque formation after adjusting it for the classical Framingham atherosclerosis risk predictors. A significant association between carotid plaque formation in SLE patients and cumu-lative corticosteroid dosage as well as duration of treatment has been also reported by Manzi et al.[45]. In another study on Egyptian SLE patients, an increased prevalence of subclin-ical LV dysfunction was reported. SLE patients with positive tissue Doppler findings were of old age, had long disease dura-tion, high disease activity and nephritis [46]. In the current study, the prednisolone dose was the only independent variable adversely affecting LV GCS (p = 0.028). In a study of diabetic patients, those with coronary atherosclerosis as evidenced by increased calcium score in multi-slice computerized tomogra-phy scanner showed an impaired LV GLS, even though the LVEF was still preserved compared to those with no evidence of coronary atherosclerosis[47]. Hence, premature subclinical atherosclerosis may be the underlying cause of these subtle changes in LV function.
When we designed the current study, we hypothesized that EPCs might have a relation to any possible detected systolic or diastolic LV function abnormalities in SLE patients. These speculations were based on the findings of previous studies correlating EPC count to LV remodeling and function [9,21,48,49]. Peripheral blood CD34+cells and EPC mobiliza-tion occurs in heart failure (HF) and shows a biphasic response, with elevation and depression in the early and advanced phases, respectively[48]. In a study by Kissel et al. [9], the number of EPCs was found to be reduced, irrespective of the etiology of HF, whether ischemic or dilated cardiomy-opathy. On the other hand, in a study by Leone et al. [49], the concentration of CD34+bone marrow derived stem cells was not only higher in acute myocardial infarction (AMI) patients compared to patients with stable CAD but was also an independent predictor of global and regional improvement of LV function at the end of 1 year follow-up. In the TOPCARE-AMI trial, intracoronary infusion of circulating EPCs in patients with AMI resulted in an increased EF, reduced infarct size, and absence of reactive hypertrophy, sug-gesting functional regeneration of the infarcted ventricles at
the end of 1 year follow-up. In the current study, the inability to detect a statistically significant correlation between the EPC count and LV deformation abnormalities could be attributed to their detection in a quite early stage using STE or because of the small number of patients studied.
The first limitation is the cross sectional design of the study. The patients were not followed up to be able to examine the progression of LV systolic and diastolic abnormalities detected by STE or the effect of the low circulating EPCs on these abnormalities over time. The second limitation is the relatively small number of patients. This can be explained by the rigor-ous exclusion criteria. We actually excluded patients with clas-sical risk factors such as smoking, HTN or DM which were quite prevalent in lupus patients to avoid the impact of these factors on LV function.
In conclusion the relatively new STE can be used to diag-nose subtle abnormalities in LV function in SLE patients which could not be detected by conventional TTE or TDI. The low count of circulating EPCs detected in these patients was probably the result of the inflammatory process associated with SLE rather than early LV dysfunction which could only be detected by STE.
Conflict of interest None.
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