ASSESSMENT OF MYOCARDIAL VELOCITIES IN DIFFERENT DEGREES OF CORONARY ARTERY DISEASE BY TISSUE DOPPLER ECHOCARDIOGRAPHY

By

Mahmoud Alshahat Alsayed, Kamal Ahmed Marghany Mahgoub, Ahmed Abdel Hamid Rozza, Mansour Mohammed Mostafa,

Mohammed Adel Attia and Wael Mohammed Attia

Department of Cardiology, Faculty  of Medicine, Al-Azhar University, Egypt

ABSTRACT

Background: Tissue Doppler Imaging (TDI) is a rapid inexpensive and noninvasive method for the assessment of both the systolic and the diastolic cardiac function, and it has proved to be a useful prognostic tool both in the general populationand among persons with known cardiovascular diseases.

Objective: To determine how myocardial velocity assessed by pulsed TDI is affected by different degrees of CAD in patients with symptomatic CAD and preserved LV ejection fraction.

Patients and methods: A case-control study that included 40 patients with suspected CAD admitted at Bab El- Sha^,aria University Hospital, between July 2012 and January 2013, for coronary angiography. The  selected patients were divided into two groups: Group I (control group): Ten patients with normal coronary angiography or with insignificant lesions (less than 70%) in the coronary arteries by coronary angiography. Group II (Patient  group ) Thirty patients with significant stenosis (more than 70%) in the coronary arteries by coronary angiography. The second group was further subdivided into three subgroups: Group  A : patients with single vessel disease (SVD), Group  B : patients with two vessel disease (TVD), and Group  C : patients with multi vessel disease (MVD). For all patients, the data collected were full history taking and thorough clinical examination , twelve leads resting ECG, conventional echocardiography and pulsed tissue Doppler imaging and coronary angiography.

Results: There was  no statistically significant difference between the two groups as regard demographic characteristics including age, gender, cardiovascular risk factors including DM, hypertension, dyslipidemia, smoking and BMI. There was statistically significant difference between the two groups as regard Sm velocity, Ea velocity and E/Ea velocity ratio. There was no statistically  significant difference between the two groups as regard DT, E velocity, A velocity, E/A velocity ratio, Aa  velocity, Ea/Aa velocity ratio, IVCT, IVRT, ET and MPI .

      There was no statistically significant difference between the control and subgroups A, B, and C as regard demographic characteristics including age and gender but there was statistically significant difference between the three subgroups as regard BMI (Kg/m2) . There was no statistically significant difference between the three subgroups as regard diabetes mellitus, hypertension, and smoking and echocardiographic data including  Sm, Ea, Aa, E, A velocities, E/Ea and E/A velocity ratios,  DT, IVCT, IVRT, ET, MPI and EF.

      There was no statistically significant difference between the control group and  the subgroups A,B and C as regard demographic characteristics including age and gender, cardiovascular risk factors including DM, hypertension, smoking and  BMI and E-velocity, A- velocity, Aa velocity,  E/A ratio , Ea/Aa -velocity ratio, DT, IVRT, IVCT, ET and MPI. There was no significant difference between the control group and subgroup A, but  significant with subgroup B and very significant with subgroup C  as regard Sm velocity. There  was statistically no significant difference between the control group and  subgroup A, but very significant with subgroup  B and significant with  subgroup C  as regard  Ea-velocity. As regard E/Ea velocity, there was no statistically significant difference between the control group and subgroups  A and C but significant with subgroup B. 

Conclusion : Tissue Doppler  imaging  revealed  both systolic and diastolic dysfunction in patients with coronary artery disease even when ejection fraction  was preserved and the nature of the dysfunction depended on the severity of CAD.

Key word: CAD, Coronary angiography, Echocardiography, Tissue Doppler  imaging velocities.  

INTRODUCTION

    Despite a decline in mortality attributed to coronary artery disease (CAD), the burden of CAD remains high and is the leading cause of heart failure. This emphasizes the need for early detection of CAD in order to prevent heart failure and further reduce mortality due to CAD (Rosmond et al., 2008). Previous studies have demonstrated that TDI detects impaired diastolic and systolic function in ischemic myocardial regions. Hence, it has been proposed that TDI could be a useful diagnostic test in patients with suspected chronic CAD (Jarcia-Fernandez et al., 1999). Chronic CAD is a progressive disease with great variation in severity and if TDI is going to be a useful diagnostic test, it is necessary to clarify how the cardiac function is affected by different degrees of CAD (Bolognesi et al., 2009).TDI data display myocardial velocities throughout the cardiac cycle. The Doppler signals of the myocardium are of low intensity and high amplitude compared to that of red blood cells, which are of high velocity and low amplitude. Spectral pulsed wave Doppler (PW) provides better temporal and velocity resolution compared to the color method (Waggoner  and  Bierig , 2007). A number of parameters from TDI have been proposed to be useful in various cardiac diseases. In systole, potentially important prognosticators of TDI include peak systolic velocity in ejection period measured at mitral annulus (Sa) or at myocardial segments (Sm) as well as systolic dyssynchrony assessment. In diastole, potentially important progno-sticators include peak myocardial early diastolic velocity measured at the mitral annulus (Ea) or myocardial segments (Em) as well as measurement of transmitral to TDI early diastolic velocity ratio (E/Ea) (Ding et al., 2010). These myocardial velocity measurements with TDI have been shown to be useful in various diseases including heart failure (HF), hypertension, and acute myocardial infarction (MI), and in patients undergoing stress echocardiography for suspected coronary heart disease (Yu et al., 2003).Previous investigators have shown that the ratio of early diastolic mitral inflow (E) to early diastolic mitral annular tissue velocity (Ea) has a good correlation with left ventricular filling pressure (Sohin et al., 20013).We hypothesized that myocardial velocities assessed by TDI may be affected  by different degrees of CAD even with preserved LV systolic function. The study aimed to determine how myocardial velocity assessed by pulsed TDI is affected by different degrees of CAD in patients with symptomatic CAD and preserved LV ejection fraction.  

PATIENTS AND METHODS

      The present study included 40 patients with CAD, admitted at Bab El Sha^,aria University Hospital, between July 2012  and January 2013 for coronary angiography according to AHA/ACC guidelines for diagnosis of CAD.

Inclusion criteria: Sinus rhythm, patient with symptomatic CAD, age  > 20 years. Exclusion criteria: Patients with left ventricular ejection fraction (LVEF) < 50%, patients with prior myocardial infarction, patients with congestive heart failure, patients with valvular heart disease and  patients with intra ventricular conduction disturbances and arrhythmias. The selected patients were divided into two groups: Group I (control group); ten patients with normal coronary angiography or with insignificant lesions (less than 70%) in the coronary arteries by coronary angiography. Group II (patient group); thirty patients with significant stenosis (more than 70%) in the coronary arteries by coronary angiography. The subjects of group II were further subdivided into three subgroups:Group A; patients with single vessel disease (SVD), Group  B; patients with two vessel disease (TVD), and Group  C; patients with multi vessel disease (MVD). All patients were subjected for the following:

1. Informed consent about the type of the study.

2. Full history taking and thorough clinical examination, and risk factors of CAD were established.

3. Twelve leads resting ECG.

4. Conventional echocardiography and pulsed tissue Doppler imaging: All patients were examined with conven-tional two-dimensional echocardio-graphy and pulsed TDI by Philips Sonos. Pulsed wave Doppler at the apical position was used to record mitral inflow between the tips of the mitral leaflets. Peak velocity of early (E) and atrial (A) diastolic filling and deceleration time of the E-wave (DT) were measured, and the E/A-ratio was calculated. LVEF was determined by conventional two-dimensional echocardiography (Manouras et al., 2009). Pulsed TDI loops were obtained in the apical four, two-chamber and apical long-axis view at the highest possible frame rate. Measurements were made for peak systolic (Sa), peak early diastolic (Ea), and late peak diastolic myocardial velocities (Aa), and the Ea/Aa ratio at  the six mitral annular sites dividing the left ventricle into six segments of interest; the septal, lateral, inferior, anterior, posterior, and anteroseptal myocardial walls.Global longitudinal performance of the left ventricle was assessed by averaging the velocities from the six segments of patients and control group and comparing the velocities from the six segment of patient with the control group  (Olsen et al., 2009). For every patient, we measured (IVRT, IVCT& ET) and from it we calculated myocardial performance index (TIE index).

5. Coronary angiography: Selective coronary angiography by standard Judkin, s technique was performed for all subjects with the femoral approach and patients who found to have significant coronary stenosis were subdivided into three groups according to the vessels affected: Group A; patients with significant one-vessel disease, patients with significant left anterior descending artery (LAD) stenosis or right coronary artery (RCA) stenosis or left circumflex artery stenosis (LCX). Group B; patients with significant two-vessel disease, patients with significant LAD and circumflex artery (Cx) stenosis or significant left main artery stenosis or significant LAD and RCA stenosis, and group C; patients with significant three-vessel disease (Soren et al., 2010).

Statistical analysis: Data were coded and entered using the statistical  registered version of the  Graph Pad  InStat Version  3.00 Created  For  win 98. Two types of statistics were done:

1. Descriptive statistics: mean(x)±standard deviation (SD) for  quantitative (Continuous) variables and number and percentage for qualitative (categorical) variables.

2. Analytic statistics: Paired t-test, unpaired t-test. P value < 0.05 was considered    statistically significant.

RESULTS

Demographic characteristics and risk factors for CAD in the control and  patient groups (Table 1).

Group I: Mean age ± SD was (50.2 ± 6.89) years. Gender : Four patients (40%) were males and six patients (60%)  were females. Mean BMI ± SD was 20.8 ± 1.476 kg⁄m². Risk Factors: Two patients (20%) were diabetic and eight patients (80%) were non diabetic.  One patient (10%) was hypertensive and nine  patients (90 %) were non hypertensive. Three patients ware dyslipidemic and seven patient ware non dyslipidemic. Three  patients (30 %) were smokers and seven  patients (70 %) were non smokers. Group II: Mean age ± SD was 45.7±7.475 years. Gender : Nineteen patients (63.33%) were males and eleven patients (36.67%) were females. Mean BMI ± SD was  20.6671.295 kg⁄m². Risk Factors: Twelve  patients (40 %) were diabetic and eighteen patients (60%) were non diabetic. Eighteen patients (60%) were hypertensive and twelve  patients (40%) were non hypertensive. Thirteen patients were dyslipidemic and seventeen  patients ware non dyslipidemic. Fifteen patient (50%) were smokers and fifteen patients (50%) were non smokers. There was no statistically significant difference between the two groups as regarddemographic characteristics including age, gender, cardiovascular risk factorsincluding DM, hypertension, dyslipidemia, smoking and BMI.

Table (1): Comparison between the two main groups according to patient´s demographic characteristics and risk factors.

     There was a statistically significant difference between the two groups as regard Sm velocity, Ea velocity and E/Ea velocity ratio. There was no statistically  significant difference between the two groups as regard DT, E velocity, A velocity, E/A velocity ratio, Aa  velocity, Ea/Aa velocity ratio, IVCT, IVRT, ET, MPI  (Table 2).

Table (2): Comparison between the two  main groups according to echocardiographic data (Mean ± SD).

Demographic characteristics and risk factors for CAD (Table 3)

Subgroup A: Mean age ± SD was 53.178± 7.655 years. Sex: Four patients (10 %) were males and seven patients (17.5%)  were females. Mean BMI ± SD was 20.455±.0688 kg⁄m². Risk Factors: Two patients (5 %) were diabetics and nine patients (22.5 %) were non diabetics. Six patients (15 %) were hypertensive and five patients (12.5 %) were non hypertensive. Four patients (10%) were smokers and seven patients (17.5%) were non smokers.

Subgroup B: Mean age ± SD was 45.615±9.188 years. Sex: Seven patients (17.5%) were males and six patients (15%)  were females. Mean BMI ± SD was 20.308±1.182 kg⁄m². Risk Factors: Seven patients (17.5 %) were diabetics and six patients (15 %) were non diabetics. Seven patients (17.5%) were hypertensive and six patients (15 %) were non hypertensive.  Seven  patients (17.5%) were smokers and six patients (15%) were non smokers.

Subgroup C: Mean age ± SD was 52.866 ±6.927 years. Sex: One male patient (2.5%) and five  patients (12.5 %)  were  females. Mean BMI ± SD was 21.833±1.835 kg⁄m². Risk Factors: Three  patients (7.5%) were diabetics and three patients (7.5%) were non diabetics. Five patients (17.5%) were hypertensive and one non hypertensive patient (10.29 %). Four patient (10%) were smokers and two patients (5%) were non smokers .

Table (3):Comparison between the three subgroups according to patient´s demographic characteristics and risk factors.

      There was no statistically significant difference between the three subgroups as regard demographic characteristics including age and gender, diabetes mellitus, hypertension, and smoking . There was statistically significant difference between the three subgroups as regard BMI (Kg/m2). There was no statistically quite significant difference between the three subgroups as regard echocardiographic data including  Sm, Ea, Aa, E, A velocities, E/Ea and E/A velocity ratios,  DT, IVCT, IVRT, ET, MPI and EF  (Table 4).

Table (4): Comparison between the three subgroups according to echocardiographic data (Mean±SD).

     There was  no  statistically significant difference between Group I and  the three subgroups of group II as regard demographic characteristics including age, gender, cardiovascular risk factors including DM, hypertension, smoking and  BMI (Table 5) .

Table (5): Group I (control group) and  the three subgroups (A,B,C) of group II according to patient´s demographic characteristics and risk factors (Mean ± SD).

      There was no significant  difference between Group I and  subgroup  A,  but significant with subgroup B and  subgroup C  as regard Sm velocity. There  was statistically no significant difference between Group I and  subgroup A, but significant with subgroup  B and subgroup C  as regard  Ea-velocity. As regard E/Ea velocity, there was no statistically  significant difference between group 1 and subgroups A and C, but significant with subgroup B. There was  no   statistically significant difference between Group I and  the three  subgroups as regard  E-velocity, A- velocity, Aa velocity,  E/A ratio , Ea/Aa -velocity ratio, DT, IVRT, IVCT, ET and MPI  ( Table 6).

Table (6): Group I (control group) and the three subgroups (A,B&C) according to patient´s echocardiographic data (Mean ± SD)

DISCUSSION

      Tissue Doppler imaging (TDI) is used clinically to evaluate quantitatively myocardial motion velocity, and several studies have reported the clinical importance of TDI by comparing systolic and diastolic parameters determined by conventional methods with values obtained with TDI (Garcia et al.,1998). Previous studies have demonstrated that TDI detects impaired diastolic and systolic function in ischemic myocardial regions. Hence, it has been proposed that TDI could be a useful diagnostic test in patients with suspected chronic CAD (Jarcia-Fernandez et al., 1999). Chronic CAD is a progressive disease with great variation in severity and if TDI is going to be a useful diagnostic test, it is necessary to clarify how the cardiac function is affected by different degrees of CAD (Bolognesi  et al., 2009). The aim of this study was to determine that  the myocardial velocities assessed by pulsed TDI is affected by different degrees of CAD in patients with symptomatic CAD and preserved LV ejection fraction. There was statistically significant difference between the CAD patients (Group 2) and the control group (group 1 ) as regard Sm, Ea and  E/Ea. When we compared the control group with the three patient subgroups, we found that, as regard  Ea velocity, there was no significant difference between the control group and group ( A), but significant with group (B)  and group (C). As regard E/Ea velocity, there was no statistically  significant difference between control group ( group 1) and group ( A and  C) but significant with group (B). As regard Sm velocity,  there was no statistically  significant difference between control group (group 1) and group (A) but significant with group (B) and group (C). However, there were no statistically significant diffe-rences between the three subgroups as regard Sa, Ea and E/Ea . Hence, the findings of this study supported the previous reports which suggested that tissue Doppler velocities (Ea and  Sa) decrease with increase number of coronary arteries with significant stenosis. The finding of the study done by Soren et al.(2010)  was similar to our study except that late diastolic tissue Doppler velocity (Aa) velocity: Our study demonstrated that there was  no significant changes between patient and control groups and between the three subgroups. This  result was supported  by the study done by Divid et al. (2009) which demonstrates that ischemia may affect mainly the diastolic active process without affecting the passive phase (atrial contraction). There-fore, during ischemia, there is a decrease in early diastolic velocity (E wave) without any change in late velocity (A wave) resulting in an inverted E/A ratio. The alteration of LV global diastolic filling depends on the magnitude and extension of regional diastolic dysfunction caused by myocardial ischemia. The study by Jarcia-Fernandez et al. (1999) is similar to our study except that IVRT was not significantly affected as we measured it globally not regionally. In the study by Bolognesi et al. (2009), the  extent of the percentage of left ventricular longitudinal shortening and the systolic peak velocity at echo-tissue Doppler were significantly higher in the control patients than in patients with CAD. Left ventricular end-diastolic pressure was higher in patient with CAD. Hence, the findings of this study support the result of our study that tissue Doppler velocities (Ea & Sa) decreased in patients with CAD. As regard  myocardial performance index (TIE Index), our study demonstrates no significant difference between patient and control group as regard TIE Index. In the study by Sohin et al.( 2013) concluded that although the normal EF, MPI value impaired in proportion to the severity of CAD in patients with stable CAD. Findings of this study was not the same of our study which may be due to low number of our study. In the present study, there was no statistically  significant difference between the two groups as regard BMI, sex, smoking, prevalence of DM, and there was statistically  significant difference between the two groups as regard  HTN. This was probably due to personal variation.

     This study has some limitations which should be addressed in further studies. Regional wall motion abnormalities may be due to other condition other than ischemia such as age, diabetes, intra ventricular conduction delay and fibrosis. The presence of coronary artery lesion assessed by CA is not necessary associated with ischemia sample. On the other hand, ischemia may present in the control  without significant stenosis due to microvascular ischemia, and the region of ischemia supplied by stenotic arteries may be supplied by collateral arteries.

CONCLUSION

     Tissue Doppler  imaging  revealed both systolic and  diastolic dysfunction in patients with coronary artery disease even when ejection fraction  was preserved and the nature of the dysfunction depend on the severity of CAD.

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