European Journal of Cardiovascular Medicine

The diagnosis and assessment of chronic coronary syndrome (CCS) involves clinical examination, identifying risk factors for atherosclerosis, and specialized cardiac investigations such as different stress testing modalities and coronary imaging [1].

Noninvasive CAD patient identification is still a clinical issue, despite the extensive use of imaging and provocative testing; on coronary angiography, over half of the patients exhibited normal or non-obstructive CAD [2].

The identification of aberrant wall motion in the left ventricle (LV) and the measurement of the LV ejection fraction (EF) are the primary factors in the echocardiography diagnosis of CAD. But there aren't any unusual LV wall vibrations at rest in CAD patients without a history of myocardial infarction [3].

The strain values are better than either wall motion or tissue Doppler in the assessment of regional contraction.

Also, strain can be employed in determining myocardial viability either at rest or with stress [4].

2D-STE is more accurate than traditional 2D echocardiography in assessing regional and global myocardial function as well as infarct size, viability of the infarcted myocardium, and mild changes of myocardial ischemia because significant coronary artery stenosis may result in persistently impaired longitudinal LV function at rest [5].

Due to its semi-automated nature, speckle tracking echocardiography offers good repeatability both within and between observers [6].

One of the main objectives of clinical cardiology is the non-invasive measurement of regional myocardial function. Based on the concepts of "strain" and "strain rate" imaging, an ultrasonic technique that measures regional deformation has been developed; it needs one cardiac cycle for additional offline processing and interpretation [7].

Longitudinal strain offers a good quantitative myocardial deformation assessment of each LV segment, enabling early detection of systolic dysfunction in patients with preserved LV ejection fraction [8]. Additionally, a strong correlation between longitudinal strain and the left ventricular ejection fraction (LVEF) has been demonstrated [9].

The use of STE longitudinal strain can identify and risk stratify CAD with good accuracy and repeatability.

Strain and SR are homogeneously distributed across the myocardium, therefore small increases in either metric suggest myocardial dysfunction. Strain imaging can be used to diagnose and treat almost any cardiac condition, but it is most useful in identifying ischemic heart disease [10].

The Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score aims to describe coronary anatomy based on anatomic criteria, such as lesion site and complexity; it can predict clinical outcomes after PCI or CABG in multiple vessel disease (MVD) patients and/or left main coronary artery disease [11].

This study is cross-sectional and prospective. It was carried out on seventy patients who came to the cardiology outpatient clinic complaining of chest pain in order to be evaluated for myocardial ischemia.

Enrollment of patients begun in December 2022 and was completed in December 2023.

Symptomatic individuals suspected to have stable coronary artery disease aging 20–80 were included in the study.

Exclusion conditions

Individuals with high-risk unstable angina or sudden myocardial infarction.Patients have a history of past myocardial infarction or previous recent coronary revascularization.Individuals with anomalies in regional wall motion during resting echocardiogram. Patients having structural cardiac disease, e.g., significant left ventricular hypertrophy. Patients with more than mild valvular lesions.

Patients having suboptimal echogenic window. Individuals who frequently experience additional systoles or persistent arrhythmias

Every participant in the research has undergone the following:

Careful history collection and comprehensive physical examination.

12-lead surface ECG

Two-dimensional speckle tracking echocardiography: Three standard apical images were obtained at rest according to the American Society of Echocardiography guidance. Gain, depth, and sector width were changed properly in order to set the frame rate 60 to 80 frames/s. Using the Cardiac Motion Quantification (CMQ) capability on the Q lab 9 software (Philips ultrasonography), a well-defined cardiac cycle was obtained for each view and digitally recorded for offline analysis.

The aortic valve closure (AVC) as observed in the apical long-axis view was used to first define the end-systole. Then, the region of interest (ROI) was set by identifying three locations at the end-diastolic frame; 2 annular points low and inside the myocardium at the level of insertion of the mitral valve and 1 apical point at the endocardial border of the apex. In the ensuing frames in 30 seconds, the software automatically tracks the external (epicardial) and interior (endocardial) borders.

In addition to a shared apical cap, the software divides each ROI equally into three segments: basal, mid, and apical. The operator approved or refused the tracking and made any necessary manual corrections.

For every segment from every angle, the longitudinal strain was automatically displayed both numerically and graphically. Using the same sequence, the apical 4- and apical 2-chamber views underwent the same process. Finally, after completion of the analysis of the three apical views, the software provides a 17 segment bull’s eye display of the peak longitudinal systolic strain with automatic computation of the mean global longitudinal strain (GLS)

Coronary angiography: All patients underwent coronary angiography on a Siemens Axiom Artis coronary angiographic system (Siemens, Erlangen, Germany) within 1 month of the echocardiogram.

Selective left and right coronary angiography in multiple views in order to avoid side branch overlaps and foreshortening of the significant coronary stenosis.

SYNTAX I score calculation: An expert operator who was blind to the STE results assessed every image. The SYNTAX score was calculated from the accumulation of the individual scores for each independent lesion defined as ≥ 50% luminal blockage in vessels ≥ 1.5 mm. The SYNT AX scores were calculated for all patients using dedicated software (available at http://www. syntaxscore.com/calc/start.htm). Thereafter, the patients were split into 3 groups based on the presence and/or the severity of coronary artery disease (CAD): no CAD on angiography (n = 10, control group), low SS (n = 25, SS < 22), and high SS (n = 35, SS ≥ 22)

Analysis of statistics

SPSS software statistics computer package version 18 (SPSS Inc., USA) was used to arrange, tabulate, and statistically analyze the gathered data. The mean and standard deviation (SD) were calculated for quantitative data. One-way ANOVA or the independent t test were employed to compare any two or three groups, respectively. Chi-square (χ2) was employed as a test of significance, and qualitative data were displayed as numbers and percentages. The relationship between the SYNTAX score and GLS and research parameters was determined using Pearson's correlation.

The discrimination value of GLS for low and high SYNTAX scores as well as the ideal cut-points for sensitivity and specificity were established using the receive operating characteristic (ROC) curve. Significance was set at p ≤ 0.05 for the interpretation of test results.

Ethics clearance and participation consent

Our institutional ethics committee approved the study, and each patient provided informed written consent in accordance with the guidelines set forth by our faculty's local ethical committee (committee reference number: not applicable).

There were no significant statistical differences between CAD and control groups as regard age, sex, DM, HTN, dyslipidemia, smoking, LVEDD, LVESD, and EF (p > 0.05) AP4 longitudinal strain (14.9±4.5 vs. 18.7±1.9, p<0.001), AP3 longitudinal strain (13.3±2.4 vs. 17.2±1.8, p<0.001), AP2 longitudinal strain (13.1±3 vs. 16.7±2.3, p<0.01), and global longitudinal strain (15.1±2.3 vs. 19.5±1.3, p<0.001).

LVEDD and LVESD (p<0.001), E/Aratio (p<0.04), AP2L strain, AP3L strain, AP4L strain, and GLS (p<0.001) were all strongly linked with higher SYNTAX scores

In order to identify high and low syntax scores, peak GLS cutoff values of 18.8 and 17.5 demonstrated 74% and 83% sensitivity 67 % and 94% specificity, respectively.

Echocardiography is an important cardiac imaging tool in individuals with suspected heart illness. However, the majority of individuals with no prior myocardial infarction or myocardial stunning have no motion abnormalities at rest, hence traditional echocardiography has minimal usefulness in the diagnosis and risk classification of suspected CAD patients.Therefore, it would be very helpful to develop another resting module to diagnose and predict the severity of CAD [12].

The three components of myocardial deformation can be quickly, quantitatively, and angle-independently assessed using speckle tracking echocardiography (STE), a semi-automated program that is highly feasible and reproducible, especially for the longitudinal one.The viability of STE-derived longitudinal strain analysis as an additional technique for CAD identification was validated by a number of clinical trials [13].

In this prospective study, 70 individuals between the ages of 20 and 80 were gathered from an outpatient cardiology clinic; each patient underwent coronary angiography and echocardiography (including conventional and STE), and the results were gathered and analyzed.

We could identify a cut-off value of GLS with high sensitivity and specificity to detect a high SYNTAX score.

When compared to individuals with non-obstructive CAD, Biering-Sørensen et al. [14], Gaibazzi et al. [15], and Billehaug et al. [16] demonstrated that GLS is significantly lower in patients with obstructive CAD (at least one stenosis>50% or≥70% luminal area reduction), and our investigation produced similar findings.

GLS measures show a moderate diagnostic accuracy in predicting substantial CAD in patients who arrive with chest discomfort, according to Billehaug et al. [16]. They demonstrated that the GLS cutoff value for CAD prediction ranged from -17.4 to -19.7%, with sensitivity ranging from 51 to 81% and specificity from 58 to 81%. This result could be explained by the impact of afterload and diastolic function on GLS.

According to our research, GLS gradually declined as the SYNTAX score increased, indicating a worsening of CAD. Vrettos et al. [17] showed similar results when they evaluated 71 individuals and re ported that GLS values were inversely connected to SYNTAX score values. And they demonstrated that the GLS optimal cutoff value to detect patients with high SYNT AX score was − 13.95 (sensitivity = 71%, specificity = 90%, p < 0.001).

There was a positive correlation between high SYNT AX score and being diabetic (p = 0.007); this was also noted in Srinivasan et al. [18] where they observed that patients with 5–10years of diabetes mellitus have a significant increase in the mean SYNTAX score (p = 0.019) when compared to those with less diabetes duration.

There was also a positive link (p = 0.001) between smoking and the SYNTAX score. A statistically significant connection (p < 0.05) between the SYNTAX score and age, hypertension, diabetes mellitus, dyslipidemia, and smoking was found in a number of investigations, including El Kersh et al. [19].

El-Sayed et al. [20] found that high SYNTAX score patients have higher E/A ratio and lower deceleration time (DT) when compared with the low SYNTAX score patients (p = 0.016 and p = 0.046, respectively) while our study did not reach these results as the E/A ratio was lower in the high SYNTAX group (p = 0.04).

Similar to the findings of Elgohary et al. [21], who compared the results of patients with controlled and uncontrolled diabetes and discovered a significant statistical difference in GLS, age, diabetic duration, 2HPP blood sugar level, and E/é ratio in patients with controlled DM compared to uncontrolled DM, our study found that the mean GLS was lower in diabetic patients (13.7 ± 2.4) than in non-diabetics (15.8 ± 2.7 (p = 0.001). Another study by Wierzbowska-Drabik et al. [22] indicated that during DSE global and regional LV peak, systolic longitudinal strain revealed lower values in DM patients when compared to non-diabetics: 14.5 ± 3.6% vs. 17.4 ± 4.0% at rest; p = 0.0001.

However, when Farsalinos et al. [23] examined cardiac function in young, healthy heavy smokers, they observed no significant changes in GLS, despite our finding that smokers had considerably reduced mean GLS (p = 0.002).

Our study results indicated a good association between left ventricular EF and GLS (r = 0.25; p = 0.04), and Benyounes et al. [24] reported similar results when they approved that two-dimensional GLS can predict LVEF (r = − 0.53; p < 0.001). Additionally, Lima et al. [25] found a strong correlation between left ventricular EF and GLS (r = 0.95; r2 = 0.89; p < 0.001), particularly in patients with LV systolic dysfunction compared to those with normal LVEF.

Normal left ventricular wall motion at rest cannot exclude severe CAD. GLS and CAD complexity, as measured by the popular SYNTAX score, are significantly correlated. With a high sensitivity for the identification of low and high SYNTAX scores, respectively, resting 2D-STE-derived global longitudinal strain (GLS) can predict severe CAD.Severe CAD cannot be ruled out by normal left ventricular wall motion at rest.

There is a strong correlation between GLS and CAD complexity as determined by the widely used SYNTAX score.

Limitations

Excluding patients with wall motion abnormalities at baseline echocardiography.

In addition to myocardial ischemia, other factors that affect strain and strain rate include left ventricular mass, different hemodynamic variables, and software platform type. Each of these elements may be a confounding factor.

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