Predictive Value of Global Longitudinal Strain Imaging in Detecting Significant Coronary Artery Disease in Patients with Non-ST-segment Elevation Myocardial Infarction

Ravi Vishnu Prasad; Gutte Rahul Manikrao; BP Singh; Nirav Kumar; Goutam Kumar; Chandra Bhanu Chandan

doi:10.4103/jiae.jiae_2_23

ORIGINAL RESEARCH

Year : 2023 | Volume : 7 | Issue : 2 | Page : 80-84

Predictive Value of Global Longitudinal Strain Imaging in Detecting Significant Coronary Artery Disease in Patients with Non-ST-segment Elevation Myocardial Infarction

Ravi Vishnu Prasad, Gutte Rahul Manikrao, BP Singh, Nirav Kumar, Goutam Kumar, Chandra Bhanu Chandan
Department of Cardiology, India Gandhi Institute of Medical Sciences, Patna, Bihar, India

Date of Submission	08-Jan-2023
Date of Decision	23-Apr-2023
Date of Acceptance	27-Apr-2023
Date of Web Publication	15-Jun-2023

Correspondence Address:
Dr. Ravi Vishnu Prasad
Department of Cardiology, India Gandhi Institute of Medical Sciences, Sheikhupura, Patna - 140 008, Bihar
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiae.jiae_2_23

Abstract

Background: Two-dimensional speckle-tracking echocardiography (2D-STE) is a newer method for assessing left ventricular (LV) systolic function. The aim of this study was to assess the predictive value of 2D global longitudinal strain (GLS) in the detection of longitudinal LV systolic dysfunction and the identification of significant coronary artery disease (CAD) in non-ST-segment elevation myocardial infarction (NSTEMI) patients without wall motion abnormalities. Materials and Methods: We enrolled 100 patients who were suspected cases of NSTEMI with echocardiography showing LV ejection fraction >50% and no regional wall motion abnormality. LV myocardial function was assessed using conventional echocardiographic measurements and myocardial deformation analysis with 2D-STE. The patients found to have significant CAD on coronary angiography were included in the cases group and those without significant CAD were considered as controls. Results: Mean age of the patients was 58.36 ± 11.21 years versus 56.54 ± 8.10 years in controls. Male preponderance was found in both case and control groups, with 66% (n = 33) and 56% (n = 28) males, respectively. The patients had significantly lower GLS as compared to the controls (-16.31 ± 1.34% vs -19.17 ± 1.63%, P < 0.001). The patients with positive troponin assay had a lower mean GLS −16.49 ± 1.5% as compared to those with negative troponin assay (−19.32 ± 1.54%, P < 0.001). Multivariate analyses indicated that GLS was an independent predictor of CAD in those with NSTEMI (GLS odds ratio = 0.024, P < 0.001). Conclusions: The present study demonstrates that 2D-STE is superior to conventional echocardiography in excluding significant CAD. It is a promising, easy to perform, bedside tool for diagnosis and prognostication in patients with NSTEMI. GLS has a potential to be used in conjugation with other risk stratification strategies to identify patients at high risk.

Keywords: Coronary artery disease, global longitudinal strain, non-ST-segment elevation myocardial infarction

How to cite this article:
Prasad RV, Manikrao GR, Singh B P, Kumar N, Kumar G, Chandan CB. Predictive Value of Global Longitudinal Strain Imaging in Detecting Significant Coronary Artery Disease in Patients with Non-ST-segment Elevation Myocardial Infarction. J Indian Acad Echocardiogr Cardiovasc Imaging 2023;7:80-4

How to cite this URL:
Prasad RV, Manikrao GR, Singh B P, Kumar N, Kumar G, Chandan CB. Predictive Value of Global Longitudinal Strain Imaging in Detecting Significant Coronary Artery Disease in Patients with Non-ST-segment Elevation Myocardial Infarction. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2023 [cited 2023 Oct 4];7:80-4. Available from: https://jiaecho.org/text.asp?2023/7/2/80/378795

Introduction

Acute coronary syndrome (ACS) is a leading cause of morbidity and mortality in the world. The incidence of ACS is increasing in developing countries including India.^[1] The proportion of ST-segment elevation myocardial infarction (STEMI) patients in ACS varies in different observational studies but has declined over the past decade due to the introduction of more sensitive assay of myocardial injury that has increased the number of non-STEMI (NSTEMI).^[2] Among patients admitted to emergency services with acute onset chest pain, 15%–20% have diagnosis of NSTEMI.^[3]

Noninvasive identiﬁcation of patients with coronary artery disease (CAD) remains a clinical challenge despite the widespread use of imaging and other diagnostic measures. More than 50% of patients, referred for coronary angiography, show normal coronary arteries.^[4] Severe CAD may lead to left ventricular (LV) dysfunction; however, the LV ejection fraction (LVEF) is usually found normal at an early stage.^[5] Thus, establishing a more sensitive index for early-stage LV dysfunction is of great importance. Two-dimensional speckle-tracking echocardiography (2D-STE) has emerged as a useful modality in this context.^[6] Global longitudinal strain (GLS) and strain rate analyses using 2D-STE have been shown to be superior to conventional echocardiographic imaging for LV function assessment.^[7] In patients with NSTEMI, the conventional echocardiographic assessment reveals normal findings in 25%–76% of patients, whereas GLS could detect impaired ventricular function in many of these patients.^[8]

Materials and Methods

One hundred patients with suspected NSTEMI with echocardiography showing LVEF >50% and no regional wall motion abnormality were enrolled. LV myocardial function was assessed using conventional echocardiographic measurements and myocardial deformation analysis with 2D-STE.

Inclusion criteria

Patients having signed an informed consent form
Patients aged between 18 and 80 years of age
Suspected diagnosis of NSTEMI as per universal definition of acute myocardial infraction.

Exclusion criteria

Patient unwilling or unable to sign consent
Patients younger than 18 years and older than 80 years of age
Known cardiovascular disease
Severe kidney disease (estimated glomerular filtration rate below 30 mL/min/1.73 m²)
Malignancy
Sepsis
Complete bundle branch block in surface electrocardiogram (ECG)
Moderate-to-severe valvular heart disease
Atrial fibrillation with heart rate faster than 100 beats/min
Insufficient echocardiographic echogenicity, wall motion abnormality, and LVEF below 50%.

The Ethics Committee of the Indira Gandhi Institute of Medical Sciences, Patna, had given clearance for doing the study. Informed consent was obtained from the participants. The study population was evaluated with detailed clinical history, physical examination, and routine laboratory parameters along with serum troponin level estimation. ECG was recorded within 10 min of the patient presentation to the emergency department. Conventional echocardiography and longitudinal strain imaging were performed after admission. Echocardiographic images were obtained in the parasternal long-axis and short-axis, apical two-chamber, three-chamber, and four-chamber views with standard transducer positions. Conventional echocardiographic measurements were done according to the American Society of Echocardiography guidelines.^[9] LV end-diastolic and end-systolic diameters, interventricular septal, and posterior wall thicknesses were recorded in the parasternal long-axis view. LV end-systolic volume and end-diastolic volume were measured in the apical four-chamber and two-chamber views. LVEF was calculated using the modified Simpson's biplane method. Myocardial deformation analysis was performed using 2D-STE. Analyses were made with QLAB-CMQ software (Philips Medical Systems, Andover, MA). The end-diastole was defined as the peak of the R-wave in the ECG, and the end-systole was defined as the closure of the aortic valve. Endocardial border was identified in the 2D images at the end-systole and a region of interest was automatically generated. In case a correction was needed due to false auto-tracking, the endocardial border tracing and the width of the region of interest were adjusted to ensure a complete endo-epi tracking along the entire LV wall segments before computation of strain data. All three apical views (apical four-chamber, apical two-chamber, and apical three-chamber views) were analyzed. Peak systolic longitudinal strain values were recorded automatically for each of the 18 LV myocardial segments and the mean value was used as the GLS.

Coronary angiography was performed on each patient during the index hospitalization according to the current treatment guidelines. Significant CAD was defined as at least one epicardial coronary artery having more than 50% stenosis. Patients with <50% narrowing were included in the control group. The patients were treated with pharmacological, nonpharmacological, and invasive strategy as per the European Society of Cardiology guidelines and the risk stratification.^[10]

Statistical analysis

Statistical analysis was carried out with the help of Statistical Package for the Social Sciences (SPSS) Statistics for Windows (version 24.0, Professional) (IBM Corp., Armonk, N.Y., USA). Univariate and multivariate logistic regression analyses were used to identify independent variables of CAD. For the echocardiographic parameters, receiver operating characteristic (ROC) curves were obtained for GLS and the cut-off value providing optimal sensitivity and specificity was identified for the prediction of CAD.

Results

The present study was conducted at the Indira Gandhi Institute of Medical Sciences, Patna, from July 2020 to December 2021. [Table 1] demonstrates the clinical and demographic characteristics of 50 patients with significant coronary artery stenosis and 50 patients without significant coronary artery stenosis.

Table 1: Clinical and demographic characteristics of the patients with and without significant coronary artery disease

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Mean age of the patients was 58.36 ± 11.21 years versus 56.54 ± 8.10 years in controls. Male preponderance was found in both case and control groups, with 66% (n = 33) and 56% (n = 28) males, respectively. The incidence of diabetes mellitus, hypertension, and dyslipidemia were comparable between the two groups. There was no statistically significant difference between the two groups when hemoglobin and serum creatinine levels were compared. All patients among cases had troponin positive, while only one patient had frank positive and five had faint positive results of troponin in the control group.

As per the study design, all subjects in the control group had normal or noncritical coronary angiography findings. Among the cases, single vessel disease (SVD) was the most common (52%, n = 26), followed by triple vessel disease (TVD, n = 14, 28%) and double vessel disease (DVD, n = 10, 20%). Among those having SVD, the left anterior descending artery was the most involved coronary artery (n = 13, 50%), followed by left circumflex artery (n = 8, 30.8%) and the right coronary artery (n = 5, 19.2%).

The mean GLS value in the case group was -16.31 ± 1.34% and in the control group -19.17 ± 1.63% (P < 0.001). The patients with positive troponin assay had a lower mean GLS -16.4 ± 1.5% as compared to those with negative troponin assay (-19.32 ± 1.54%, P <0.001, [Table 2]]. The GLS values did not differ according to the type of coronary artery involvement (P = 0.132). However, there was a statistically significant reduction in GLS with increasing number of vessel involvement (P <0.001, [Table 3]). The GLS values in patients with SVD, DVD and TVD were -16.6 ± 0.74%, -16.26 ± 0.53%, and − 14.71 ± 0.55%, respectively.

Table 2: Association of troponin levels with global longitudinal strain

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Table 3: Association of single and multivessel disease with global longitudinal strain

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The predictors of CAD were assessed with univariate and multivariate logistic regression analyses [Table 4]. Univariate analysis showed that among various parameters, only troponin and GLS were significantly associated with CAD (GLS: odds ratio= 0.033, P <0.001, [Table 4]). Multivariate analysis confirmed that GLS was an independent predictor of CAD.

Table 4: Univariate and multivariate logistic regression analyses of predictors of coronary artery disease

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The ROC curve analysis showed that GLS had an area under the curve (AUC) value of 0.869 for prediction of CAD (P <0.001, [Figure 1]). The optimum cutoff value was -17.70% with a sensitivity of 84%, specificity of 82%, positive predictive value of 82.4%, and negative predictive value of 83.7%. In comparison, the AUC for LVEF was 0.361.

Figure 1: ROC curver analysis for predictors of coronary artery disease. ECHO: Echocardiography, GLS: Global longitudinal strain, LVEF: Left ventricular ejection fraction, ROC: Receiver operating characteristic

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Discussion

In the present study, the mean age of the patients at presentation was 58.36 ± 11.21 years among cases and 56.54 ± 8.10 years among controls. In the study by Sarvari et al.,^[11] the mean age of the patients at presentation was 63.3 ± 9.3 years. Zhang et al.^[12] reported mean age of presentation of 60.2 ± 10.1 years in their study on association of GLS in NSTEMI patients. The patients' age ranged between 66 and 70 years in the other NSTEMI registries.^[13],[14] The age of the presentation was lower in the present study as compared to the above-mentioned studies. This difference in age may be due to higher prevalence of numerous risk factors such as hypertension, dyslipidemia, diabetes, truncal obesity, and many other genetic factors in the Indian population.^[15]

Raised levels of cardiac biomarkers indicate myocardial injury and help predict high-risk patients. Troponins are the best biomarker to predict short-term (30 days) outcome with respect to MI and death.^[16] In the present study, there was a statistically significant difference in serum troponin levels between the two groups. All patients among cases were found to be troponin positive, while only one patient had positive troponin test in the control group, which was due to myocarditis. There was a statistically significant inverse relationship between troponin positivity and GLS values. The patients with positive troponin assay had a lower mean GLS (−16.37 ± 1.5%) than those with negative troponin assay (−19.49 ± 1.38%). Similar results were found in the study done by Atici et al.^[17]

Univariate analysis showed that troponin level and GLS had a significant difference in the studied population. Multivariate analysis indicated that GLS was an independent predictor of CAD in patients with NSTEMI. Furthermore, GLS had significantly larger AUC for prediction of CAD, as compared to that of LVEF.

Eek et al.^[18] demonstrated that GLS values had better predictive values than LVEF and wall motion score index. D'Andrea et al.^[19] found that in patients with recent NSTEMI, longitudinal LV global and regional speckle-tracking strain measurements were powerful independent predictors of LV remodeling after reperfusion therapy. In a study done by Atici et al.,^[17] multivariate analysis indicated that GLS and the Global Registry of Acute Coronary Events (GRACE) risk score were independent predictors of CAD in patients with NSTEMI (GLS: odds ratio = 0.514, P < 0.001; GRACE score: odds ratio = 0.938, P = 0.007). GLS and territorial longitudinal strain assessments in this study demonstrated a statistically significant difference between CAD and control groups, with GLS values of − 16.27 ± 1.91% and − 18.74 ± 1.93%, respectively (P < 0.001). Liu et al.^[20] investigated the prognostic potential of layer-specific GLS in predicting cardiac events among NSTE-ACS patients with preserved LVEF. GLS for all three myocardial layers was reduced in patients with adverse outcomes (all P < 0.001). Our findings are consistent with those of the above-mentioned studies showing that in NSTE-ACS patients with preserved LVEF, GLS assessed at presentation has good ability to predict cardiac events, and may provide incremental prognostic information above the conventional echocardiographic risk factors.

As mentioned above, many studies have demonstrated that during myocardial ischemia, the function of subendocardial longitudinal fibers is impaired first, which occurs even before the ECG changes and symptom onset.^{[14],[21],[22],[23]} GLS detects these subtle changes in LV myocardial function better than a conventional echocardiogram. Our study reiterated the same findings. Moreover, we also found a positive correlation between troponin assay and GLS. This indicates that strain imaging is a useful tool to predict a high-risk patient compared to conventional echocardiographic measurements.

Study limitations

For this clinical study, 100 patients is a relatively small sample size, although it was sufficient for an adequately powered statistical analysis. Being a single-center study with a nonrandomized study design, our study had many limitations, and a larger study would be needed to confirm our findings. Moreover, ours was a case -control study. Such studies are susceptible to selection bias and the issues of reverse causality. Disease-specific quality of life of the patients was not assessed in this study. The limited timeframe for the study, and the extensive nature of the data collection needed could have perhaps resulted in missing some vital information. Also, the patients were evaluated only at one time point, and hence, repeat admissions were not assessed due to the limited tenure of this study. Treatment considerations were not part of the study; hence, improvement was not assessed. The treatment provided might have also varied among the patients, which we could not address in our analysis. Despite these shortcomings of the present study, the results clearly indicate that among patients presenting with suspected NSTEMI and inconclusive conventional electrocardiographic findings, GLS may help in risk stratification of the patients and may facilitate decisions regarding the early invasive strategy.

Conclusions

Risk assessment in NSTEMI is based on clinical evaluation, ECG, and biomarkers of myocardial damage but has its limitations. GLS assessment is a promising, easy-to-perform bedside imaging method for detection of subtle LV myocardial dysfunction. The present study demonstrates that GLS assessed using 2D-STE is superior to conventional echocardiography in excluding significant CAD in patients with suspected NSETMI. It can thus help in diagnosis and prognostication of these patients. Furthermore, GLS, when used in conjugation with other risk stratification strategies may be a powerful tool to identify high-risk patients and the best timing of reperfusion therapy in the NSTEMI population. However, well-designed controlled trials are needed to validate our findings before wider adoption of GLS for this purpose.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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