International Journal of Cardiovascular ResearchISSN: 2324-8602

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Research Article, Int J Cardiovas Res Vol: 5 Issue: 6

Echocardiographic Akinetic Areas As A Predictor Of Coronary Artery Disease In Heart Failure With Reduced Ejection Fraction: A Retrospective Study

Tiago Borges1*, Filipa Silva1*, Ana Ribeiro1, Raquel Mesquita1, João Carlos Silva2, Pedro Almeida2 and Paulo Bettencourt1
1Department of Internal Medicine, Centro Hospitalar de São João, Porto, Portugal
2Department of Cardiology, Centro Hospitalar de São João, Porto, Portugal
Corresponding author : Tiago Borges
Serviço de Medicina Interna, Centro Hospitalar de São João, E.P.E. Alameda Prof Hernâni Monteiro, 4200-319 Porto, Portugal
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E-mail: [email protected]
Received: May 11, 2016Accepted: July 25, 2016 Published: August 02, 2016
Citation: Borges T, Silva F, Ribeiro A, Mesquita R, Silva JC, et al. (2016) Echocardiographic Akinetic Areas as a Predictor of Coronary Artery Disease in Heart Failure with Reduced Ejection Fraction: A Retrospective Study. Int J Cardiovasc Res 5:6. doi: 10.4172/2324-8602.1000288

Abstract

Introduction: Coronary artery disease (CAD) is a major cause of heart failure with reduced ejection fraction (HFrEF). Current practice guidelines suggest that coronary angiography (CA) should be considered in patients with HFrEF without angina. Since echocardiography is a low cost, noninvasive, widely available imaging method we aimed to determine the association of regional wall motility anomalies with the presence and severity of CAD. Methods: We retrospectively identified consecutive patients submitted to coronary angiography in a Heart Failure (HF) clinic and with a technically satisfactory 2D echocardiography study. Patients with preserved ejection fraction and those reporting angina, with known CAD or submitted to coronary angiography for other purposes, were excluded. Demographic and echocardiographic variables, HF characteristics and angiographic data were abstracted from clinical records. Results: Of the 162 patients with HFrEF included, significant CAD was present in 37 patients and severe CAD in 18 patients. No correlation was found between the presence of regional wall motion abnormalities (RWMA) and significant CAD (p=0.48), but a significant association was present between akinetic areas and (significant or severe) CAD, which was also observed considering each of the three main coronary arteries. The calculated odd ratio of having CAD in the presence of akinetic areas was 7.0 (CI 2.8-17.7). Conclusion: In patients with HFrEF of unknown etiology, akinetic areas on echocardiogram are suggestive of an ischemic etiology. Our results support the performance of a CA in HFrEF with akinetic areas in the echocardiogram.

Keywords: Coronary artery disease; Coronary angiography; Echocardiography; Regional wall motion abnormalities

Keywords

Coronary artery disease; Coronary angiography; Echocardiography; Regional wall motion abnormalities

Introduction

Ascertaining myocardial ischemia as the major cause of heart failure (HF) has both therapeutic and prognostic importance [1].In fact, ischemic HF etiology has been shown to be independently associated with a worse long-term outcome and may benefit from coronary revascularization and secondary preventive measures [2,3].
The prevalence of clinically silent coronary artery disease (CAD) is high and current practice guidelines suggest that coronary angiography (CA) should be routinely considered in patients with heart failure with reduced ejection fraction (HFrEF) without a history of myocardial infarction (MI) or angina [4]. Although CA is associated with low risk of complications, those can be serious, and a noninvasive diagnostic approach may therefore be preferable, especially in patients without any chest pain [5].
Since echocardiography is a low cost, noninvasive, widely available imaging method we aimed to determine the association of regional wall motility anomalies with the presence and severity of CAD in patients with HFrEF without angina and no previous MI.

Methods

Patient selection
We retrospectively identified patients from a HF clinic, submitted to CA until the end of 2013 and with a technically satisfactory 2D echocardiography study. Exclusion criteria were HF with left ventricular ejection fraction >50%, a previous established etiology for HF, history of angina, already known CAD and indication for CA due to other purposes. The study protocol conforms to the ethical guidelines of the declaration of Helsinki and was approved by the local ethics committee.
Study design
Data collection included demographic variables, HF characteristics (NYHA classification and etiology), echocardiographic variables and angiographic data. HF was defined according to the European Society of Cardiology criteria [6].
A 2D echocardiography was performed in all patients with a standard apical and parasternal views using tissue harmonic imaging to assess regional wall thickening abnormalities and global left ventricular ejection fraction. Using the American Society of Echocardiography 16-segment LV model each segment was analyzed individually and scored on the basis of its motion and systolic thickening. The left ventricular regional wall was evaluated according to segment scores in which 1) was normal or hyperkinetic, 2) when there was a reduced systolic wall thickening (hypokinesis), 3) if there was a negligible thickening (akinesis) and 4) if there was a paradoxical systolic motion (dyskinesis) [7]. LV function was graded according to LV ejection fraction as normal (≥ 55%), mild (45–54%), moderate (36–44%) or severe (≤ 35%). The presence of diastolic dysfunction was defined as a E/e’ ratio >15. Mitral regurgitation was defined as mild (regurgitant orifice area <0.20 cm2), moderate (0.21–0.39 cm2) or severe (≥ 0.40 cm2). Left auricular dilatation was graded according to sex as mild (left auricular diameter - male 41–46 mm; female 39– 42 mm), moderate (male 47–52 mm; female 43-46 mm) and severe (male ≥ 53 mm; female ≥ 47 mm).
The angiographic data included the number of damaged arteries and corresponding narrowing quantitative degree of stenosis, in two orthogonal views with single observer reading. Significant CAD was defined as luminal diameter stenosis if at least 70% in at least one coronary artery. Severe CAD was defined as the presence of significant CAD of proximal left anterior descending coronary artery, threevessel CAD or two-vessel CAD involving the left anterior descending coronary artery [8].
Statistical analysis
Data storage and analysis were performed using SPSS version 21 (SPSS Inc, Chicago, IL, USA). Continuous variables are presented as mean ± standard deviation (SD) or median (interquartile range) if non-normally distributed. The categorical variables are presented as counts and proportions. Comparisons between groups of patients were made using χ2 test for categorical variables, independent samples t test for normally distributed continuous variables and Mann- Whitney U test when the distribution was skewed. The presence of significant CAD was analyzed both without and with adjustment for potential confounders, including the variables for which there was an imbalance between the two groups at baseline. The goodness of fit of the model was tested using the Hosmer-Lemeshow test. A p value of <0.05 was considered statistically significant.

Results

We included 162 patients with HFrEF in our study that met the abovementioned criteria, among which 37 patients had significant CAD and 18 patients severe CAD. Patient characteristics including echocardiographic variables are shown in Table 1. In the group of patients with severe CAD, significant CAD of proximal LAD artery was present in two cases, two-vessel CAD involving LAD in seven cases and three-vessel CAD in nine cases.
Table 1: Echocardiographic variables.
Significant age differences were found between patients with and without CAD (p<0.01 for both significant and severe CAD). No correlation was found between the presence of regional wall motion abnormalities (RWMA) and significant CAD (p=0.48). However, the discrimination of RWMA in hypokinesis, akinesis and dyskinesis revealed a significant association between akinetic areas and (significant or severe) CAD and these differences were confirmed for each of the three main coronary arteries (Table 2).
Table 2: Presence of significant CAD (≥ 70% stenosis) of the three main arteries according to the presence of regional wall motion abnormalities.
The calculated odd ratio of having CAD in the presence of akinetic areas was seven times higher than in their absence (OR 7.0; 95% CI 2.8-17.7). In the case of the presence of hypokinesis and dyskinesis the odd ratio was 0.7 (95% CI 0.3-1.6) and dyskinesis 2.9 (95% CI 0.7-11.4), respectively. There was a significant correlation between increasing age and the presence of akinetic areas (p<0.01), but the logistic regression including both variables (Hosmer and Lemeshow test, p=0.83) showed that akinetic areas (p<0.01), but not age, (p=0.13) was associated with the presence of significant CAD.

Discussion

Our results show that in HFrEF and no previous known CAD, akinetic areas on echocardiogram point to an ischemic etiology. Dysmotility of ventricular walls has been associated with CAD [9]. However, this association is not consistent with our results: instead, the presence of akinetic (but not hypokinetic) areas appears to be associated with CAD. Not only there was a significant association with the presence of akinetic areas, but also significant associations were found for each of the three main coronary arteries. Our results, due to a limited number of patients presenting with dyskinetic areas, cannot draw conclusions about whether this pattern may be associated with CAD.
RWMA of left ventricular contraction are a hallmark of CAD and the utilization of a fixed external-axis system has been preferred for localizing contraction defects [10]. Moreover, endocardial wall motion appears to be more affected by myocardial infarction than wall thickening [11]. In a previous study, the presence of RWMA had a sensitivity of 83%, a specificity of 57% and a predictive accuracy of 77% in detecting CAD in patients with dilated cardiomyopathy [12]. There is a relationship between regional myocardial blood flow and regional left ventricular systolic function, making it logical to evaluate left ventricular regional wall motion during ischemia according to segment scores [7]. In this context, echocardiography combined with dobutamine infusion is seen as an accurate method for detecting CAD and predicting its extent in those with localized rest RWMA [13]. Nevertheless, it is known that RWMA may occur in the absence of CAD, such as in left bundle branch block, myocarditis, sarcoidosis and stress-induced cardiomyopathy, so the relationship mentioned above is not straightforward [14]. Our study suggests that, among left ventricular RWMA, at least one pattern (akinesis) is specific of CAD.
When HFrEF patients present without angina and no previous myocardial infarction, the search for an etiology may be very challenging. Coronary angiography continues to be the gold standard for the assessment of CAD severity and some authors argue in favor of routine catheterization, since the prevalence of clinically silent CAD is high [15]. In order to optimize the diagnostic accuracy of coronary catheterization, a clinical tool was recently developed to predict the absence of CAD in patients with HFrEF of unclear etiology: diabetes, electrocardiographic Q waves or left bundle branch block and ≥ 2 nondiabetes cardiovascular risk factors (age, dyslipidemia, hypertension and tobacco use) were considered to be independent predictors of severe CAD and the presence of at least one variable identified 97% of the patients with CAD and all of those with severe CAD [16]. However, no echocardiographic variables have been considered in this score. Our result suggest that it would be reasonable to incorporate akinetic areas in the assessment of these patients, since echocardiography is a widely available imaging method, with less costly than magnetic resonance imaging and is the most used imaging for definition and stratification of HFrEF patients during the initial work-up study.
Many limitations of this study are the consequence of its retrospective nature. Besides, it was single center study with a small sample size, submission to angiography was at physicians’ discretion (not allowing to authentically document sensitivity and specificity) and CAD was established with basis on patients’ symptoms and history of myocardial infarction. The relative young age of our patient population may also limit the generalization of results, although CAD prevalence would be expected to be higher. Significant age differences were found between patients with and without akinetic areas (p<0.01), which also raise the possibility of that these RWMA may be associated with the ageing process. One should also notice that there are currently other means of looking for CAD in patients with systolic HF and low pre-test probability of CAD, e.g. computed coronary angiography. Furthermore, the location of coronary stenosis has not been discriminated and the import of distal stenosis cannot be equated with proximal ones.
In the future, it would be interesting to acknowledge if the localization of akinetic areas corresponds to stenosis in the coronary arteries that are expected to irrigate the areas where those dysmotility patterns are found, despite extreme variability in coronary blood supply to myocardial segments. This variability might be explained by anatomic variations and is more unpredictable in the apical cap. According to the 17-segment model that derived from the 16-segment model for left ventricle segmentation recommended by the American Society of Echocardiography in 1989, segments 1, 2, 7, 8, 13, 14 and 17 are often assigned to the left anterior descending coronary artery, segments 3, 4, 9, 10 and 15 to a dominant right coronary artery, and segments 5, 6, 11, 12 and 16 to left circumflex artery [17,18].
In conclusion, the presence of akinetic (but not hypokinetic) areas may predict CAD, while the absence of hypokinetic areas does not exclude CAD. The inclusion of akinetic areas, more than RWMA, may be useful in optimizing the accuracy of clinical tools that predict CAD in HFrEF patients and optimize the diagnostic yield of coronary angiography in this population.

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