Introduction: Measurement of the left ventricular ejection fraction (LVEF) is a common tool for evaluating the left ventricle (LV) systolic function. The aim of this study was to evaluate and compare the LVEF and mitral regurgitation (MR) severity as estimated by angiography and echocardiography in patients with coronary artery disease (CAD) and LV systolic dysfunction. Methods: In this observational study, 39 men and 11 women at a mean age of 60 years were recruited. The patients underwent catheterization and echocardiography, and the data on the LVEF and MR by both methods were registered. Results: The mean LVEF by echocardiography and angiography was significantly correlated (correlation coefficient = 0.698; P < 0.0001). Although there was agreement between these methods in the estimation of the mean EF (mean difference in the LVEF = 1.23 ± 7.63% and 95% limit of agreement = −12.5–19) and the κ coefficient was 45.7% (P = 0.001), the estimated mean EF was 32.6 ± 10.25% by echocardiography and 29.8 ± 8.2% by angiography (P = 0.007). Furthermore, there was a statistically significant difference in the estimated MR severity between the two methods (P = 0.0001), with echocardiography reporting higher degrees of severity than angiography. Conclusions: In our patients with CAD and LV systolic dysfunction, after the exclusion of age, sex, number of diseased coronary arteries, and myocardial infarction history from the analysis, although the mean LVEF by echocardiography and angiography was significantly correlated, echocardiography estimated higher LVEF values than angiography, especially in the patients with triple-vessel disease. Moreover, echocardiography showed higher degrees of MR severity than angiography.
Keywords: Angiography, echocardiography, left ventricular ejection fraction, mitral regurgitation severity
|How to cite this URL:|
Mirdamadi A, Tavakolifard N, Ebrahimi E. Left ventricular ejection fraction and mitral regurgitation assessment: A comparison study between echocardiography and angiography. Arch Cardiovasc Imaging [Epub ahead of print] [cited 2018 Dec 14]. Available from: http://www.cardiovascimaging.com/preprintarticle.asp?id=238935
| Introduction|| |
Coronary artery disease (CAD) is one of the most common heart diseases and is responsible for the highest mortality rates in developed and developing countries. Likewise in Iran, changes in the structure of society in terms of urbanization, industrialization, and population growth have contributed to the rise in the rank of CAD as the most frequent noncommunicable disease and the principal cause of death.,,
Systolic performance evaluation of the left ventricle (LV) is critical in the efficient management of patients with different kinds of CAD. Estimation of the left ventricular ejection fraction (LVEF) is the most common method for this purpose.,
There are large numbers of diagnostic imaging methods for the evaluation of the LVEF such as echocardiography, angiography with contrast ventriculography, angiography with radionucleoside, and cardiac magnetic resonance imaging (MRI).
MRI is widely deemed the gold standard method for calculating the LVEF and the LV volume, although this technique is not applicable in patients with pacemakers and defibrillators. Nonetheless, aside from the relatively high costs, data processing in MRI is also time-consuming.
Use of echocardiography as a diagnostic tool is gaining more popularity among cardiologists on the strength of its user-friendliness, noninvasiveness, cost-effectiveness, repeatability, and safety.
Echocardiography, widely regarded as the most common method for calculating the EF, provides important information about prognosis in patients with CAD.
It is employed to evaluate the LV shape, the inner diameter and volumes of cardiac cavities, and the global and local systolic and diastolic LV functions. Another advantage of echocardiography is its ability to measure both the wall thickness and the LV muscular mass.
While heart catheterization and coronary angiography are performed, the EF is evaluated through ventriculography. Ventriculography is a method for evaluating the EF and the severity of mitral regurgitation (MR). Some cardiologists and cardiac surgeons tend to base their treatment strategy on angiographic data. Evaluation of the EF in angiography is accompanied by some pitfalls such as extrasystoles, which occur during ventriculography and interfere with cardiac contractions. Moreover, the amount of the contrast material used during ventriculography can significantly change the results. In light of the above evidence, we sought to compare the EF measured by ventriculography conducted through the angiographic method and the EF measured by echocardiography.
| Methods|| |
The present observational study was conducted from 2014 to 2015 in the Iranian city of Isfahan by recruiting patients with CAD and LV systolic dysfunction. The patients were recruited from three major heart centers in Isfahan, namely, Chamran Hospital (a public heart center), Sina Hospital (a private heart center), and Shariati Hospital (a hospital run by the Iranian Social Security Organization). Patients candidated for coronary revascularization through coronary artery bypass grafting or percutaneous coronary intervention were participated in this study. The study protocol was approved by the institutional ethics committees of the aforementioned hospitals and written informed consent was obtained from the whole study population. The inclusion criteria comprised having CAD and LV systolic dysfunction. Sampling was done through the convenience method. Fifty patients who met the inclusion criteria were selected and, on the basis of their angiography results, were categorized as having single-, double-, and triple-vessel disease. Thereafter, all the 50 patients underwent a full echocardiography study by a fellow of echocardiography, who determined the EF and MR severity in each patient. The echocardiography studies were mostly performed during a 2-week period after angiography. The interval between angiography and echocardiography did not exceed 1 month and any cardiac events during this period or other conditions which could change the LVEF or MR severity led to the exclusion of the patient from the study. The angiography films were studied separately by two cardiologists, who were blinded to the echocardiography results. The cardiologists' estimations of the EF and MR severity of each patient were recorded in a blind manner.
Echocardiography was conducted for all the patients with a vivid three echocardiography machine (GE Healthcare, US). The views applied in the calculation of the systolic and diastolic LV functions as well as the estimation of MR severity were all standard views such as the parasternal long-axis and short-axis, apical long-axis, and four- and two-chamber views in accordance with the guidelines of the American Society of Echocardiography. Suspicious echocardiographic findings were confirmed through 3D echocardiography using an iE 33 Philips machine (Philips Medical Systems, Bothell, WA, USA).
An invasive method for the evaluation of the LV, angiography is carried out in the catheterization laboratory. In the present study, angiography was performed through the transfemoral approach by puncturing the skin at the groin site and passing a pigtail catheter through the femoral artery and the aorta before crossing it through the aortic valve and into the LV. Afterward, ventriculography was done with the injection of 30 to 50 cc of the contrast medium through the pigtail catheter, under fluoroscopy. All the ventriculography procedures were done in the right anterior oblique view, and they showed the LV ventricular systolic function, MR, and other abnormalities of the LV.
The statistical analyses of the data were performed using SPSS 22 for Windows (SPSS Inc., Chicago, Illinois, USA), and statistical significance was set at a P = 0.05.
The collected data were processed with descriptive measures (means ± standard deviations [SDs] and medians with ranges). Paired t-tests were applied to compare the estimated EF between the two methods of angiography and echocardiography. The Pearson correlation coefficient was drawn upon to assess the strength of the association between the EF by echocardiography and the EF by angiography. Correlations were considered poor if r was <0.25, fair if r was between 0.25 and 0.50, moderate to good if r was between 0.50 and 0.75, and good to excellent if r was >0.75. The effects of other factors on the relationship between the EF by angiography and the EF by echocardiography were adjusted utilizing linear regression analysis. The agreement between angiography and echocardiography was evaluated using the Bland–Altman diagram.
| Results|| |
Fifty patients, comprised 39 men and 11 women at a mean ± SD age of 60 ± 9.6 years, participated in the present study. Of this total, 46 (92%) patients had a history of myocardial infarction (MI) and 4 (8%) patients had no such history. Single-, double-, and triple-vessel diseases were reported in 6 (12%), 7 (14%), and 37 (74%) patients, correspondingly.
Left ventricular ejection fraction assessment
The estimated mean EF was 32.6 ± 10.25 by echocardiography and 29.8 ± 8.2 by angiography; this difference was statistically significant (P = 0.007). The estimated mean EF by echocardiography and angiography according to age groups is listed in [Table 1].
|Table 1: Mean ejection fraction by echocardiography and angiography according to age groups in the study population (n=50)|
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The mean EF by echocardiography with a correlation coefficient of 0.693 was significantly correlated with the mean EF by angiography (P < 0.0001). The relationship between these two methods in estimating the EF is illustrated in [Figure 1].
|Figure 1: Correlation for LVEF determined by angiography and echocardiography (n = 50). LVEF: Left ventricular ejection fraction|
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The mean EF for the male patients was estimated to be 31.46 ± 9.72 by echocardiography and 30.44 ± 8.3 by angiography, with the difference constituting statistical significance (P = 0.01). The mean EF for the female patients was estimated to be 36.64 ± 11.51 by echocardiography and 33.7 ± 10.9 by angiography; this difference in the estimation of the EF was not statistically significant (P = 0.314).
The mean EF by echocardiography and angiography based on the patients' number of diseased coronary arteries is depicted in [Table 2].
|Table 2: Mean ejection fraction estimated by echocardiography and angiography based on the number of diseased coronary arteries|
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The mean EF in the patients with a history of MI was estimated to be 32.6 ± 9.6 by echocardiography and 29.8 ± 7.9 by angiography, and this difference was statistically significant (P = 0.009). In the patients without a history of MI, the mean EF was estimated to be 32.2 ± 18 by echocardiography and 29.7 ± 12.5 by angiography, with the difference failing to constitute statistical significance (P = 0.547).
The mean EF estimated by echocardiography was higher than that by angiography: the mean difference in the LVEF was 1.23, the SD of the difference was 7.63, and the 95% limit of agreement (mean ± 2 SD) was 14.03–16.49 (Bland–Altman range = 30.52%) [Figure 2]. The difference in the value of the LVEF by the two methods of echocardiography and angiography was negative at the lowest EF values and positive at the highest values [Figure 2]. The agreement between echocardiography and angiography in calculating the different degrees of the EF (EF <45) was about 45.7% (κ = 0.457 and SE = 0.229; P = 0.001), indicating that the agreement rate was moderate.
|Figure 2: Bland–Altman plot of the measurement of the LVEF by echocardiography versus angiography in the study population (n = 50). LVEF: Left ventricular ejection fraction|
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Assessment of mitral regurgitation severity
There was a statistically significant difference in the severity of MR as reported by angiography and echocardiography (P < 0.0001) [Table 3]: Echocardiography showed higher degrees of MR severity than angiography. The degree of agreement between the 2 methods in calculating different degrees of MR severity was about 3% (κ = 0.038 and SE = 0.04; P = 0.349), indicating that the agreement rate was low.
|Table 3: Results of mitral regurgitation severity reported by echocardiography and angiography in the study population (n=50)|
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The linear regression analysis of the EF by echocardiography and the EF by angiography once adjustments were made for age, sex, MI history, and number of diseased coronary arteries (≥1 vessel) showed that the two estimations were still correlated [Table 4].
|Table 4: Results of the multiple linear regression analysis for the echocardiographic ejection fraction as a dependent factor|
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| Discussion|| |
One of the basic assessments of patients with CAD is the evaluation of the LV output and the LVEF. Our results revealed a statistically significant difference between the mean EF by echocardiography and that by angiography, with echocardiography reporting higher average EF values than angiography (P > 0.001). This finding chimes in with the results of a study by Bellenger et al. in England and a study by Soroor-Azimzadeh and Shamsadini  in Iran. The low estimated EF value by angiography in comparison with that by echocardiography may be related to the injection of the contrast medium into the coronary arteries during angiography which may cause transient ischemia in the myocardium and result in a lower estimation of the EF by angiography.
In the current study, the correlation in the mean EF between the two methods of echocardiography and angiography was moderate to good (r = 0.698 and P < 0.0001) which is concordant with the results of the studies by Soroor-Azimzadeh and Shamsadini  in Iran, Gimelli et al., and Garg et al. (r = 0.7). In contrast, our result is not in line with the finding of a study by Bellenger et al. (r = 0.46).
The total range of agreement between the two methods in our study was 30.52%, in contrast to the result in the study by Bellenger et al., who reported a range of 39%. This disparity between our results can be due to the difference in the type of study participants, whereas our study was carried out on patients with CAD, Bellenger et al. evaluated patients with chronic heart failure.
In our study, angiography showed that 92% of the patients had EF values <45% and the agreement rate between angiography and echocardiography was moderate (≃46%). In contrast, Gimelli et al. reported that the agreement rate between the two methods was appropriate and around 76%. The discrepancy in our studies vis-à -vis the agreement rate between the two methods may be in consequence of a high percentage of patients with EF values below 45% in our study in comparison with the study by Gimelli et al. (92% vs. 32%). This indicates that in patients with lower EF values, there is a more pronounced reduction in the agreement rate between echocardiography and angiography.
We found that the mean EF by echocardiography, taking into account the number of diseased coronary arteries in all the patients, was higher than the mean EF by angiography. Nevertheless, this difference was statistically significant only in the patients with triple-vessel disease. Triple-vessel disease was reported in 37 (74%) of our patients, while single-and double-vessel diseases were reported in only 13 (26%) patients. The small number of patients with single- or double-vessel disease may have resulted in the absence of a statistical significance in the EF measurement between the two methods. Accordingly, we would suggest that future investigations be conducted on larger sample sizes of patients with CAD.
We detected no significant correlation in MR severity between angiography and echocardiography, and the difference between these two methods was statistically significant (P < 0.0001). It seems that the recent advances in the technology of echocardiography have enabled this method to detect less severe MR or even very subtle cases better than angiography. Indeed, angiography for the precise evaluation of MR severity is highly dependent on the volume of the contrast medium, fluoroscopic viewing angle, and absence of extrasystoles during ventriculography. Extrasystoles are common during ventriculography and are secondary to forceful injections of contrast media into the LV.
In a study carried out by Uretsky et al. in 2015, a weak correlation was seen between the two methods of echocardiography and MRI in the estimation of MR severity (r = 0.4 and P < 0.0001). Fehmi et al. also reported no concordance between echocardiography and angiography in the estimation of MR severity and concluded that eccentric MR jets constituted the most likely reason for the discrepancy between Doppler techniques and ventriculography. Eccentric MR is a chief cause of the misdiagnosis of MR severity in cardiology. Nowadays, advanced echocardiography machines outfitted with new Doppler technology enable physicians to better detect eccentric MR. Transesophageal echocardiography and cardiac MRI are, however, more suitable ways for the precise detection of eccentric MR.
After we had made adjustments for factors such as age, sex, MI history, and CAD in the regression model, we found that the correlation between echocardiography and angiography regarding the estimation of the EF was still statistically significant. This finding indicates that in patients with CAD and a history of MI, regardless of their gender and age, the estimated EF by echocardiography and angiography will be very similar.
One of the limitations of the current study was our insufficient fund to compare the EF results between echocardiography and MRI as the gold standard method for the estimation of the EF. Therefore, we would recommend that further research is undertaken to compare the EF by echocardiography and that by MRI. Our results demonstrated that the LVEF values by echocardiography were significantly higher than those by angiography. Furthermore, echocardiography reported higher degrees of MR severity than angiography, with the difference between the two methods constituting statistical significance.
| Conclusions|| |
In our patients with CAD and LV systolic dysfunction after the exclusion of age, sex, number of diseased coronary arteries, and MI history, echocardiography reported higher EF and MR severity values than angiography.
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Conflicts of interest
There are no conflicts of interest.
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Department of Heart, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan
Source of Support: None, Conflict of Interest: None
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[Table 1], [Table 2], [Table 3], [Table 4]