Canadian Health and Care Mall: Mitral Valve E-Point Septal Separation as an Indicator of Ejection Fraction

The mitral valve E-point septal separationThe mitral valve E-point septal separation (EPSS) is widely used clinically as an M-mode echocardio-graphic indicator of a normal or abnormal left ventricular ejection fraction. However, no study has examined systematically the utility of the EPSS in predicting normality of ejection fraction in patients with reversed septal motion which is often observed in patients with right ventricular volume overload states or right ventricular disease (either primary or due to pulmonary disease). If valid, this measurement would have significant clinical importance because other conventional M-mode echocardiographic correlates of ejection fraction, such as fractional shortening, are not useful in patients with reversed septal motion. Therefore, the purpose of this study was to compare the utility of the EPSS as an indicator of a normal or abnormal ejection fraction in patients with normal and reversed septal motion.

Patient Population

Two groups of patients were studied retrospectively. No patient in either group had aortic regurgitation or mitral stenosis.

Group 1 comprised 103 patients with normal or decreased septal motion by M-mode echocardiography. This group comprised all patients seen in our echocardiographic laboratory over an 18-month period who also had their left ventricular ejection fraction measured independently by first pass radionuclide angiography. The group consisted of 57 men and 46 women. Their mean age was 48 years.

Group 2 was made up of 27 patients with reversed septal motion on their M-mode echocardiograms examined in our laboratory over this same time period who also underwent first pass radionuclide angiography. The clinical diagnosis in these 27 patients included a dilated cardiomyopathy with biventricular failure in 12, right ventricular volume overload state in eight, conduction delay or permanent pacemaker in five, myocardial infarction in one, and pericardial effusion in one. There were 12 men and 15 women with a mean age of 55 years. Twenty-two patients were in sinus rhythm, three were in atrial fibrillation, and two had electronic ventricular pacers.pericardial effusion

Methods

All subjects underwent standard M-mode echocardiography in the left lateral decubitus position using commercially available equipment (3.0 mHz transducer). The EPSS was measured using leading edge methodology. This distance was defined as the vertical distance from the most posterior motion of the interventricular septum to the mitral valve E point in the same cardiac cycle (but not necessarily at the same point in time) as previously described (Fig 1). Ready to read more – interesting facts on delicious official group – Canadian Health and Care Mall.

Left ventricular ejection fraction was measured independently by first pass radionuclide angiography performed in the 30° right anterior oblique position following the rapid intravenous injection of a 1.0 mCi bolus of “Tc pertechnetate, utilizing techniques previously described from this institution. The echocardiographic and radionuclide studies were performed within 14 days of one another. All patients were clinically stable without change in symptoms, physical examination, or medication during the study period.

Correlation coefficients between ejection fraction and the EPSS were tested according to standard least squares linear regression formulae. Predictive values were calculated according to standard formulae.

Results

In group 1, the patients with normal or reduced septal motion, the EPSS ranged from 0 to 32 mm and the left ventricular ejection fraction varied from 15 percent to 85 percent. There was a significant negative correlation between EPSS and ejection fraction (r= —0.79, p<0.001) (Fig 2). In this group, the predictive accuracy of an EPSS = <5 mm indicating a normal ejection fraction (>50 percent) was 0.75. The predictive accuracy of an EPSS >10 mm indicating a reduced ejection fraction was 0.95. Values for EPSS between 5 and 10 mm were less predictive (Table 1), but were most often associated with a reduced ejection fraction.

In group 2, the group with reversed septal motion, the range in EPSS was 0 to 28 mm and the ejection fraction was between 14 percent and 75 percent. The correlation coefficient between EPSS and ejection fraction was —0.87 (p <0.001) (Fig 3). The predictive value of an EPSS = <5 mm predicting a normal ejection fraction in this group was 0.80 and the predictive value of an EPSS >10 mm predicting an abnormal ejection was 0.94. As with group 1, EPSS values between 5 and 10 mm were less reliable predictors of ejection fraction (Table 1), but also tended to indicate a reduced ejection fraction.

Discussion

The mitral valve E-point septal separation has attained wide clinical usage since the initial report of Massie et al. Although some studies have failed to find a close correlation between the EPSS and ejection fraction, most authors agree that the EPSS is a valid clinical indicator of the presence of a normal or abnormal left ventricular ejection fraction so long as patients with mitral stenosis and aortic regurgitation are excluded. Although two-dimensional echocardiography has been shown to measure accurately the left ventricular ejection fraction, this modality and the technology required for the routine measurement of ejection fraction are not yet widely available, and M-mode echocardiography continues to be a widely applied diagnostic modality. The utility of the EPSS measurement has been in the rapidity and ease of measurement, and the predictive accuracy of an abnormal value.

It would be especially useful if the EPSS correctly predicted a normal or abnormal ejection fraction in patients with reversed septal motion because other standard M-mode echocardiographic measurements such as fractional shortening or left ventricular volume estimates have been found to be less useful in the presence of reversed septal motion. In the present study, the patients with reversed septal motion demonstrated a weak correlation (r = 0.55, p<0.05) between fractional shortening and radionuclide ejection fraction, confirming the previous reports.

To our knowledge, no study has systematically examined the utility of the EPSS as an indicator of ejection fraction in patients with reversed septal motion. Massie et al included five patients with reversed septal motion in their series of 125 patients evaluated with biplane cineangiography and found the EPSS predictive of ejection fraction in the four patients with an atrial septal defect. Lew et al also included seven patients with reversed septal motion in their report of the utility of EPSS in 73 patients with myocardial infarction. The correlation between EPSS and ejection fraction in their group of seven patients did not attain significance (r = 0.50, p>0.20) due to the small sample size, but the linear regression line (у = 0.34x-I-21) is very similar to the present study.

myocardial infarctionIn this study, we found that the EPSS correlated with left ventricular ejection fraction equally well in the patients with reversed septal motion of diverse etiologies and in the group with normal septal motion. Indeed, the slopes of the linear regression lines in the two groups were nearly identical, as were the predictive values of a normal and abnormal EPSS. Although the group of patients with reversed septal motion was too small to subset systematically by disease category, the EPSS predicted ejection fraction similarly in all the disease entities examined in this study.

In the group of patients with reversed septal motion, an EPSS <5 mm was highly predictive of a normal ejection fraction. This finding is consistent with the data of Massie et al1 who also found an EPSS <5 mm to be predictive of a normal ejection fraction. In the present study, values of EPSS between 5 and 10 mm were associated with reduced ejection fractions in most cases, but with a lower predictive accuracy than an EPSS >10 mm, which was highly predictive of a reduced ejection fraction. Indeed, in the group with reversed septal motion, there was only one patient with an EPSS <5 mm whose ejection fraction was <50 percent. This patient had an EPSS of 1 mm and a radionuclide angiographic ejection fraction of 35 percent. However, this patient had severe pulmonary hypertension, and it is possible that the radionuclide angiographic ejection fraction in this patient may have been in error due to prolonged pulmonary transit of the radioisotope.

In this study, as in previous reports, the linear correlation coefficient between EPSS and ejection fraction was highly statistically significant for the groups with normal and reversed septal motion. However, in both groups, the scatter of individual data points (Fig 2 and 3) clearly indicates that a specific value for ejection fraction cannot be inferred accurately from the EPSS value. Thus, the utility of the EPSS lies in the ease of measurement and the accuracy with which a normal or abnormal ejection fraction can be predicted.

Conclusions

In this study, we examined the utility of the mitral valve EPSS as an M-mode echocardiographic indicator of a normal or abnormal left ventricular ejection fraction in patients with reversed septal motion on their M-mode echocardiogram. This study demonstrated that the EPSS is as accurate an indicator of ejection fraction in reversed as in normal septal motion. The correlation coefficient and slope of the regression lines are nearly identical for normal or reversed septal motion, and the predictive values of a normal EPSS and an abnormal EPSS are nearly identical for the two groups. An EPSS <5 mm is highly predictive of a normal ejection fraction, and an EPSS >10 mm is even more predictive of a reduced ejection fraction. The EPSS is a valuable clinical predictor of a normal or depressed ejection fraction regardless of abnormalities of septal motion.

Figure-1

Figure 1. An M-mode echocardiogram of a patient with reversed septal motion demonstrates the measurement method described in the text. Note that the most posterior motion of the septum does not occur at the time of the E-point. The time lines are at 1-second intervals and the depth markers are at 2 mm intervals. E is mitral valve E-point; S, most posterior motion of the interventricular septum.

Figure-2

Figure 2. Comparison of EPSS with radionuclide angiographic ejection fraction in patients with normal or depressed septal motion. Note the significant correlation, although there is scatter of individual points. Note also that an EPSS <5 mm is highly predictive of a normal ejection fraction and an EPSS >10 mm is more highly predictive of an ejection fraction <50 percent. The solid line represents the linear regression line.

Figure-3

Figure 3. Comparison of EPSS with radionuclide angiographic ejection fraction in patients with reversed septal motion. Note that the correlation coefficient, linear regression line and predictive values are nearly identical to the patients with normal septal motion depicted in Figure 2. The solid line represents the linear regression line.

Table I—Values for EPSS

EPSS (mm) Normal Septal Motion (No. of Patients) Ejection Fraction Reversed Septal Motion (No. of Patients) Ejection Fraction
<50% >50% <50% >50%
+ <5 6 18 1 4
6-10 16 7 4 2
>10 54 3 15 1
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