Does EPSS measurements obtained by ED physicians correlate with calculated LVEF from comprehensive transthoracic echocardiography (TTE)?

Can certain EPSS cutoff values be used to predict systolic dysfunction? 

What is the relationship between bedside visual estimates of global cardiac function (GCF) and the calculated LVEF measurements?

• Design 

This was a prospective observational trial.

• Population 

A convenience sample of 80 hospitalized patients undergoing comprehensive TTE for any indication. Subjects were recruited between February and April 2012 from an academic level I trauma center. Exclusion criteria were known pregnancy or age less than 18 years.

• Intervention 

Three emergency ultrasound fellows performed bedside 4-view basic echocardiographic examinations consisting of subxiphoid, parasternal long, and parasternal short and apical views and made estimates of GCF. The fellows then obtained separate parasternal long-axis views and performed M-mode measurements of the EPSS. Comprehensive TTE was separately performed by cardiac sonographers and LVEF was calculated via the Teichholz method.

• Outcomes  

• • Subjective estimates of GCF categorized as normal systolic function (LVEF > 55%), moderate systolic dysfunction (30% > LVEF > 55%), or severe systolic dysfunction (LVEF < 30%)
  • EPSS measurements
  • Calculated LVEFs also categorized as normal/moderate/severe as above

Calculated LVEF ranged from 13%-86%. EPSS ranged from 0.50-29.70 mm.

Men had higher EPSS scores and higher calculated estimates of LVEF. No other demographic or clinical variables were identified as potential covariates. 

The linear regression model revealed that EPSS is a statistically significant predictor (P < .001) of calculated LVEF.

An EPSS measurement of greater than 7 mm was 100% sensitive and 51.6% specific for severely reduced LVEF. An EPSS measurement of greater than 8 mm was 83.3% sensitive and 50.0% specific for any systolic dysfunction.

Estimated GCF and calculated LVEF were in agreement in 49 (69.0%) of subjects with a weighted Cohen κ of 0.58, with strongest agreement for subjects with severe systolic dysfunction.

Strengths:

This study is the first to demonstrate that EPSS can provide a quantitative prediction of LVEF. One strength of this study is the generalizability of the findings given that all indications for TTE were included. Another strength is that the ED ultrasound fellows and cardiac sonographers performed their studies independently, unlike a prior study that utilized the same scans performed by residents to obtain both EPSS and LVEF. 

Limitations:

There were possible misestimations of EPSS in certain pathologic states, such as overestimation of EPSS in mitral stenosis. Additionally, this paper describes the Teichholz method, which is subject to inaccuracies, especially in states of dyskinesis. Of note, the Teichholz method has since been supplanted by the modified Simpson’s rule and is no longer used clinically. On average, time from EPSS measurement to comprehensive echocardiogram was 6 hours with the possibility that systolic function changed during that window of time. Finally, the study size was fairly small with 71 subjects included in the final analysis.

ED physicians can assess left ventricular systolic function using the EPSS, and EPSS is strongly correlated with calculated LVEF. An EPSS greater than 7 mm may be used to predict patients with severely reduced LVEF. ED physician visual estimation was less effective and less consistent than EPSS measurement for predicting systolic function.

We agree that EPSS is a feasible and useful tool for assessing systolic function at the bedside. This study establishes that a 7 mm EPSS cutoff is highly sensitive for detecting severe systolic dysfunction. The clinical utility of an EPSS cutoff of 8 mm for any systolic dysfunction is less clear. Employing EPSS measurement with the 7 mm cutoff in mind, in conjunction with visual estimation by an experienced ED sonographer, is likely to provide a more complete picture of a patient’s systolic function at the bedside prior to obtaining a formal echocardiogram.

This post was written by Jennie Xu, MS4 at UCSD School of Medicine, Charles Murchison, MD and Amir Aminlari, MD. 

McKaigney CJ, Krantz MJ, La Rocque CL, Hurst ND, Buchanan MS, Kendall JL. E-point septal separation: a bedside tool for emergency physician assessment of left ventricular ejection fraction. The American Journal of Emergency Medicine. 2014 Jun 1;32(6):493-7.

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   4. Massie BM, Schiller NB, Ratshin RA, Parmley WW. Mitral-septal separation: new echocardiographic index of left ventricular function. The American journal of cardiology. 1977 Jun 1;39(7):1008-16.