A guest post by Dr. Andrew Kirkpatrick (@AskEMdoc), an Emergency Medicine resident at the University of Texas Medical School at Houston.
With all of the recent advancement in the field of Emergency Department (ED) ultrasound, you may be tempted to think Emergency Physicians are masters of the bedside cardiac ultrasound and the assessment of systolic heart failure. Despite the misleading title, the results of this article would suggest that is not the case.
This is a prospective observational study to determine if E-point Septal Separation (EPSS) measurements made by emergency physicians correlated with calculated Left Ventricular Ejection Fraction (LVEF) measured by cardiologist using comprehensive Trans-Thoracic Echocardiography (TTE). Cardiac ultrasound and TTE were performed on 80 patients between the ages of 22 and 100 years old, of which 71 were included in the final analysis. The study took place in the academic setting of Denver Health, conducted by 3 ultrasound fellows who had done at least 100 ultrasound scans. They were given a 10 minute didactic presentation and supervised doing 3 EPSS measurements before they were set loose in the hospital to find patients who had undergone TTE in the last 24 hours.
Based on their results, the authors conclude that an EPSS of greater than 7mm is ideal for diagnosing severely reduced LVEF (<30%), with a sensitivity of 100% and a specificity of 51%. This suggests EPSS is only useful in ruling out severe systolic heart failure – as values over 7mm were poor predictors of actual LVEF. This inability to provide predictive information is well demonstrated by Figure 2, in which there are 3 patients with EPSS clearly in the range associated with severe systolic dysfunction- 20-22mm – and 2 of these 3 had normal ejection fraction on formal echocardiography. Put another way, only 31 of the 63 patents with EPSS >7mm had moderate heart failure, calling into question the author’s suggestion the EPSS is a tool to accurately assess for LVEF. In addition to the previous findings, the authors find that an EPSS of >8mm is a poor predictor of any systolic dysfunction with a sensitivity and specificity of 83.3% and 50.0%, respectively. The authors also assessed the ability of emergency physicians to visually estimate ejection fraction, and found generally poor correlation with echocardiography and only fair interobserver reliability.
There are several problems with this paper. The sample size was small, and generalizability to Emergency Department patients may be limited because a majority of the population studied was inpatient. More importantly, three ED ultrasound fellows performed all of the EPSS measurements. These physicians having a special interest in ultrasound are likely more adept at wielding an ultrasound than the average emergency physician. At best, this article makes a weak case for the clinical relevance of EPSS. And, ultimately, subtle systolic dysfunction that may or may not be picked up by using a cutoff EPSS of >8 may not be as important as the ejection fraction that is so low it can be seen on the ultrasound screen from across the room.
“E-point septal separation: a bedside tool for emergency physician assessment of left ventricular ejection fraction”