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Use of Cardiac POCUS in Diagnosis of HFrEF in a Patient with Ischemic Stroke

By Currents Editor posted 08-16-2022 10:21

  

Donald Langan, MD, PharmD, Alexandra Schroeder, PA-C

Ischemic strokes in younger adults, those 18 to 50 years old, account for approximately 10% to 15% of all ischemic strokes. Risk factors for stroke between younger and older patients tend to be similar. Younger patients suffer from cardioembolic or embolic strokes of undetermined significance, while older adults, greater than 50 years, tend to have a higher frequency of ischemic stroke due to large vessel atherosclerosis or lacunar infarction.1 Risk factors for cardioembolic stroke include atrial fibrillation, acute myocardial infarction, and patent foramen ovale.2 Atrial fibrillation can lead to tachycardia induced cardiomyopathy, which if left untreated may progress to acute decompensated heart failure.3 Point of Care Ultrasound (POCUS) can be a useful diagnostic tool in assessing and estimating cardiac function in real time.4,5,6,7 There are both qualitative and quantitative assessments that can be made when evaluating for reduced ejection fraction with POCUS. The qualitative hallmark findings include decreased left ventricular excursion during systole and reduced migration of the anterior mitral valve leaflet during diastole. The distance between the anterior mitral valve leaflet during diastole and the interventricular septum, known as the E-Point Septal Separation, can be used to estimate ejection fraction (EF).6 

A 35-year-old male with a history of obesity presented with dizziness, slurred speech, and recent fall. In the Emergency Department the patient was noted to be in atrial fibrillation with rapid ventricular response (RVR) and required intravenous diltiazem for heart rate control prior to neuroimaging. Thrombolysis was deferred as the patient had a rapidly improving exam and National Institute of Health Stroke Scale (NIHSS) of 0. Computed Tomography Angiography exam revealed non-calcified intraluminal thrombus in left middle cerebral artery segment two (M2) thrombus. Thrombectomy was deferred due to rapidly improving neurologic exam and NIHSS 0. Magnetic Resonance Imaging ultimately was revealing for an area of diffusion restriction with apparent diffusion coefficient mismatch, consistent with acute ischemic stroke in the left posterior insula.  

The patient was admitted to the neurocritical care unit for close neuro-monitoring. His course was complicated by persistent atrial fibrillation with RVR and new heart failure with reduced ejection fraction  (HFrEF). Reduced EF was first noted on the POCUS and later confirmed on formal transthoracic echocardiogram (TTE), with an EF of 8%. The patient did not otherwise have overt signs of vascular congestion on clinical exam. Chest radiograph revealed enlarged cardiac silhouette, but without significant pulmonary edema. B-type natriuretic peptide was elevated to 363pg/ml.  

On hospital day two the heart failure service was consulted and the patient was subsequently transferred to the cardiac critical care unit (CCU). In the CCU, the patient was diuresed with intravenous furosemide, loaded with digoxin, and started on a heparin drip. He underwent a cardiac catheterization that was negative for atherosclerotic coronary artery disease. Two days later he underwent transesophageal echocardiography with direct current cardioversion and was converted to normal sinus rhythm. For his HFrEF he was initiated on guideline directed medical therapy including: metoprolol, dapagliflozin, sacubitril/valsartan, and eplerenone. The patient was subsequently loaded with amiodarone for rhythm control. The patient was discharged home with a life vest and close cardiac follow-up.  During follow up with cardiology patient’s EF was noted to have recovered to about 35%. He has had recurrence of his atrial fibrillation despite cardiac ablation and is taking apixaban for secondary stroke prevention.  

Additional patient social history revealed excessive alcohol intake (3-4 drinks a week day and 7-10 drinks on weekends), in addition to workout supplements that included 600mg of caffeine per day. Both moderate to heavy alcohol consumption and caffine intake have been associated with new onset atrial fibrillation.8,9 

In this image (image 1), you can see the parasternal short axis view that is a great view for qualitatively and quickly assessing the ejection fraction (EF).  This view shows you both the right and left ventricles at work. In this case, symmetrically poor ventricular wall thickening demonstrates a severely reduced EF.  

For this patient the parasternal long axis was also utilized which demonstrated poor septal wall movement, severe dilation of LV (image 2).  Notice the decreased anterior mitral leaflet excursion compared to the interventricular septum during diastolic filling. The relationship between the excursion of the anterior mitral leaflet during diastole, known as the E-Point, and it’s relative distance to the septum, measured in millimeters (mm), is referred to as the E-Point to Septal Separation (EPSS). The greater the distance between these two points, the more reduced the ejection fraction is thought to be. 6 In 2006, Silverstein and colleagues reviewed cardiac MRI data from their institution and utilized EPSS and linear regression models, comparing EPSS to the accepted most accurate form of estimation of EF, Simpson’s method. They proposed the following calculation for using EPSS to estimate EF:10 

LVEF = 75.5 – (2.5 x EPSS) 

A subsequent educational study, designed for having practitioners quickly interpret normal from abnormal EF, proposed using 8mm as a simple cutoff for determining ‘normal’ EPSS. Where an EPSS <8mm means presumed normal EF and EPSS  >8mm means reduced EF. The greater the distance, the worse the implied ejection fraction.11 

EPSS > 8mm = reduced EF

A 2012 retrospective single center study evaluated patients who had undergone a cardiac MRI and applied a EPSS to calculate EF and then this to Simpson Model for calculating EF, accepted to be the most accurate model for calculating EF in cardiac MRI, similar to Silverstein. In this study they further quantified EPSS.12 

EPSS (mm)

LVEF

≤7.3

Normal (≥60%)

7.4-8.9

Low normal (55-59%)

9-13.9

Mild systolic dysfunction (40-54%)

14-17.1

Moderate systolic dysfunction (30-39%)

>17.1

Severe systolic dysfunction (<30%)

  Table adapted from Elagha 2012 

Cardiac POCUS is a fast, convenient, and safe bedside diagnostic tool that allows practitioners access and obtain crucial clinical information in real-time. The qualitative method for assessing EF, simply looking at the cardiac muscles and how well they squeeze, allows for the practitioner to glean real time information that can help guide the treatment and workup of the patient. Simple measurements like the EPSS can even allow the clinician to calculate rough estimates of how severely reduced a patient's EF may be. Limitations to using EPSS include prosthetic mitral valves, aortic insufficiency, mitral insufficiency, and mitral stenosis. This case illustrates the utility of bedside cardiac POCUS in identifying and diagnosing HFrEF in a young patient with an embolic stroke due to new onset atrial fibrillation. 

References

  1. George, MG. Risk Factors of Ischemic Stroke in Younger Adults. Stroke. Volume 51, Issue 3, March 2020; Pages 729-735 https://doi.org/10.1161/STROKEAHA.119.024156
  2. Boehme AK, Esenwa C, Elkind MSV. Stroke Risk Factors, Genetics, and Prevention. Circulation Research. Volume 120, Issue 3, 3 February 2017; Pages 472-495 https://doi.org/10.1161/CIRCRESAHA.116.308398 
  3. Huizar JF, Ellenbogen KA, Tan AY, Kaszala K. Arrhythmia-Induced Cardiomyopathy: JACC State-of-the-Art Review. J Am Coll Cardiol 2019;73:2328-2344
  4. Melgarejo, S. Schaub A, Noble VE. Point of Care Ultrasound: An Overview. ACC.org 31 October 2017. https://www.acc.org/latest-in-cardiology/articles/2017/10/31/09/57/point-of-care-ultrasound 
  5. Foley TA, Mankad SV, Anavakar NS, et al. Measuring Left Ventricular Ejection Fraction - Techniques and Potential Pitfalls. European Cardiology 2012;8(2):108-14 DOI:https://doi.org/10.15420/ecr.2012.8.2.108
  6. Dinh V, Beaven A, Bashir R. Assessing Left Ventricular Ejection Fraction With Echocardiography. POCUS 101 https://www.pocus101.com/assessing-left-ventricular-ejection-fraction-with-echocardiography/#Parasternal_Long-Axis_PSLA_View 
  7. Sievers B, Kirchberg S, Franken U, Puthenveettil BJ, Bakan A, Trappe HJ. Visual estimation versus quantitative assessment of left ventricular ejection fraction: a comparison by cardiovascular magnetic resonance imaging. Am Heart J. 2005 Oct;150(4):737-42. doi: 10.1016/j.ahj.2004.11.017. PMID: 16209976.
  8. Samokhvalov AV, Irving HM, Rehm J. Alcohol consumption as a risk factor for atrial fibrillation: a systematic review and meta-analysis. Eur J Cardiovasc Prev Rehabil. 2010;17(6):706-712. doi:10.1097/HJR.0b013e32833a1947
  9. Thyagarajan B, Alagusundaramoorthy SS, Agrawal A. Atrial Fibrillation Due to Over The Counter Stimulant Drugs in A Young Adult. J Clin Diagn Res. 2015;9(8):OD05-OD7. doi:10.7860/JCDR/2015/13483.6330                  
  10. Jay R. Silverstein, Nicholas H. Laffely, Robert D. Rifkin,Quantitative Estimation of Left Ventricular Ejection Fraction from Mitral Valve E-Point to Septal Separation and Comparison to Magnetic Resonance Imaging,The American Journal of Cardiology,Volume 97, Issue 1,2006,Pages 137-140,ISSN 0002-9149,https://doi.org/10.1016/j.amjcard.2005.07.118.
  11. Jacob M, Shokoohi H, Moideen F, Pousson A, Boniface K. An Echocardiography Training Program for Improving the Left Ventricular Function Interpretation in Emergency Department; a Brief Report. Emerg (Tehran). 2017;5(1):e70.
  12. Elagha, A. & Fuisz, A. Mitral valve E-Point to Septal Separation (EPSS) measurement by cardiac magnetic resonance Imaging as a quantitative surrogate of Left Ventricular Ejection Fraction (LVEF). J Cardiov Magn Reson, P154 (2012).

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