Echo for Right Ventricular Dysfunction in PE

RV Strain


Diagnostic Accuracy of Right Ventricular Dysfunction Markers in Normotensive Emergency Department Patients With Acute Pulmonary Embolism

Annals of Emergency Medicine September 2016 - Pubmed Link


Background

Patients diagnosed with pulmonary embolism (PE) range over a spectrum of severity from “possibly discharge” to “cardiac arrest”. Only 5% presents with signs of shock and are considered massive. Those without shock can still have considerable morbidity and mortality. Cardiac biomarkers such as brain natriuretic peptide (BNP) and troponin can be used as markers of right ventricular dysfunction. Transthoracic echocardiography is also used to evaluate for right ventricular (RV) dysfunction in the setting of PE. A combination of focused echocardiography by an emergency physician, serum cardiac biomarkers, and right ventricular assessment on computed tomography (CT) offers potential to be a readily available and accurate risk-stratification tool.


Questions

How accurate is goal-directed (AKA focused or point-of-care) echocardiography for RV dysfunction?

How accurate are serum cardiac biomarkers and CT for RV dysfunction?


Population

Prospective, consecutive ED patients over 1 year diagnosed with PE by CT angiography (CTA) or ventilation perfusion (V/Q) scan

Single center, academic urban hospital

Normotensive

Inclusion:

  • Age >18

  • CTA showing acute PE

  • V/Q read as high probability

  • Comprehensive echocardiography (by sonographer) could be performed within 24 hrs

Exclusion:

  • Criteria for massive PE (based on AHA definition) - SBP <90 x 15 min or requiring inotropic support and not attributed to other causes (arrhythmia, hypovolemia, sepsis, LV dysfunction, pulselessness, bradycardia)

  • Unable to tolerate echocardiogram

  • Images were “of inadequate quality”

  • The patient underwent intervention for PE (such as systemic or catheter-directed thombolysis, surgical embolectomy) between goal-directed echo and comprehensive echo


Who did the scans?

Usually one of 5 emergency physicians trained in “goal-directed echocardiography”

  • 1 was director of emergency US fellowship and registered diagnostic cardiac sonographer
  • 1 emergency ultrasound fellow
  • 3 emergency medicine residents

All had received training prior to study (at least 1 month of ultrasound rotation and >50 cardiac ultrasounds)

Study Training:

-2 hour lecture

-6 hours hands-on supervised by principal investigator

In 13 patients it was done by other resident or attending emergency physicians


Design

Prospective study of consecutive emergency department patients

Calculated test characteristics of emergency physician performed goal-directed echo


Intervention

Patient diagnosed with PE but not massive

Underwent goal-directed echo by study emergency physician (EP), interpreted by EP (blinded to CT and serum testing results)

Then underwent comprehensive echo by cardiac sonographer, interpreted by cardiologist (blinded to goal-directed exam)

If CT performed, LV;RV ratio assessed and if LV:RV ratio ≥1 → considered positive for RV dysfunction (used for calculation of CT test characteristics for RV dysfunction)


Also everyone got serum biomarkers drawn

Brain natriuretic peptide (BNP) >90 pg/mL = positive

Troponin I ≥0.07 ng/mL = positive


RV Dysfunction Severity Scale was Created

Part 1 - Goal-directed Echo

0 points = absence of RV enlargement

1 point = RV enlargement

2 points = RV enlargement + either RV systolic dysfunction or interventricular flattening

3 points = all three findings


Part 2 - Cardiac Biomarkers

0 points = absence of elevation in BNP and troponin

1 point = either BNP or troponin elevation

2 points = both elevated


Scan

Phased array transducer 1-5 MHz

Goal-Directed Echocardiography assessment of right ventricular dysfunction (as defined by this paper)

Assess for ANY of three findings - Needed at least 1 finding in at least 2 views

  1. Severe RV enlargement - RV:LV ratio ≥1 based on visual estimation during diastole. Also might note blunting or the normally narrow and sharp LV apex and enlarged basal RV diameter (>3.8cm)

  2. Severe RV systolic dysfunction - minimal to absent movement of RV free wall, Tricuspid annular planar systolic excursion (TAPSE) <1.0 cm (visually estimated, not necessarily measured), diminished inward movement of RV free wall (fractional change <18%)

  3. Interventricular septal flattening - loss of the normal rightward bowing, either with flattening of the septum or bowing toward left side

Recognize that these findings can all be present in chronic increased right sided pressures. Therefore these are not specific for pulmonary embolism

Learn how to do ultrasound for Right Heart Strain - 5 Minute Sono


Results

133 patients with PE over 1 year

Excluded:

4 with hypotension

3 with poor quality images

4 with chronic PE

1 refused to consent

6 did not receive comprehensive echo

N = 116

27 were positive for RV dysfunction on goal-directed echo

26 were positive on comprehensive echo


Primary Outcome

Goal-directed echo - test characteristics for diagnosing RV dysfunction (GDE score >0)

Sensitivity 100% (CI 87-100%)

Specificity 99% (CI 94-100%)

+LR 90.0

-LR 0

Single case of no RV dilation but other echo findings of RV dysfunction - agreement with comprehensive echo, not counted as RV dysfunction


Secondary Outcomes

Test Characteristics for Other Markers of RV Dysfunction

BNP elevation - Sens 88%, Spec 68%, +LR 2.8, -LR 0.17

Troponin I elevation - Sens 62%, Spec 93%, +LR 9.2, -LR 0.41

Cardiac biomarker score >0 - Sens 96%, Spec 66%, +LR 2.8, -LR 0.06

Central thrombus on CT - Sens 88%, Spec 60%, +LR 2.2, -LR 0.21

CT RV:LV ≥1 - Sens 91%, Spec 79%, +LR 4.3, -LR 0.11


Interobserver agreement of goal-directed echocardiography: kappa 0.69

67% of diagnosed PEs were outside of Monday to Friday 9am-5pm

Average time to comprehensive echo was 9.4 hours


Limitations

Single center

Well trained sonologists (42.2% performed by fellowship director who was RDCS or emergency ultrasound fellow)

Excluded those with inadequate quality images

Could have chronic RV dysfunction from causes

CT slices evaluating LV:RV ratio may not have been end diastole

Did not evaluate whether earlier diagnosis of RV dysfunction could have resulted in change in patient centered outcomes such as time to intervention, length of stay, etc.


Take Home Points

1. Goal-directed echocardiography can accurately diagnose RV dysfunction in the setting of PE with 100% sensitivity and 99% specificity in this study with experienced operators

2. Goal-directed echocardiography out performed cardiac biomarkers and CT findings in assessing for RV dysfunction in the setting of PE.


Our score

4 Probes


Cite this article as

Michael Prats, MD. Echo for Right Ventricular Dysfunction in PE. Ultrasound G.E.L. Podcast Blog. Published on December 05, 2016. Accessed on June 17, 2019. Available at http://www.ultrasoundgel.org/8.
Published on 12/05/16 01:00 AM
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