ekgs, stress tests and echos · an ekg is a recording of the electrical activity of the heart. •...

EKGs, Stress Tests and Echos

Valerie R. Kaufman, MD, DBIM, FACCVice President & Medical Director

September 2018

Michael Hill, FALU, FLMI, ARA, ACSDirector, Underwriting

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Underwriting Cardiac Disease

Template from www.presentationmagazine.com

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. . . Putting the Pieces Together

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Agenda

Review of cardiac anatomy and physiology

EKG overview

Stress test overview

NTproBNP interlude

Echocardiogram overview

Case studies

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Pre-Test! True or False?

1. The EKG is no longer a useful risk-assessment tool since echocardiograms and BNP are widely available.

2. An inadequate increase in heart rate (less than 85% predicted maximum) invalidates the findings on a regadenosine (Lexiscan) stress test.

3. NTproBNP is only elevated in heart failure.

4. The echocardiogram gives a real-time view of the motion of the myocardium and cardiac valves.

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Anatomy of the Heart

Author: Ties van Brussel Wikipedia Author: ZooFari Wikipedia

The heart is fixed within the body by the major vessels attached to it and by the fibrous skeleton provided by the heart valves and their supporting annuli. The ventricles and atria are free to enlarge and contract against the fixed plane.

http://upload.wikimedia.org/wikipedia/commons/e/e0/Heart_diagram-en.svghttp://upload.wikimedia.org/wikipedia/commons/e/e0/Heart_diagram-en.svghttp://commons.wikimedia.org/wiki/User:ZooFari

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The conduction system of the heart consists of specialized fibers that are adapted to the conduction of the electrical impulse at a much faster rate than that of muscle tissue. The SA node generates an impulse which spreads throughout the atria and on to the AV node. The AV node reconstitutes the impulse and delays transmission to the ventricles to allow the atria to finish contracting.

Conduction System of the Heart

Author : Madhero88 - Wikipedia

http://commons.wikimedia.org/wiki/User:Madhero88

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Cardiac Cycle

Author: Kalumet, selbst erstellt, 28.11.2005. - Wikipedia

Electrical• SA node fires• Impulse spreads throughout atria and to AV node• AV node reconstitutes/slows• Impulse enters Bundle of His, bundle branches, Purkinje

fibers

• Conduction system repolarizes

Mechanical• Atria contract (systole)• Pressure increases in ventricles, closing mitral and tricuspid

valves; atria relax (diastole)

• Ventricles contract (systole); aortic and pulmonic valves open• Ventricles relax (diastole), aortic and pulmonic valves close• Mitral and tricuspid valves open and ventricles fill passively • Atrial “kick” contributes 10-15% of cardiac output

http://commons.wikimedia.org/wiki/User:Kalumet

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The Hard-Working Heart

The myocardium is constantly working• Pumps about 5 liters of blood/minute• About 100,000 heartbeats/day• Pumps about 2,600 gallons of blood/day

The coronary arteries must provide adequate oxygen and nourishment

Cardiac reserve• Cardiac output may be increased to as much as 35 liters/minute • Normal coronary arteries can increase myocardial blood supply 5-6 fold if needed• Early stages of disease of the heart often associated with reduced cardiac reserve• Cardiac reserve diminishes with aging• Atrial fibrillation reduces cardiac output by 10-15%

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Categories of Cardiac Disease

Coronary artery disease

Valvular heart disease

Cardiomyopathy

Congenital heart disease

Hypertensive heart disease

Primary arrhythmias

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The ElectrocardiogramEKG, ECG

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Electrocardiogram (EKG, ECG) An EKG is a recording of the electrical activity of the heart.

• 12 different leads “look” at this activity from different perspectives• Voltage is graphed against time• Voltage polarity (negative or positive) indicates direction of the flow of the electrical impulse

The EKG’s primary purpose is to determine the heart rate and rhythm• Rate: how fast the heart is beating• Rhythm: determines the origin of the pacing impulse and the integrity of the conduction system

The EKG can give indirect information about other conditions• Ischemia • Infarction or other scarring• Hypertrophy• Electrolyte imbalance, drug effects• Pericarditis• Heart position in the chest (COPD, dextrocardia, chest wall deformities)

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EKG Waves and Complexes

Created by Agateller (Anthony Atkielski), converted to svg by atom. - Wikipedia

The P wave corresponds with atrial activation. The PR interval is the time from the activation of the atria to the activation of the ventricles. It indicates the time it takes the impulse generated in the SA node to travel through the atria, into and out of the AV node.

This is followed by the QRS complex (Q, R and S waves), which corresponds to the activation of the ventricle.

The ST segment and T wave correspond with ventricular repolarization.

The QT interval is the time it takes for ventricular activation and repolarization.

http://en.wikipedia.org/wiki/User:Agatellerhttp://cs.wikipedia.org/wiki/Wikipedista:atom

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EKGs Were First Developed in 1903

Einthoven’s EKG rig. 1903 (3 leads), public domain - Wikipedia

EKGs were first developed by Willem Einthoven in Holland. Einthoven used a light projected on a moving mirror and reflected on a fluorescent plane to visualize the EKG.

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The standard positioning of the EKG leads is not random. The leads are arranged in a standard way designed to provide adequate and consistent EKG readings. This consistency is required for pattern recognition and interpretation of the EKGs.

The EKG Waves

P wave, atrial contraction starts

QRS complex, ventricular contraction

T wave, ventricular contraction ends

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Underwriting EKG Findings

Considerations• EKG findings provide direct information about the electrical activity of the heart only • Normal variants must be differentiated from potentially abnormal findings• EKG findings should be interpreted in context of other available information

The Questions • Is it a new finding?• Any other findings on the EKG?• Is there a known history of cardiac disease, and has there been any cardiac evaluation?• What other medical history is there?• What are the potential causes?• What are the potential complications?

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Case Study: Right Bundle Branch Block (RBBB)

62-year-old man, nonsmoker, 6’2, 212 lbs (BMI 27.2)

Sent to reinsurance due to EKG• Known to have a RBBB for at least 7 years (found on screening EKG)• No cardiac symptoms or history• No significant medical history

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Rabbit Ears

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Underwriting EKGs: The Questions

Is it a new finding?

Any other findings on the EKG?

Is there a known history of cardiac disease, and has there been any cardiac evaluation?

What other medical history is there?

What are the potential causes?

What are the potential complications?

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Causes of RBBB

Conduction system disease

CAD, especially involving right coronary artery

Right ventricular hypertrophy

Pulmonary embolism

Congenital heart disease (especially Tetralogy of Fallot, ASD)

Myocarditis/Cardiomyopathy

HTN

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Underwriting EKGs: The Questions

Is it a new finding?

Any other findings on the EKG?

Is there a known history of cardiac disease, and has there been any cardiac evaluation?

What other medical history is there?

What are the potential causes?

What are the potential complications?

No, present x 7 years

No

Nothing significant

No history of cardiac disease, no evaluation

Conduction system disease

Progressive conduction system disease, underlying heart disease

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Stress Tests

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Stress Testing

Purpose: To assess ability of coronary arteries to increase flow compared to rest/baseline. Can be used to screen for or to follow known CAD.

Stress (increases demand or causes flow differential)• Exercise by treadmill or bicycle - increases heart rate, BP and contractile state• Dobutamine – works much like exercise to increase heart rate, BP and contractile state• Vasodilators – adenosine, regadenosine (Lexiscan), dipyridamole

Monitoring for results• EKG• Echo• Nuclear (MPI)

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Vasodilator Stress Tests

Includes adenosine/regadenosine and dipyridamole

Mechanism • Dilate coronary arteries• Flow increases more in normal vessels than in diseased vessels• Relative differences in perfusion show up on imaging• Rarely induce actual ischemia• Often combined with low level walking as this may reduce side effects

How differs from exercise stress test• Heart rate and BP not expected to increase significantly• EKG not expected to show ischemic changes• Symptoms more likely to be side effect of drug than due to ischemia

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Stress Testing as a Screen for CAD

Accuracy of any screening test depends on • Prevalence of disease • Sensitivity and specificity of test

Sensitivity = True positive rate

Specificity = True negative rate

Exercise EKG: Sensitivity and specificity in the range of 60 – 75%

Imaging studies: Sensitivity and specificity in the range of 80 – 90%

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Stress Testing in Known CAD

Indicated to assess significance of new symptoms

Could be considered • Evaluation of incomplete revascularization• Assessment of the adequacy of medical therapy• Need to evaluate coronary status in anticipation of major noncardiovascular surgery

Should not expect “routine” follow up stress testing in stable CAD

Fihn SD, Gardin JM et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force, American Association of Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol 2012;60:e44-164.

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The Exercise EKG – More Than ST Segments!

Exercise capacity: duration and amount of exertion

BP response

Symptoms

ST segment changes

Arrhythmias

Heart rate recovery

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Interpreting Stress Tests

Type of Test Component Criteria for Positive Test Other Adverse Findings

Exercise or Dobutamine

EKG • ST depression• Anginal pain

• ↓ Exercise capacity• Abnormal BP response• Arrhythmias

Nuclear imaging

• Reversible perfusion defect• Transient regional wall motion

abnormality

• LV dilatation• Fixed perfusion defect• Failure to increase EF

Echo imaging • Transient regional wall motion abnormality

• Failure to increase EF

• LV dilatation• Fixed wall motion abnormality• Valvular dysfunction

Vasodilator(regadenosine, dipyridamole)

• Positive imaging findings• Do NOT expect EKG changes

• Symptoms such as CP, SOB –often side effect from drug rather than due to ischemia

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Not All ST Depression is CAD . . .

Causes of ST depression on exercise EKG• CAD• Hypertensive blood pressure response• LVH• Cardiomyopathy• Bundle branch block• Other depolarization abnormalities, like pre-excitation (such as WPW)• Electrolyte imbalance

NTproBNP

Wikimedia Commons, CC 3.0. Author OpenStax College. Anatomy & Physiology, Connexions Website. http://cnx.org/content/col11496/1.6/

http://cnx.org/content/col11496/1.6/

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Natriuretic Peptides Family of peptides

• ANP: Atrial natriuretic peptide (1983)• BNP: Brain (or B-type) natriuretic peptide (1988)• CNP: C-type or vascular natriuretic peptide (1990)• DNP: D-type natriuretic peptide (early 1990s)

Effects• Natriuretic• Diuretic• Vasodilator• Antiproliferative

Play role in • Regulation of blood pressure• Regulation of plasma volume• Attenuation of cardiac hypertrophy

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B-Type (Brain) Natriuretic Peptides Made by myocardial cells

Stored as a prohormone: proBNP

When released, is cleaved into 2 fragments• BNP – biologically active, short half-life• NTproBNP – not biologically active, but long half-life and stable at room temperature

Normally present in small quantities in the blood

Released in increased amounts in response to wall stress (pressure, stretch)

May be used clinically to follow status of known cardiac disease

Correlates with cardiovascular and all-cause mortality

Brain image: Pixabay, free for commercial use, no attribution required

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ProBNP, BNP and NTproBNP

NTproBNP

ProBNP

BNP

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NTproBNP May Be Elevated In

Heart failure

CAD

Cardiomyopathy

Valvular heart disease

Congenital heart disease

Secondary LVH

Atrial fibrillation

Advancing age

Anemia

Renal failure

Pulmonary HTN

Bacterial sepsis

Severe burns

Toxic insults such as chemotherapy or envenomation

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Clinical Utilization of BNP/NTproBNP

To help determine if acute SOB is due to a cardiac or noncardiac cause

To help confirm diagnosis of heart failure

To follow status and response to treatment

To assess risk for development of clinical heart failure

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NTproBNP and Mortality

Predicts cardiovascular and all-cause mortality

Predicts mortality independent of • Traditional cardiac risk factors• Ejection fraction

Studied clinically in healthy community-dwelling populations in the U.S. and in Europe

Single measurement is predictive, serial measurements add value

Stable at room temperature and does not require special handling

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The Appeal of NTproBNP in Insurance Screening

May be ↑ in many types of cardiac disease • Before heart failure develops• Even before clinical onset of cardiac disease

o As much as 75% systolic dysfunction in the community is undetectedo Diastolic dysfunction even less likely to be detectedo About 500,000 people in the U.S. have HCM and most are unawareo Most heart diseases are asymptomatic in early stages

Predicts all cause mortality, even after adjusting for traditional risk factors

Obtained by simple blood draw; stable in transit

Cost is acceptable

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Utilization of NTproBNP in Insurance Insurance labs have been offering for >10 years

In place of stress tests

As additional age-and-amount testing requirement

In place of ECGs

To support automated underwriting systems

Challenge: how to interpret NTproBNP values and assign mortality risk

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Mortality Ratio for All-Cause Mortality

0

100

200

300

400

500

600

700

800

1000

Male age 50-69 Male age 70-89 Female age 50-69 Female age 70-89

Fulks M, Kaufman V et al. NT-proBNP predicts all-cause mortality in a population of insurance applicants, follow-up analysis and further observations. J Insur Med 2017;47:4

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Clinical Reference Laboratory Study 2017

NTproBNP(in pg/ml)

≤ 75 (ref) 76-175 176-300 301-500 501-1000 > 1000

MenAge 50-69

1 1.85 2.54 6.55 6.63 16.15

MenAge 70-89

1 1.72 2.84 3.23 5.07 7.17

WomenAge 50-69

1 0.88 1.58 2.65 4.11 8.24

WomenAge 70-89

1 1.49 1.96 2.29 4.14 7.7

Relative Risk for All-Cause Mortality by NTproBNP Level


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Clinical Reference Laboratory Study 2017

Age ≤ 75 ≤ 175 ≤ 300 ≤ 500 ≤ 1000

MEN

50-59 90.8% 98.5% 99.4% 99.8% 99.9%

60-69 76.2% 94.3% 97.6% 98.8% 99.6%

70-79 52.2% 82.4% 91.8% 95.9% 98.5%

WOMEN

50-59 74.4% 96.6% 99.3% 99.8% 100%

60-69 57.5% 89.1% 97.0% 99.0% 99.7%

70-79 34.8% 72.6% 88.7% 95.5% 98.7%


Cumulative Distribution of NTproBNP (pg/ml) Values by Age and Sex*

*For applicants denying heart disease

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NTproBNP and ECGs

Different screening tools that detect different risks

Potential advantages of NTproBNP over ECGs• Cheaper• May be added to regular insurance blood profile• Fewer quality issues• Does not require interpretation by specially trained staff• May better facilitate automation

Caveats• Not “equivalent” to the ECG• Requires development of new guidelines• Mortality slippage can occur if cutpoints and guidelines not aligned to expectations

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The Echocardiogram

Author: Kjetil Lenes Wikipedia

http://commons.wikimedia.org/wiki/User:Ekko

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Echocardiogram Also known as cardiac ultrasound

Noninvasive

No radiation

Readily available

Provides real time images of the heart

Cost is a consideration

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Traditional Echo Modalities

M mode – 1 dimensional “icepick” view through various planes of the heart • Measure chamber sizes and ventricular wall thickness

2D – 2 dimensional, real-time motion• Measure chamber sizes and ventricular wall thickness

Doppler – assesses characteristics of blood flow• Assess valve function• Assess pressures• Assess for abnormal flow

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Enhancements to Echocardiography

Addition of color

Echo contrast (microbubbles)

Transesophageal approach

Tissue Doppler

3D imaging

Speckle and strain imaging

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M Mode Echo

The computer imaging system calculates sizes and displays them automatically in M mode. The left ventricle is being measured in this example. Also note the timing EKG tracing.


The small figure in the circle is the 2D echo


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2D Views

These are some of the echocardiographic views available through different transducer positioning. Each view shows only a narrow plane of tissue through the heart. Some of these views can be difficult to obtain depending on the size and shape of the patient’s chest. Some structures can be only be seen in specific views.

Authors: Patrick J. Lynch and C. Carl Jaffe Wikipedia

http://upload.wikimedia.org/wikipedia/commons/4/46/LeftVentricleShortAxis.gifhttp://upload.wikimedia.org/wikipedia/commons/4/46/LeftVentricleShortAxis.gifhttp://upload.wikimedia.org/wikipedia/commons/7/7a/Apical_4_chamber_view.gifhttp://upload.wikimedia.org/wikipedia/commons/7/7a/Apical_4_chamber_view.gifhttp://upload.wikimedia.org/wikipedia/commons/1/16/LeftParasternalLongAxis.gifhttp://upload.wikimedia.org/wikipedia/commons/1/16/LeftParasternalLongAxis.gif

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Doppler Echocardiogram• Doppler of a ventricular septal

defect showing the abnormal flow of blood across the defect in the septum.

• The EKG tracing indicates (red mark) the point of the cycle where this picture was taken.

• Very small defects with little flow may require microbubble contrast enhancement.


Doppler evaluation of the speed of flow across a valve or septal defect can be used to calculate the size of the valve opening or defect. Higher rates of flow indicate tighter openings and vice versa.


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Echocardiogram 2D and 3D – in motion

Above: Sketch labeling the 3D picture. Mitral and aortic valves on right of image, tricuspid valve left.



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Information Provided by the Echo

Cardiac chamber sizes and wall thickness

Appearance of the heart valves

Assessment of valvular function and dysfunction

Assessment of systolic and diastolic function of the myocardium

Assessment of presence, direction and speed of blood flow

Estimation of pressures within cardiac chambers

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Limitations of the Echocardiogram

Body habitus• Chest wall deformities such as pectus excavatum and

kyphoscoliosis distort anatomy• Obesity makes it difficult for sound waves to penetrate• Sound waves don’t travel well in air – hyperinflated lungs make it

difficult to acquire clear images (COPD, asthma, ventilator patients)

Be careful when “technically difficult” study

Skill and patience of the examiner and methodology of interpreter

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Normal ValuesStructure Reference Range

LVIDdLVEDD

Left ventricular internal dimension in diastoleLeft ventricular end diastolic dimension

3.9 – 5.3 cm (women)4.2 – 5.9 cm (men)

LVIDsLVESD

Left ventricular internal dimension in systoleLeft ventricular end systolic dimension

IVSd Interventricular septum in diastole 0.6 – 0.9 cm (women)0.6 – 1.0 cm (men)IVSs Interventricular septum in systole

LVPWd Left ventricular posterior wall in diastole 0.6 – 0.9 cm (women)0.6 – 1.0 cm (men)LVPWs Left ventricular posterior wall in systole

LA Left atrium 2.7 – 3.8 cm (women)3.0 – 4.0 cm (men)Lang RM, Bierig M et al. Recommendations for Chamber Quantification: a report from the American Society of Echocardiography’s Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005;18;1440-1463.

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Value of the Echo in Different Types of Heart Disease

Type of Disease How an Echo Can Help

Coronary Artery Disease • Regional wall motion abnormalities

Valvular Heart Disease• Valve structure• Degree of dysfunction (stenosis, regurgitation)• Compensatory changes (dilatation, hypertrophy)

Cardiomyopathy • Type and severity

Congenital Heart Disease • Type and severity• Compensatory changes (dilatation, hypertrophy)

Hypertensive Heart Disease • Compensatory changes

Primary Arrhythmias • Excludes structural abnormalities

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Review of Pretest

1. The EKG is no longer a useful risk assessment tool since echocardiograms and BNP are widely available.

2. An inadequate increase in the heart rate (less than 85% predicted maximum) invalidates the findings on a regadenosine (Lexiscan) stress test.

3. NTproBNP is only elevated in heart failure.

4. The echocardiogram gives a real time view of the motion of the myocardium and cardiac valves.

FALSE

TRUE

FALSE

FALSE

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Putting the Pieces Together

Consider all the different types of cardiac disease, not just CAD

Consider all the pieces of evidence available

Recognize the limitations of the various tests

Give more weight to more predictive tests

Go with the “preponderance of the evidence”

Stay focused on assessing risk rather than making a diagnosis

©2018 RGA. All rights reserved.

EKGs, Stress Tests and EchosUnderwriting Cardiac Disease. . . Putting the Pieces TogetherAgendaPre-Test! True or False? Slide Number 6Conduction System of the HeartCardiac CycleThe Hard-Working HeartCategories of Cardiac DiseaseThe Electrocardiogram��EKG, ECGElectrocardiogram (EKG, ECG)EKG Waves and ComplexesEKGs Were First Developed in 1903The EKG WavesUnderwriting EKG FindingsCase Study: Right Bundle Branch Block (RBBB)Rabbit EarsUnderwriting EKGs: The QuestionsCauses of RBBBUnderwriting EKGs: The QuestionsStress TestsStress TestingVasodilator Stress TestsStress Testing as a Screen for CADStress Testing in Known CADThe Exercise EKG – More Than ST Segments! Interpreting Stress TestsNot All ST Depression is CAD . . . NTproBNPNatriuretic PeptidesB-Type (Brain) Natriuretic PeptidesProBNP, BNP and NTproBNPNTproBNP May Be Elevated InClinical Utilization of BNP/NTproBNPNTproBNP and MortalityThe Appeal of NTproBNP in Insurance Screening Utilization of NTproBNP in InsuranceMortality Ratio for All-Cause MortalityClinical Reference Laboratory Study 2017Clinical Reference Laboratory Study 2017NTproBNP and ECGsThe EchocardiogramEchocardiogramTraditional Echo Modalities Enhancements to EchocardiographySlide Number 47Slide Number 48Slide Number 49Slide Number 50Information Provided by the EchoLimitations of the EchocardiogramNormal ValuesValue of the Echo in Different Types of Heart DiseaseReview of Pretest Putting the Pieces TogetherSlide Number 57Slide Number 58

ekgs, stress tests and echos · an ekg is a recording of the electrical activity of the heart. •...

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