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Cardiac Diagnostics Made Simple

Lori Savard, RN, BSc, BN, NP May 3, 2014 MAZ Cardiology Update. Cardiac Diagnostics Made Simple. Disclosure of Commercial Support. Received financial support from AstraZeneca in the form of honorarium for participation on Advisory Board. Potential for conflict(s) of interest : none.

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Cardiac Diagnostics Made Simple

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  1. Lori Savard, RN, BSc, BN, NP May 3, 2014 MAZ Cardiology Update Cardiac DiagnosticsMade Simple

  2. Disclosure of Commercial Support Received financial support from AstraZenecain the form of honorarium for participation on Advisory Board. Potential for conflict(s) of interest: none

  3. Increase understanding regarding cardiac diagnostics What are underlying principles of operation? What information does a specific test provide? What is the appropriate patient population? Review concepts of pretest probability, sensitivity and specificity Apply principles to clinical scenarios. Objectives

  4. Symptoms: Mid-sternal pressure with some radiation right arm Intermittently related to exertion Often resolves with rest but not always “continues on and works through it” CRF: HTN Dyslipidemia Impaired FG Quit smoking 6 months ago Case 1 55 female with 6 month history of CP PMHx: depression, fibromyalgia ECG: LBBB at 68 bpm. B/P: 132/74 BMI: 31

  5. Which Test to Choose? None Stress MRI PET CT MIBI Coronary CT Exercise Stress Test Dobutamine Stress Echo Coronary Calcium Score

  6. Level of Diagnostics Coronary Angiogram Second Level Nuclear Echo MRI More invasive Less accessible Entry Level Treadmill Coronary Calcium CT Angio

  7. Pretest Probability of CAD Type of Chest Pain Gender Age

  8. Types of Chest Pain

  9. Pretest Probability of CAD

  10. Pretest Probability of CAD

  11. What information does this test provide? Ischemia Functional capacity Arrhythmia Accessible Relatively inexpensive Safe In right patients: serious complications Death or MI is 0.01% (1/10000) Rate of VT/VF is about 1/5000 Exercise Stress Test texasheartinstitute.org www.acc.org/clinical/guidelines/exercise

  12. EST recommended as initial choice if: Can exercise No absolute contraindications Caution with relative contraindications Consider resting ECG abnormalities Best if intermediate risk of CAD Is this an appropriate initial test for this patient? ACC/AHA Guidelines for Exercise Testing: Executive Summary

  13. Absolute and Relative Contraindications Absolute • Acute phase ACS • Acute myo/pericarditis • Rapid arrhythmias • Symptomatic severe AS • Severe anemia • Acute illness/infx • Hyperthyroidism • Acute aortic dissection Relative • HCM • Left main stenosis • Severe HTN (>200/110) • HF • Electrolyte abnormalities • Tachy/brady arrhythmias • Mental or physical limitations www.acc.org/clinical/guidelines/exercise

  14. Absolute and Relative Contraindications Absolute • Acute phase ACS • Acute myo/pericarditis • Rapid arrhythmias • Symptomatic severe AS • Severe anemia • Acute illness/infx • Hyperthyroidism • Acute aortic dissection Relative • HCM • Left main stenosis • Severe HTN (>200/110) • HF • Electrolyte abnormalities • Tachy/brady arrhythmias • Mental or physical limitations ACUTE ILLNESS

  15. ST- segment changes Depression or elevation Ventricular strain patterns RVH LVH T-wave changes Inversions Conduction abnormalities LBBB RBBB Prolonged QT interval Resting ECG Abnormalities www.acc.org/clinical/guidelines/exercise

  16. Sensitivity: probability a test says someone has disease which is true. Disease correctly identified. (TRUE) Specificity: probability a test says someone doesn’t have disease which is true. How good is the EST? NCSSM Statistics Leadership Institute July 1999

  17. Sensitivity: 65 - 78%. Mean 68% 68% Positives correctly identified . Specificity: 70 - 80% Mean 77% 77% Negatives correctly identified. If Low CAD Probability : High false positive If High CAD probability: High false negative Women More catecholamines: more vasoconstriction: more false positives Low false negative rate suggesting good rule out CAD with negative EST Hill, J. BMJ Volume 324. 4 May 2002 Taylor et al. Can Jour Card 29 (2013) 285-296 Tak, T. Post Med Online (115) June 2004 No 6

  18. Accessible and relatively inexpensive Provides important prognostic information Duke Treadmill Score (based on minutes Bruce Protocol, ST deviation, angina) Why Bother Exercise Stress Testing? Adapted from Mark et al. Ann Inter Med 1987;106:793

  19. What makes a ‘Positive EST’? (Bruce Protocol) • Target HR met (220 – pt’s age) x 85% If not: non-diagnostic • ST Changes: • At least 1 mm ST depression (horizontal or down sloping) in two contiguous leads Other factors: functional capacity, total time, symptoms, arrhythmias. Bad signs: • Drop in BP despite workload • ST elevation • Early + within 6 min • Persistent ST depression in recovery • ST depression in 5 or more leads Hill, J. BMJ Volume 324 4 May 2002

  20. Symptoms: Mid-sternal pressure with some radiation right arm Intermittently related to exertion Often resolves with rest but not always “continues on and works through it” CRF: HTN Dyslipidemia Impaired FG Quit smoking 6 months ago Case 1 – EST? 55 female with 6 month history of CP PMHx: depression, fibromyalgia ECG: LBBB at 68 bpm. B/P: 132/74 BMI: 31

  21. Pretest Probability of CAD

  22. Symptoms: Mid-sternal pressure with some radiation right arm Intermittently related to exertion Often resolves with rest but not always “continues on and works through it” CRF: HTN Dyslipidemia Impaired FG Quit smoking 6 months ago Case 1 55 female with 6 month history of CP PMHx: depression, fibromyalgia ECG: LBBB at 68 bpm. B/P: 132/74 BMI: 31

  23. Other Tests to Consider? Stress MRI MIBI PET CT Perfusion Scan Exercise Stress Test Dobutamine Stress Echo Coronary Calcium Score

  24. Calcium deposits found in plaques Increasing amounts with age Relationship exists between amount of calcium plaques and coronary events Coronary Calcium Scoring (CAC) http://www.nhlbi.nih.gov/health/health-topics/images/ct_calcium.jpg

  25. Anatomical assessment Coronary lumen itself is not visualized Positive is any calcium found in coronary arteries. Can measure density and extent of calcifications in coronary wall: “Agatston score” Coronary Calcium Scoring http://www.nhlbi.nih.gov/health/health-topics/images/ct_calcium.jpg

  26. http://www.dekkers.us/images/chart.jpg

  27. Positives Positive test close to 100% accurate for presence of plaque. High sensitivity (disease correctly identified) High negative predictive value. If CAC scores over 100: treat risk factors more aggressively as predictive of future coronary events Negatives Can predict risk but cannot diagnose obstructive disease Difficulty identifying soft plaque or unstable plaque. May require beta blocker to slow heart for enhanced imaging Radiation: 1-3 mSv (5-8 sec) (One CXR= 0.1 mSV) (Background radiation 1 year = 1.8 to 3 mSv) US: cost: $350 to patient Krause,R. (2011). Review of cardiac tests [Electronic version]. Retrieved Oct 17, 2011 from http://emedicine.medscape.com/article/811577-overview#a1 Coronary Calcium Score

  28. Detailed information coronary anatomy and aneurysms Identifies presence of atherosclerotic disease Radiation exposure significant although ↓ Requires iodinated contrast (kidneys) Requires beta blockade prior for better image quality Operator expertise Coronary CT Angiography Krause,R. (2011). Review of cardiac tests [Electronic version]. Retrieved Oct 17, 2011 from http://emedicine.medscape.com/article/811577-overview#a1

  29. Positive Cardiac and non-cardiac structural visualization Non-invasive High negative predictive value Diagnosis and risk assessment of low to intermediate risk CAD Technological advancements: less radiation and enhanced imaging Ajlan,A.,Heilbron, B.,& Leipsic, J. (2013). Coronary computed tomography angiography for stable angina: past, present and future. Canadian Journal of Cardiology, 29, 266-274. Bluemke, D., Achenbach, S., Budoff, M et al. (2008).Noninvasive coronary artery imaging – Scientific Statement. [Electronic version]. Retrieved June 16, 2009 from http://circ.ahajournals.org. ACCF/SCCT/ACR/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate Use Criteria for Cardiac Computed Tomorgraphy, J Am Coll Cardiol; 56 (22): 1864-1894. Negative Does not provide info regarding cardiac ischemia (snapshot) Not as accurate for extensive disease or to detect coronary stent stenosis Radiation dose variability 2007: 5-30 mSv with mean 12 Newer scanners: 1-5 mSv (Annual radiation dose limit for nuclear energy workers= 50 mSV) Less favorably: High risk Routine repeat or general testing Coronary CT Angiography

  30. Level of Diagnostics Coronary Angiogram Second Level Nuclear Echo Magnet Entry Level More invasive More restricted EST CCS CTA

  31. Which Test to Choose? Wait Times Symptoms Patient Age Patient Sex Test Availability Diagnosis Co-morbidities

  32. The Abyss of Nuclear Medicine

  33. Stenotic vessels are unable to dilate in response to stress. Use stress to create difference between normal and stenotic arteries: Exercise stress Pharmacological stress Images differ based on blood flow to region as detected by tracer and camera. Perfusion defects in scans and ST changes on ECG. Nuclear Perfusion Scans Krause,R. (2011). Review of cardiac tests [Electronic version]. Retrieved Oct 17, 2011 from http://emedicine.medscape.com/article/811577-overview#a1

  34. Nuclear Perfusion Scans • Perfusion Defects: reversible (alive) and fixed (dead) • Viability: Thallium only • Estimate LV function: Normal is 50% • LV Volumes • High risk features: • Transient ischemic dilation: large amount of ischemic myocardium to affect wall motion enough that LV enlarges between rest and stress • Area, location, and depth of ischemia • EF change (drop) between rest and stress Carli, M. et al. Jour Nuclear Med (48), 5 - 2007

  35. Stressor Exercise Pharmacological Tracer (Info obtained depends on tracer) Camera Images taken at: Stress Rest Time (Time between images depends on tracer) General Process

  36. Pharmaceutical Stress

  37. Radioactive Different ½ lives Target: myocytes Different mechanism of action Myocardial blood flow Physiological Substrate Concentration of tracer proportional to blood flow and/or physiological activity as detected camera Tracers give off either one or two gamma rays which requires different cameras. Nuclear Perfusion Scans Tracers Lodge, A., Braess, H., Mahmoud, F., et al. (2005). Developments in nuclear cardiology: transition from single photon emission computed tomography to positron emission tomography/computed tomography.[Electronic Version]. J Invasive Cardiol, 17 (9): 491-496. MIBI (Tc-99m)

  38. SPECT Camera PET Camera External Detector Systems Krause. R. et al. Review Cardiac Tests. www.emedicine.medscape.com/article/811577 Lodge, A., Braess, H., Mahmoud, F., et al. (2005). Developments in nuclear cardiology: transition from single photon emission computed tomography to positron emission tomography/computed tomography.[Electronic Version]. J Invasive Cardiol, 17 (9): 491-496. Single Photon Emission Computed Tomography Tracer gives off single gamma ray at lower energy level Issue with tissue penetration (attenuation) Traces myocardial blood flow with no metabolic assessment Positron Emission Tomography Tracer gives off high energytwogamma rays moving in opposite directions “positron” Improved spatial resolution and imaging Integration as physiological substrate measuring metabolism

  39. Nuclear Perfusion Scans Single Photon Emission CT (SPECT) MIBI and Thallium Krause. R. et al. Review Cardiac Tests. www.emedicine.medscape.com/article/811577 Examines blood flow to heart during stress and during rest. Patient population: LBBB, paced, AF, ECG baseline abnormality, cannot exercise, LVH Sensitivity 85% Specificity 70- 81% specific for stenosis over 50%

  40. Nuclear Perfusion Scans Single Photon Emission CT (SPECT) TracersMIBI and Thallium Carli, M., Dorbala, S., Meserve, J., Fakhri, G., Sitek, A., & Moore, S. (2007). Clinical myocardial perfusion PET/CT. J Nucl Med, 48, 783-793.

  41. Nuclear Perfusion Scans Single Photon Emission CT (SPECT) Issues • Attenuation artifact: Obesity, breast tissue, diaphragm Radiation reduced when passes through tissue. • Left breast: anterior defect. • Left diaphragm: inferior wall scar or thinning. 2. Tracer Supply 3. Concept of balanced ischemia: • Triple vessel CAD, LM with high grade RCA. • All areas under perfused. • Other clues: TID, hypotension with exercise 4. Radiation: • MIBI 9-23 mSv (230 CXR) • Thallium: 12-33 mSv (330 CXR) Circulation, 2011; 123;e10

  42. Nuclear Perfusion ScansPositron Emission Tomography (Cardiac PET/CT) Carli, M. et al. Jour Nuclear Med (48), 5 - 2007 Available as study at UAH/MAZ Tracer: Rubidium-82 (RB-82) , K+ analog ½ life is 76 seconds High energy 640 Kev Two gamma rays

  43. Nuclear Perfusion ScansPositron Emission Tomography (PET/CT)Patient Population Same as SPECT LBBB, paced, AF, ECG baseline abnormality, cannot exercise, LVH Better suited for obese

  44. Nuclear Perfusion ScansPositron Emission Tomography (Cardiac PET/CT) Carli, M. et al. Jour Nuclear Med (48), 5 - 2007 • Sensitivity: 92% • Specificity: 85% • Better attenuation correction • Improved spatial resolution • Can obtain viability but need 2nd test with different tracer - FDG • Higher cost • Radiation but much less than SPECT (5-20x) • Concept of balanced ischemia: reduced • ECG gated to assess LV function at rest and peak stress (SPECT post stress) (Normal: EF increases with stress) • Quantifying myocardial perfusion

  45. The Future PET/CT (hybrid scan)

  46. Assessment Chest pain Viability Functional capacity Stress: Exercise Pharmacological Dobutamine +/- Atropine Stress Echocardiography

  47. Peak stress images obtained at 85% of predicted HR: analyzed for wall motion abnormalities Recovery images obtained within 90 seconds of peak Echogenic microbubbles enhances image quality (contrast). Sensitivity 79% Specificity 87% Stress Echocardiography Krause. R. et al. Review Cardiac Tests. www.emedicine.medscape.com/article/811577

  48. Stress Echocardiography Patient Population Obesity Variable results with lung disease and tachycardia as can limit image quality Non-diagnostic EST Probable false + on EST Younger and females ECG abnormalities Permanent pacemaker LVH

  49. Stress Echocardiography Positive Results Stress induced decrease in regional wall motion Decreased wall thickening Regional compensatory hyperkinesis Krause. R. et al. Review Cardiac Tests. www.emedicine.medscape.com/article/811577

  50. Advantages Disadvantages Stress Echocardiography Complete assessment of LV No radiation Portable Results quicker Cost lower than nuclear Additional information i.e. Valves, structure • Result accuracy operator dependent • Quality affected by: • Body habitus • Acoustic windows but can be improved with contrast Krause. R. et al. Review Cardiac Tests. www.emedicine.medscape.com/article/811577

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