Cardiac Diagnostics Workshop. Lori Savard NP Cardiology Update 2015

Transcription

1 Cardiac Diagnostics Workshop Lori Savard NP Cardiology Update 2015

2 Disclosure of Commercial Support Potential for conflict(s) of interest: none

3 Objectives Increase understanding regarding stable IHD and cardiac diagnostics How do we choose the correct test? What information does a specific test provide? What is the appropriate patient population? Apply principles to clinical scenarios.

4 63 Male outpatient CRF: quit smoking 20 years, LDL 2.77 ( no statins) + FHx Annual check up No symptoms Baseline ECG: abnormal ST depression at rest EST: positive Thoughts? Case 1

5 Case 2 68 male with 2 week history of CP 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 PMHx: depression, ECG: LBBB at 68 bpm. B/P: 132/74 BMI: 31

6 Determining Appropriateness as Initial Test 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 ACC/AHA Guidelines for Exercise Testing: Executive Summary

7 Pretest Probability of CAD Age (y) Sex Typical Atypical Non anginal pain Asymptomatic Angina Angina M Intermediate Intermediate Low Very low F Intermediate Very low Very low Very low M High Intermediate Intermediate Low F Intermediate Low Very low Very Low M High Intermediate Intermediate Low F Intermediate Intermediate Low Very low M High Intermediate Intermediate Low F High Intermediate Intermediate Low Probabilities: High > 90%; intermediate 10 90%; low <10%; very low <5%. Adapted from Gibbons et al 2002 ACC/AHA Practice Guidelines

8 Exercise Stress Test 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 texasheartinstitute.org

9 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 May 2002

10 How good is the EST? Sensitivity: probability disease correctly identified. (TRUE) EST: 65 78%. (Mean 68%) 68% Positives correctly identified Specificity: probability a test says someone doesn t have disease which is true. EST: 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 NCSSM Statistics Leadership Institute July 1999 Hill, J. BMJ Volume May 2002 Taylor et al. Can Jour Card 29 (2013) Tak, T. Post Med Online (115) June 2004 No 6

11 Why Bother Exercise Stress Testing? Accessible and relatively inexpensive Provides important prognostic information Duke Treadmill Score (based on minutes Bruce Protocol, ST deviation, angina) Score Risk Annual 5 year Survival Mortality 5 Low 0.25% 97% 10 to +4 Intermediate 1.25% 90% < 11 High 5.25% 65% Adapted from Mark et al. Ann Inter Med 1987;106:793

12 Case 1 62 male with 2 week history of CP 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 PMHx: depression ECG: LBBB at 68 bpm. B/P: 132/74 BMI: 31

13 Choosing Wising Canada Campaign Canadian Cardiovascular Society 2014 Five Things Physicians and Patients Should Question 1. Don t perform stress cardiac imaging or advanced non invasive imaging in the initial evaluation of patients without cardiac symptoms unless high risk markers are present. 2. Don t perform annual stress cardiac imaging or advanced non invasive imaging as part of routine follow up in asymptomatic patients. 3. Don t perform stress cardiac imaging or advanced non invasive imaging as a pre operative assessment in patients scheduled to undergo low risk non cardiac surgery. 4. Don t perform echocardiography as routine follow up for mild, asymptomatic native valve disease in adult patients with no change in signs or symptoms. 5. Don t order annual electrocardiograms (ECGs) for low risk patients without symptoms.

14 Nuclear Perfusion Scans 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. Krause,R. (2011). Review of cardiac tests [Electronic version]. Retrieved Oct 17, 2011 from

15 General Process 1. Stressor Exercise Pharmacological 2. Tracer (Info obtained depends on tracer) 3. Camera Images taken at: Stress Rest 4. Time (Time between images depends on tracer)

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

17 Pharmaceutical Stress Adenosine Dipyridamole Dobutamine (Persantine) Most common Mechanism of Action Dilates coronary vessels 20% increase in heart rate Small but significant drop in blood pressure Blocks reabsorption and metabolism of endogenous adenosine Increases adenosine levels up to 3 4X Direct acting agent Stimulation of the β1 adrenoceptors of the heart to increase contractility and cardiac output Issues Bronchospasm Bronchospasm No bronchospasm Arrhythmias Arrhythmias Arrhythmias Caffeine / theophylline blocks adenosine receptor produce neutral action Caffeine / theophylline blocks adenosine receptor produce neutral action Nonspecific CP Dyspnea Reversal drug aminophylline Reversal drug aminophylline Reference: Journal Nuclear Medicine, Vol.35 No. 4. p Krause, R. Cardiac Tests. Emedicine.medscape. Updated Dec 2013

18 Nuclear Perfusion Scans Tracers 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. Example: One gamma ray: MIBI or Thallium Two gamma rays: PET/CT MIBI (Tc 99m) 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):

19 Nuclear Perfusion Scans Single Photon Emission CT (SPECT) Tracers MIBI and Thallium Tracer Mechanism of Action Characteristic MIBI (Tc 99m) Technetium 99m labeled methoxy isobutyl isonitrite 99m Tc sestamibi Calcium analog enters myoctye Stays in myocyte Does not redistribute so need second injection for second images Gives off single photon Higher energy isotope 140 kev Better image quality and less soft tissue attenuation Thallium (T1 201) Older K+ analog enters viable myocyte: Best uptake first minutes Does not stay in myocyte but redistributes to under perfused areas. This gives us viability information. Gives off single photon Lower energy isotope 83 kev Stays in body longer ½ life 6 hours 73 hours ( 30 days to clear) Total test time Two day 3 4 hours Carli, M., Dorbala, S., Meserve, J., Fakhri, G., Sitek, A., & Moore, S. (2007). Clinical myocardial perfusion PET/CT. J Nucl Med, 48,

20 External Detector Systems SPECT Camera 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 Krause. R. et al. Review Cardiac Tests. Lodge, A., Braess, H., Mahmoud, F., et al. (2005). Developments in nuclear cardiology: transition from single photon emission computed tomography to positron emission bbc.co.uk tomography/computed tomography.[electronic Version]. J Invasive Cardiol, 17 (9):

21 Nuclear Perfusion Scans Single Photon Emission CT (SPECT) MIBI and Thallium 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% Krause. R. et al. Review Cardiac Tests.

22 Nuclear Perfusion Scans Single Photon Emission CT (SPECT) Issues 1. 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) UAH msv Thallium: msv (330 CXR) Circulation, 2011; 123;e10

23 Nuclear Perfusion Scans Positron Emission Tomography (PET/CT) Patient Population Similiar as SPECT LBBB, paced, AF, ECG baseline abnormality, cannot exercise, LVH Better suited for obese

24 Nuclear Perfusion Scans Positron Emission Tomography (Cardiac PET/CT) 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 Carli, M. et al. Jour Nuclear Med (48),

25 External Detector Systems PET Camera Positron Emission Tomography Tracer gives off high energy two gamma rays moving in opposite directions positron Improved spatial resolution and imaging Integration as physiological substrate measuring metabolism Krause. R. et al. Review Cardiac Tests. 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): hamamatsu.com

26 Nuclear Perfusion Scan Positron Emission Tomography (Cardiac PET/CT) Sensitivity: 92% Specificity: 85% Better attenuation correction Improved spatial resolution Can obtain viability but need 2 nd 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 Carli, M. et al. Jour Nuclear Med (48),

27 Case 3 83 Male CRF: HTN, Lipids PMHx: AF, renal insufficiency, TIA, Carotid artery disease, chronic gastritis Chest pain x 10 years: getting worse: Two blocks. CCTA: extensive disease Thoughts?

28 Coronary CT Angiography Krause,R. (2011). Review of cardiac tests [Electronic version]. Retrieved Oct 17, 2011 from 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

29 Coronary CT Angiography 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 Negative Does not provide info regarding cardiac ischemia Not as accurate for extensive disease or to detect coronary stent stenosis Variability Radiation dose 2007: 5 30 msv with mean 12 Newer scanners: 1 5 msv (Annual radiation dose limit for nuclear energy workers= 50 msv) Interpretation Ajlan,A.,Heilbron, B.,& Leipsic, J. (2013). Coronary computed tomography angiography for stable angina: past, present and future. Canadian Journal of Cardiology, 29, Less favorably use: High risk Routine repeat or general testing Bluemke, D., Achenbach, S., Budoff, M et al. (2008).Noninvasive coronary artery imaging Scientific Statement. [Electronic version]. Retrieved June 16, 2009 from ACCF/SCCT/ACR/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate Use Criteria for Cardiac Computed Tomorgraphy, J Am Coll Cardiol; 56 (22):

30 Case 5 43 F : Atypical chest pain CRF: HTN, smoking Hx PMHx: Anxiety EST: non diagnostic

31 Stress Echocardiography Assessment Chest pain Viability Functional capacity Stress: Exercise Pharmacological Dobutamine +/ Atropine

32 Stress Echocardiography Positive Results Stress induced decrease in regional wall motion Decreased wall thickening Regional compensatory hyperkinesis Krause. R. et al. Review Cardiac Tests.

33 Stress Echocardiography 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% Krause. R. et al. Review Cardiac Tests.

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

35 Stress Echocardiography Positives Complete assessment of LV No radiation Portable Results quicker Cost lower than nuclear Additional information i.e. Valves, structure Negatives Result accuracy operator dependent Quality affected by: Body habitus Lung disease Tachycardia Acoustic windows but can be improved with contrast Krause. R. et al. Review Cardiac Tests.

36 Cardiac MR (Stress) High strength magnet and radiowaves Quantitative Assessment Anatomy and systolic function Myocardial tissue pathology: scarring, inflammation, infiltration Stress MR: Ischemia and Infarct Viability disease diagnosis/cardiac mri Taylor et al. Can Jour Card 29 (2013)

37 Patient Population Requires kidney function: egfr > 30 Risk of nephrogenic systemic fibrosis Contraindications: screening form Breath holding ability Claustrophobia issues

38 General Process for Stress MR ( 45 minutes) 1. Stressor (dilate vessels) Pharmacological Adenosine 2. Contrast Gadolinium dye: rare earth metal found only salt form, has paramagnetic properties; chelated form en.wikipedia.org 3. MR Scanner Images taken at: Stress Rest ublic_html/thhic_2011/index.php/services

39 Stress/rest protocol Cardiac Stress MR Comparison stress and rest images Wash in of gadolinium ( 1 st pass): refers to dye entering myocardium ( Turns from black to grey) If area turns slowly, signifies perfusion defect If same area on both rest and stress scans: scar or infarct If only on stress images: ischemia tftcentral.co.uk Taylor et al. Can Jour Card 29 (2013)

40 Cardiac MR Positives Versatility No radiation Non invasive pathology High sensitivity and specificity (85 90%) for detection of ischemia Negatives Detail of coronary anatomy not as good as CCTA Adenosine (Stress MR) Arrhythmia scanning difficulties Availability Cost No option for intervention.yet Taylor et al. Can Jour Card 29 (2013)

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42 Conclusions Multitude of cardiac diagnostics available Test choice influenced by multiple factors Advantages/disadvantages to each test Think about your patient Start with as least invasive test as possible Consider Choose Wisely recommendations

43 Questions?