1. Matthew Schumaecker, MD, FACC Assistant Professor of Medicine VTC School of Medicine

2. Objectives Review and be familiar with: 1. the importance of cardiac stress testing 2. imaging modalities of stress testing 3. stress modalities of stress testing 4. Relative specificity and sensitivity of each modality

3. Overview of Stress Modalities Stress ModalityImaging Modality  Exercise Treadmill Bicycle  Pharmacological Dobutamine Atropine Adenosine Dipyridamole  Surface electrocardiography  Echocardiography  Myocardial Perfusion Imaging: SPECT PET

4. Stress Modality: Exercise Advantages:  Least expensive stress modality  Lowest concern for adverse reaction  Produces physiologic ischemia in CAD  Threshold of reproduction of ischemic symptoms  Derived functional data is strongly predictive of cardiac mortality Disadvantages:  Cannot perform in patients with significant functional limitations  ECG uninterpretable in LBBB, LVH, resting ST abnormalities, WPW, PPM and SPECT can be false positive in LBBB and patients with PPM

5. Stress Modality: Exercise-Treadmill  Treadmill is most commonly used for exercise  Bicycle is used mostly in echo lab for valve cases (i.e., mitral stenosis) and to assess for exercise-induced pulmonary hypertension.  Patients are put on a standardized protocol which can predict performance based on age and gender (i.e., Bruce, Cornell, Naughton)

6. Stress Modality: Exercise-Treadmill Bruce Protocol - Treadmill  Most commonly used protocol.  Very well-studied and validated with good prognostic data.  Each stage lasts three minutes  Patient exercises to symptomatic maximum Stag e Speed (mph) Gradient (%) I1.710 II2.512 III3.414 IV4.216 V5.018 VI5.520

7. Stress Modality: Exercise  MET = Metabolic equivalent  1 MET = amount of energy expended at supine rest  1 MET ≈ (kcal/hour)/kg  1 MET ≈ 3.5 ml/kg/min VO 2  Average maximum exercise threshold in healthy middle-aged male ~ 10 METS

8. Stress Modality: Exercise-Treadmill

10. Stress Modality: Exercise - Bicycle Advantages  More direct measurement of work (i.e., watts)  Echocardiographic images obtained during exercise  Useful for evaluating mitral stenosis and exercise induced pulmonary hypertension  Can complement vasodilator stress by producing better images and minimizing symptoms  Can obtain respiratory data if equipped Disadvantages  Can be cumbersome to set up.  Takes longer to reach MPHR  Not widely used in US for cardiac stress testing

11. Stress Modality: Dobutamine  Beta agonist  Simulates exercise by positive chronotropy and inotropy.  Can be difficult to achieve 85% MPHR with dobutamine alone  May need to augment chronotropic response with atropine up to 1 mg.  Can cause SAM and LVOT obstruction in patients with significant septal hypertrophy.

12. Stress Modality: Vasodilator Slide by Dr. Robert Hendel. ASNC 7/07

13. Stress Modality: Vasodilator Slide by Dr. Robert Hendel. ASNC 7/07

14. Stress Modality: Adenosine  Causes coronary arteriolar vasodilation  Extremely short half life  Given in a four or six minute infusion  Tracer is injected halfway through the protocol  Can cause flushing, diaphoresis, chest pain. Usually resolves within minutes after infusion

15. Stress Modality: Adenosine  Causes mast cell degranulation and histamine release in asthmatic patients.  Can cause atrioventricular block

16. Stress Modality: Dipyridamole  Trade Name: Persantine  Acts by blocking the cellular uptake of adenosine  Four to ten times less expensive than adenosine  Comparable to adenosine with respect to sensitivity; specificity may be lower  Much longer half life so adverse reactions tend to be more severe

17. Imaging Modalities Slide by Dr. Robert Hendel. ASNC 7/07

18. Imaging Modalities: Sensitivity and Specificity

19. Surface ECG  Obtained during every stress modality.  Determine underlying rhythm  Assess for arrhythmic response to stress  Assess for ischemic response to stress ST segment is monitored during all phases of stress to look for significant deviation.  Sensitivity and specificity alone are lower than other modalities (especially in women) but can be complementary to other modalities.

20. ECG Positivity Tak and Gutierrez. Postgraduate Medicine Online June 2004

21. Treadmill Echo  Lower sensitivity than other tests  Get additional prognostic data with exercise  Technically challenging – images should all be aqcuired within 90 seconds and within 10% of peak heart rate

22. Dobutamine Echo

23.  Dobutamine is infused at 20, 30, 40 and 50 mcg/kg/min  Dobutamine can test for viability (i.e., biphasic response)  Dobutamine images are collected in real time  Dobutamine can give information about aortic stenosis  Sensitivity of 84%; specificity of 87%  Robust transplant literature surrounding DSE

24. SPECT

25. New Frontiers  PET  Adenosine MRI  Adenosine Echo  Echo microbubble perfusion imaging