STRESS TESTING FOR CORONARY ARTERY DISEASE: WHAT IS THE BEST CHOICE FOR YOUR PATIENT? DAVID R. FRIES, MD, FACC UNIVERSITY CARDIOVASCULAR ASSOCIATES

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1 STRESS TESTING FOR CORONARY ARTERY DISEASE: WHAT IS THE BEST CHOICE FOR YOUR PATIENT? DAVID R. FRIES, MD, FACC UNIVERSITY CARDIOVASCULAR ASSOCIATES

2 STRESS Any stimulus, as fear or pain, that disturbs or interferes with the normal physiological equilibrium of an organism -The Random House College Dictionary-

3 Common Types of Stress Tests Routine Treadmill (ECG only) Exercise Echocardiography Exercise Nuclear Stress Dobutamine Echocardiography Dobutamine Nuclear Stress Adenosine Nuclear Stress STRESS TESTS ARE FREQUENTLY ORDERED TO DETECT MYOCARDIAL ISCHEMIA

4 What Is Myocardial Ischemia? An insufficient supply of blood to the heart, usually due to a blocked artery Asymptomatic ischemia occurs in 4 million Americans high risk for ACS without warning Symptomatic ischemia is characterized by chest pain (angina) & occurs in 7 million Angina is caused by increased O2 demand when the heart is working harder than normal (exercise or emotional stress)

5 The Ischemic Cascade

6 Exercise Treadmill Test (ETT) Attempt to provoke symptoms Assess functional aerobic capacity Evaluate hemodynamic response to exercise Evaluate oxygenation during exercise Assess for exercise-induced arrhythmia Assess for myocardial ischemia Assess control of angina with medical Rx

7 Contraindications to Exercise Acute myocardial infarction within 48 hours USA not yet stabilized with medical therapy Uncontrolled cardiac arrhythmia, which may have significant hemodynamic responses (e.g. ventricular tachycardia) Severe symptomatic aortic stenosis, aortic dissection, pulmonary embolism, and pericarditis Multivessel coronary artery diseases that has a high risk of producing an acute myocardial infarction

8 Exercise Treadmill Test

9 Exercise induced ST-segment depression

10 How good is exercise ECG testing? Gianrossi R, Detrano R, Mulvihill D, et al. Exercise-induced ST depression in the diagnosis of coronary artery disease. Circulation 1989; 80: Meta-analysis of 147 consecutive studies involving 24,074 patients SENSITIVITY SPECIFICITY

11 Sensitivity Comparison of Different Testing Modalities vessel 2 vessel 3 vessel All CAD Stress ECG Stress ECHO Nuclear

12 SPECIFICITY OF DIFFERENT STRESS TESTING MODALITIES Stress Nuclear Stress ECG Stress ECHO

13 ETT - Advantages Reasonable assessment of ischemia, functional capacity and prognosis Equipment readily available Validated results across multiple patient populations

14 ETT - Disadvantages Sensitivity lower than that of stress imaging techniques (important in higher risk populations like DM or established CAD too many false negatives) Specificity poor in FEMALE patients and patients with marked ST-T abnormalities on resting ECG (digoxin use, LBBB, pacemaker, WPW) too many false positives Cannot accurately localize extent or severity of ischemia

15 STRESS ECHO

16 Exercise Echo Incorporates an ETT with pre- and postexercise imaging of the heart Echo imaging focuses specifically on LV wall motion Ischemic territory would be seen as a new wall motion abnormality on stress imaging

17 WHEN COMBINED WITH AN ECHO Full evaluation of a cardiac valves Ability to estimate PA Systolic Pressure Doppler interrogation to determine Diastolic Function Evaluate RV size and function Constriction vs. restriction BOTTOMLINE: If the clinical scenario includes unexplained dyspnea, would strongly recommend an ECHO

18 Exercise echo - Advantages Sensitivity and specificity are comparable with those of exercise nuclear imaging Provides information on the presence and extent of coronary disease Results available immediately Portable Less time commitments, lower cost compared with exercise nuclear imaging Assesses multiple parameters including global and regional ventricular function, chamber size, wall thickness, and valvular function Useful for diagnosing coronary disease in presence of baseline ECG abnormalities

19 Exercise echo - Disadvantages Interpretation subjective and nonstandardized Interpretation difficult when resting wall motion abnormalities exist Images are nondiagnostic due to poor image quality in a significant number of patients Ischemic myocardium can resume function in as little as 10 seconds after exercise so the ischemic moment can be missed if images are obtained too long after exercise completed For patients with LBBB or PPM, guidelines do not recommend exercise echocardiography

20 DOBUTAMINE Involves the injection of dobutamine while the patient is closely monitored. Dobutamine stimulates the heart in a similar way as exercise. Activates beta receptor resulting in increased heart rate and myocardial oxygen demand Works by inducing myocardial ischemia

21 PRE-OPERATIVE RISK STRATIFICATION WITH DOBUTAMINE STRESS ECHO Operative Cardiac Event Rate Ischemia at <60% MPHR Ischemia at >60% MPHR No Ischemia *Mayo Clinic, 530 Patients

22 Dobutamine Echo - Advantages Accurately assesses coronary disease in patients unable to exercise Relatively safe in selected patients, side effects are rapidly reversed by terminating the infusion or by administering beta blocker Accurately detects the threshold of myocardial ischemia Assesses myocardial viability Like exercise echocardiography, assesses multiple parameters including global and regional ventricular function, chamber size, wall thickness, and valvular function

23 Dobutamine Echo - Disadvantages Cannot assess functional capacity Results depend on obtaining good echocardiographic windows, which may be difficult to obtain in obese patients or those with chronic obstructive pulmonary disease Requires extensive experience by reader Labor intensive May cause dangerous ventricular arrhythmias, especially in patients with poor left ventricular function or severe coronary heart disease Contraindicated in patients with symptomatic aortic aneurysm

24 NUCLEAR STRESS TESTING

25 Principles of Nuclear Stress Testing During exercise, healthy coronary arteries dilate more than an artery that has a blockage. The unequal dilation causes more blood to be delivered to heart muscle supplied by the normal artery. In contrast, narrowed arteries end up supplying reduced flow to its area of distribution. When a "perfusion tracer" (a nuclear isotope that travels to heart muscle with blood flow) is injected intravenously, it is extracted by the heart muscle in proportion to the flow of blood.

26 Principles of Nuclear Stress Testing The amount of tracer uptake helps differentiate normal muscle (which receives more of the tracer) from the reduced uptake demonstrated by muscle that is supplied by a narrowed coronary artery. Areas of the heart that have adequate blood flow quickly picks up the tracer material. Muscle with reduced blood flow pick up the tracer slowly or not at all. Analysis of the images of the heart (taken by a scanning camera) can help identify the location, severity and extent of reduced blood flow (ischemia) to the heart.

27 Nuclear Imaging: Assessment of size and severity of Ischemia

28 Myocardial Infarction with small zone of adjacent ischemia

29 Exercise Nuclear - Advantages Well-validated ability to detect severe coronary disease and to assess prognosis Results are reproducible Can assess left ventricular size and systolic function Improved sensitivity and specificity More accurate determinant of extent of coronary disease and prognosis Assesses myocardial viability

30 Exercise Nuclear - Disadvantages Increased cost Requires longer time commitment Modest radiation exposure Specificity depends upon quality control of laboratory and specialty trained readers Artifact due to soft tissue (eg breast) or diaphragmatic signal attenuation may occur Additional equipment and personnel needed In presence of left bundle branch block has low specificity because of high proportion of false positive results

31 Adenosine vs. Regadenoson (Lexiscan) Both bind the A2a adenosine receptor to produce coronary vasodilation Both produce maximal hyperemia quickly Adenosine 30-second half-life Regadenoson 2-3 minute half-life Longer life allows for a single bolus injection, obviating the need for an IV line

32 What about Persantine? Considered an indirect vasodilator Persantine (dypridamole) inhibits the local elimination or uptake of adenosine Increase in the concentration of adenosine Indirect action = slower process than adenosine (max effect 4-5 minutes) Effects (wanted and unwanted) persist for a longer duration than adenosine

33 VASODILATOR NUCLEAR STRESS TESTING NORMAL CORONARY BLOOD FLOW PRESENT IN ABSENCE OF ANY STENOTIC LESIONS RESTING STATE

34 VASODILATOR NUCLEAR STRESS TESTING RESTING STATE ADENOSINE STRESS

35 NORMAL ADENOSINE NUCLEAR SCAN

36 VASODILATOR NUCLEAR DETECTION OF CORONARY ARTERY DISEASE LOCAL VASODILATORS ARE RELEASED IN AN ATTEMPT TO MAINTAIN CORONARY BLOOD FLOW RESTING STATE

37 VASODILATOR NUCLEAR DETECTION OF CORONARY ARTERY DISEASE RESTING STATE ADENOSINE STRESS

38 VASODILATOR NUCLEAR DETECTION OF CORONARY ARTERY DISEASE

39 Vasodilator Nuclear Stress - Advantages Accurately assesses coronary disease in patients unable to exercise Especially useful and validated in preoperative risk assessment in patients with claudication or musculoskeletal limitations Relatively safe in selected patients, side effects are rapidly reversed by terminating the infusion or by administering aminophylline More specific for detecting coronary disease in patients with baseline LBBB than exercise perfusion imaging

40 Vasodilator Nuclear Stress - Disadvantages Cannot assess functional capacity ECG abnormalities less likely to occur compared with exercise testing Contraindicated in hypotension, sick sinus syndrome, high-grade heart block, and in patients with pronounced bronchospastic airway disease or in patients receiving oral dipyridamole therapy Must discontinue theophylline containing medications for 72 hours and caffeine for 24 hours before testing

41 SPECIAL SITUATIONS

42 VASODILATOR STRESS and THREE VESSEL DISEASE LOCAL VASODILATORS ARE RELEASED IN AN ATTEMPT TO MAINTAIN CORONARY BLOOD FLOW RESTING STATE

43 VASODILATOR STRESS and THREE VESSEL DISEASE RESTING STATE ADENOSINE STRESS

44 FALSE NEGATIVE ADENOSINE NUCLEAR SCAN WITH THREE VESSEL DISEASE RESTING STATE ADENOSINE STRESS

45 Left Bundle Branch Block and Stress Testing

46 Left Bundle Branch Block and Stress Testing Abnormal septal motion is noted during stress echocardiography and gated nuclear imaging resulting in decreased accuracy in physician interpretation Reversible defects of the septum are noted during exercise or dobutamine nuclear imaging resulting in increased false positives

47 Left Bundle Branch Induced Septal Defect During Exercise Nuclear Test

48 Left Bundle Branch Block and Stress Testing Bottom line: Stress testing that does not increase heart rate (vasodilator nuclear) is best for patients with Left Bundle Branch Block

49 Nuclear Stress Testing 1 day vs. 2 day Most studies are now performed in one day Low dose Sestamibi (rest images) High dose Sestamibi (stress images) 2-day studies are commonly performed for: Significant soft tissue artifact (breast, GI) Viability assessment

50 TESTING INSTRUCTIONS

51 Testing Instructions ALL STRESS TESTS TROPONIN NEGATIVE! ETT and Exercise Echo Hold beta blockers pm before or day of test (Atenolol, Tenormin, Metoprolol, Lopressor, Toprol, Sotalol, Betapace, Coreg, Carvedilol, Nadolol, Corgard, Inderal, propranolol/la, Bisoprolol, Bystolic, Trandate, Visken, Labetalol, Normodyne, Pindolol) Hold following calcium channel blockers: Diltiazem (Cardiazem, Cartia, Dilacor, Isoptin, Tiazac), Verapamil and Ziac

52 Instructions: Meds to Hold Exercise Nuclear Stress Test No caffeine 24 hours prior to test No smoking 24 hours prior to test No erectile dysfunction meds 48 hours PTT No long acting nitrates or vasodilator x 24 hrs Do not wear nitroglycerine patch day of test Hold CCBs and beta blockers x 24 hrs Hold oral diabetic medications and regular insulin day of test.

53 Instructions: Meds to Hold Adenosine/Lexiscan Stress Test Same as above EXCLUDING the following: Beta and Calcium Channel Blockers can be taken If patient on Theophylline, Dobutamine is warranted (unless otherwise contra-indicated. If so, Theophylline must be held for 24 hours and Adenosine/Lexiscan used with extreme caution). Caffeine: Hold 12 hours for Lexiscan, 24 hours for Adenosine.

54 CONCLUSIONS

55 Questions to Ask When Picking a Test Can the patient exercise on the treadmill or is pharmacological stress testing needed? Can the patient have a routine stress ECG treadmill test or is adjunctive imaging (Nuclear or ECHO) needed? If imaging needed, which one should be used? If pharmacological stress needed instead of exercise, which agent to use?

56 Patients Inappropriate for Routine Exercise Testing Patients unable to exercise > 6 minutes LBBB Pacemaker-dependent Worrisome clinical syndrome Unstable angina Acute MI Uncontrolled cardiac arrhythmia Severe aortic stenosis

57 Questions to Ask When Picking a Test Can the patient exercise on the treadmill or is pharmacological stress testing needed? Can the patient have a routine stress ECG treadmill test or is adjunctive imaging (Nuclear or ECHO) needed? If imaging needed, which one should be used? If pharmacological stress needed instead of exercise, which agent to use?

58 Patients Appropriate for Routine ECG Stress Test without Imaging MALE patients who: Can exercise for 6 or more minutes Normal baseline ECG (No LVH, LBBB or WPW) No Digoxin No history of diabetes No history of coronary revascularization No history of myocardial infarction No unexplained dyspnea

59 Questions to Ask When Picking a Test Can the patient exercise on the treadmill or is pharmacological stress testing needed? Can the patient have a routine stress ECG treadmill test or is adjunctive imaging (Nuclear or ECHO) needed? If imaging needed, which one should be used? If pharmacological stress needed instead of exercise, which agent to use?

60 Situations Where Stress ECHO (in many cases with full echo) Preferred Younger patients with lower likelihood of symptomatic coronary artery disease (fewer false positives) Pericardial Disease suspected Valvular heart disease needs to also be evaluated Need to evaluate for pulmonary hypertension Exertional dyspnea is the predominant complaint

61 Situations Where Nuclear Imaging Preferred Diabetics Previous Myocardial Infarction Reduced LV ejection fraction Left Bundle Branch Block (with Adenosine) Significant COPD (with Dobutamine if unable to exercise) Hospital patient -- positive enzymes (with Adenosine)

62 Situations Where Stress ECHO and Nuclear Probably Equivalent Coronary artery disease patients with preserved LV systolic function and without previous myocardial infarction or diabetes Pre-operative Risk Assessment

63 Questions to Ask When Picking a Test Can the patient exercise on the treadmill or is pharmacological stress testing needed? Can the patient have a routine stress ECG treadmill test or is adjunctive imaging (Nuclear or ECHO) needed? If imaging needed, which one should be used? If pharmacological stress needed instead of exercise, which agent to use?

64 Adenosine is Preferred over Dobutamine EXCEPT in the following situations Echocardiography is chosen imaging modality and patient cannot exercise Patient taking dipyridamole Patient who cannot exercise and are prone to pulmonary bronchospasm Patient with more than first degree heart block

65 Any Questions