Dr R.V.S.N. Sarma., M.D., M.Sc., Consultant Physician and Chest Specialist

1. Cardiac Stress Testing Dr R.V.S.N. Sarma., M.D., M.Sc., Consultant Physician and Chest Specialist Visit us at: www.drsarma.in

2. Dedication of this CME To my beloved mother

3. The Spectrum of CAD

4. The important distinction • Slowly progressive CAD • CSA to USA to NSTEMI to STEMI and CVM • Warning ++ long duration • Collateral CBF good • ECG / TMT evidence + • CAG will confirm CAD • Prognosis is good; Older • Non vulnerable plaques • Flow limiting narrowing • Form only 30 % of MI cases • Group with sudden MACE • Give no time to act • SCD or Massive MI • No previous CSA or USA • No warning; Short duration • No time for collateral CBF • TMT/ CAG -ve before MACE • Prognosis is poor; Younger • Vulnerable ruptured plaques • Focus on factors causing rupture • Contribute to 70% of MI cases

5. What is the likelihood of CAD ?

6. Cardiac Stress Tests - Types • Routine Treadmill (ECG only) – ETT or TMT • Stress Echocardiography • Dobutamine Echocardiography (CSE) • Exercise Stress Echocardiography (ESE) • Nuclear Imaging – Chemical Stress - MPI • Dobutamine Nuclear Stress • Adenosine Nuclear Stress • Persantine Nuclear Stress

7. Exercise Treadmill Testing (ETT) • Exercise testing is a well-established procedure • It is in widespread clinical use for many decades • The “how-to” is beyond the scope of this talk • Although ETT is generally a safe procedure, both MI and death have been reported • Occur at a rate of up to 1 per 2500 tests (0.04%) • It is essential to screen and choose the pt for ETT

8. Indications of Exercise Test

9. Some Basics of ETT • Perfect Lead contact – shaving the chest area in men • Should be supervised by a well trained physician, who should be available immediately for emergencies • Careful monitoring & recording in each stage of exercise • The electrocardiogram (ECG) • Heart rate • Blood pressure • And during ST-segment abnormalities and chest pain. • The patient should be monitored continuously • For transient rhythm disturbances, ST-segment changes and • ECG manifestations of myocardial ischemia.

10. The types of Exercise Machines Bicycle Ergo meter Treadmill Test

11. Supine stress test

12. The choice of Exercise Machine • Cycle Ergo meters are generally • Less expensive and smaller • Less noisy than treadmills • ECG disturbances are minimum • But, produce less motion of the upper part of body • The fatigue of the quadriceps muscles is a major limitation • Treadmills are much more commonly used • Supine stress testing is not routinely used

13. Pretest Probability • Age • Gender • Angina • H/o previous MI • Q waves in ECG • Resting ST-T changes • Diabetes • Dyslipidemia • Smoking • Diagnostic Test utility • Most in intermediate probability • Least in high or low probability • Typical Angina • Sub-sternal location • Provoked by exertion or emotion • Relieved by rest/GTN

14. Pre Test Probability of CAD by Symptoms, Gender and Age

15. CAD Testing Algorithm Use a computer model or Use the probability table

16. Testing Algorithm contd..

17. Contraindications for ETT Absolute • Acute myocardial infarction (within 2 days) • High-risk unstable angina • Uncontrolled cardiac arrhythmias • Symptomatic severe aortic stenosis • Uncontrolled symptomatic heart failure • Acute pulmonary embolus or pulmonary infarction • Acute myocarditis or pericarditis • Acute aortic dissection

18. Contraindications for ETT Relative • Left main coronary stenosis • Moderate stenotic valvular heart disease • Electrolyte abnormalities • Severe arterial hypertension • Tachy or Brady arrhythmias • HOCM and other outflow obstructions • Mental or physical impairment • High-degree atrio-ventricular block

19. When to Terminate ETT ? Absolute indications • Drop in SBP of >10 mm Hg from baseline BP with accompanying evidence of ischemia • Moderate to severe angina • Increasing nervous system symptoms ataxia, dizziness • Signs of poor perfusion (cyanosis or pallor) • Technical difficulties in monitoring ECG or SBP • Subject’s desire to stop; Sustained ventricular tachycardia • ST elevation (≥1.0 mm) in leads without diagnostic Q

20. When to Terminate ETT ? Relative indications • Drop in SBP of ≥10 mm Hg BP without ischemia • ST or QRS changes - ST depression (>2 mm of horizontal or down sloping ST-segment ↓) or axis shift • Arrhythmias VT, multifocal PVCs, triplets of PVCs, SVT, • Heart block or brady arrhythmias, BBB or IVCD • Fatigue, shortness of breath, wheezing, leg cramps, IC • Increasing chest pain; Hypertensive response > 250/115

21. Key Points of Exercise Testing • Only Manual SBP measurement for safety • Adjust to clinical history (couch potatoes) • Age predicted Heart Rate Targets ? ? • The BORG Scale of Perceived Exertion • METs - not ‘Minutes’ have to be used • Use standard ECG analysis + 3 minute recovery • Use scores, ST/HR Index, Heart rate recovery • ST segment changes alone will not suffice

22. The measurements in ETT

23. BORG SCALE Talk Test ?

24. What is a MET? • Metabolic Equivalent Term • 1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5 ml O2 /Kg/min -70 kg, 40 yr man • Actually differs with thyroid status, post exercise, obesity, disease states • By convention just divide ml O2/Kg/min by 3.5 METs = Speed x [0.1 + (Grade x 1.8)] + 3.5 3.5 Calculated automatically by Device!

25. Bruce Protocol • Total of 1+6 (Seven 3 minute stages) – (3+18 min) • Each minute exercise is approximately 1 MET • Pretest plain walking + 6 Stages of graded exercise • In each stage there is increase in speed and gradient • Initial 1.7 mph with 10% gradient (upward inclination) • Maximum 5.5 mph with 20% gradient • Modified Bruce – 2 warm up stages (1.7 mph 0%, 5%) • For elderly and patients with reduced exercise capacity

26. The intensity of Exercise

27. Key MET Values • 1 MET = "Basal" = 3.5 ml O2 /Kg/min • 2 METs = 2 mph on level • 4 METs = 4 mph on level • < 5METs = Poor prognosis if < 65 years • 10 METs = Medical Rx as good as CABG • 13 METs = Excellent prognosis • 16 METs = Aerobic master athlete • 20 METs = Super athlete

28. Importance of METs

29. Lead Selection for Analysis • Lead V5 alone consistently outperforms other leads • False + ves are high with the inferior leads • Without prior MI and with normal resting ECGs, the precordial leads alone are a reliable marker for CAD. • Exercise-induced ST-segment  only in inferior leads is not significant for CAD. • Down sloping or horizontal ST-segment  is a stronger predictor of CAD but not up sloping ST 

30. Up Sloping ST J point depression of 2 to 3 mm in leads V4 to V6 with rapid up sloping ST segments depressed approximately 1 mm 80 m sec after the J point. This response should not be considered abnormal.

31. Horizontal ST In lead V4 , the exercise ECG result is abnormal early in the test, reaching 0.3 mV (3 mm) of horizontal ST segment depression at the end of exercise. Consistent with a severe ischemic response.

32. Horizontaland Down sloping ST This “slow up sloping” ST segment at peak exercise indicates an ischemic pattern with a high coronary disease prevalence pretest. A typical ischemic pattern is seen at 3 minutes of the recovery phase when the ST segment is horizontal and 5 minutes after exertion when the ST segment is down sloping. This is typical ischemic response

33. ST Segment Elevation • Early repolarization is a common resting pattern of ST  in normal persons. • Exercise-induced ST-segment  is always considered from the baseline ST level. • ST is seen after a Q-wave infarction, but ST in leads without Q waves occurs in only 1 of 1000 (0.1%) patients of ETT. • ST  is very arrhythmogenic and localizes the IHD

34. MACE (Major Acute Cardiac Events) • MACE : Sudden Cardiac Death (SCD), AMI and USA • Ruptures of high-risk or vulnerable plaques • Inner plaque material is exposed to blood and initiates formation of a platelet-fibrin thrombus on the rupture. • The rupture may seal without detectable sequelae or • The patient may experience ACS or SCD. • Majority of the vulnerable plaques appear insignificant on the CAG ,before rupture (less than 75% stenosis) • Majority of the stenosis > 75% have no vulnerable plaques

35. Prognostic Factors for CAD

36. Exercise Test – BP Response Systolic Blood Pressure x HR = Double Product Example: SBP 170 x HR 160 = 27, 200 Double product must be at least: 20, 000 • SBP should rise > 40 mmHg • Diastolic BP may decline by 10 mm • Drop of > 10 mm in SBP is ominous (Exertional Hypotension)

37. Chronotropic Incompetence • Age Predicted Maximum HR (PrMHR) = (220 – Age in years) • Example: For a 55 years pt Pr MHR = (220-55) = 165 • THR = 90% of Pr MHR of 165 = 148 • Chronotropic Incompetence = < 85% of Pr MHR • In this case 85% of 165 (Pr MHR) = < 140 BPM • Chronotropic Index (CI)= of less than 0.8 is very significant • (HRpeak – HR rest)÷ (PrMHR –HRrest) • If this pt achieved HRpeak of 130 from HRrest of 90 • CI = (130 – 90) ÷ (165 – 90) = 40 ÷ 75 = 0.53 is very low

38. Heart Rate Recovery in ETT Abnormal • If the HR is not reduced by at least 22 BPM from peak exercise heart rate to heart rate measured after 2 minutes. • It is strongly predictive of all-cause mortality.

39. Heart Rate Recovery in ETT

40. Duke Score • Duke score = Exercise time – 5 × (ST-segment deviation in mm) – 4 × Exercise Angina Index (EAI) • Exercise time is based on a standard Bruce protocol • ST deviation is < 1 mm, is taken as 0. • ST deviation = Max exercise ST – Base line ST • E A I value: 0 if no exercise angina 1 if exercise angina occurred 2 if angina severe enough to stop ETT Interpretation contd…

41. Interpretation of Duke Score • High-risk group: The Duke score of  –11 13% of patients fall in this group. Average annual CV mortality  5%. • Intermediate risk : The Duke score of + 4 to – 10 53% of all patients fall in this group Annual CV mortality 0.5% to 4% • Low-risk group: The Duke score of  + 5 34% of patients fall in this group. Average annual CV mortality < 0.5% • For Duke treadmill score Nomogram. See next slide …

42. Nomogram of Duke Treadmill Score This nomogram applies to patients with known or suspected coronary artery disease, without prior revascularization or recent myocardial infarction, who undergo exercise testing before coronary angiography.

43. Prognosis – Duke Score

44. VA Score for men Choose only one per group <40: Low probability 40-60: Intermediate probability >60: High probability

45. VA Score for women Choose only one per group <37: Low probability 37-57: Intermediate probability >57: High probability

46. Can Physicians do as well as the Scores ? 954 patients - clinical/TMT reports Sent to 44 expert cardiologists, 40 cardiologists and 30 MD physicians Scores did always better than all three The experts were the nearest to scores

47. Kaplan Meier Survival Curves for Scores SCORE = (1=yes, 0=no) METs<5 + Age>65 + History of CHF + History of MI or Q wave a=0, b=1, c=2, d=more than 2

48. Confounders of ETT Interpretation

49. Clinical Decision Making

50. GOLD STANDARD SnNOUT (Minimum FN) Sensitivity and Specificity Sensitivity is True positives a Total CAD a + c TEST Specificity is True Negatives d Total No CAD b + d SpPIN (Minimum FP)