Interpreting Stress Induced Ischemia by ECG, Bundle Branch Block & Arrhythmias Disclosure Gregory S Thomas MD, MPH Medical Director, MemorialCare Heart & Vascular Institute, Long Beach Memorial Astellas speakers bureau and consultant Clinical Professor, UC Irvine gthomas1@memorialcare.org Long Beach Memorial 1.The most prominent feature of atrial fibrillation is: 1. The rhythm is irregularly, irregular 2. The QRS complex is always wide 3. The ventricular rate does not go faster than 100 bpm 4. Patients always feel palpitations when they are in atrial fibrillation 2. ST depression criteria for ischemia recommended by the Ellestad Stress Testing textbook is: 1. 2 mm of ST depression: horizontal, downsloping or upsloping 2. 1.5 mm of ST depression: horizontal, downsloping or upsloping 3. 1 mm of ST depression: horizontal, downsloping or upsloping 4. 1 mm of ST depression, horizontal, downsloping or 1.5 mm of upsloping ST depression 3. ST depression indicative of ischemia is most commonly observed in leads: 1. V1-V2 2. I and avl 3. V4-5 4. II and III 4. ST elevation occurring during exercise stress in leads without Q waves is indicative of: 1. an acute myocardial infarction 2. no important new information 3. transmural ischemia 4. old myocardial infarction
Mason and Likar leads allowed 12 lead monitoring during exercise Arthur Master Bob Bruce Multistage treadmill Myrv Ellestad Lead positions adapted from Mason and Likar. It is important that the right and left arm electrodes not be placed medially near the sternum. Bruce et al. Exercise testing in adult normal subjects and cardiac patients Pediatrics 1963;32 (suppl):742-56 Mason RE, Likar I, Biern RO, Ross RS. In: Blackburn H, editor. Measurements in Exercise Electrocardiography. Springfield, IL: Charles C. Thomas; 1969. p. 445-55 Exercise protocols Exercise protocols Ellestad MH. Stress testing: Principles and Practice. Oxford University Press. 2003 Ellestad MH. Stress testing: Principles and Practice. Oxford University Press. 2003 Borg scale In many patients, particularly those younger and not on medication, a zero can be added to the Borg score to estimate the patient s exertional heart rate. https://www.pftforum.com/blog/treadmill-protocols/ Borg GA: Med Sci Sports Exerc 1982;14(5):377-381.29
Proper posture on a treadmill Resting ECG interpretation Erect posture is all important Ellestad MH. Stress testing: Principles and Practice. Oxford University Press. 2003 Cardiac Conduction System Cardiac Conduction System LA LA RA RA Left Bundle RV LV RV LV Right Bundle Waves Cardiac Conduction System PR Interval P wave P wave Atrial activation T wave QRS complex Ventricular repolarization Ventricular activation QRS Complex and T wave
Intervals Normal 12 Lead ECG ST PR AV nodal conduction 100-200ms QT Repolarization ~350-400ms QRS ventricular activation 90-120ms Rate and Intervals Heart Rate 0.2 sec 0.04 sec 200 msec 40 msec 150 75 300 100 60 1 second Can measure the rate by the distance between QRS complexes Rate Normal: 60-100 beats/min Bradycardia: <60 beats/min Tachycardia: >100 beats/min Rhythm ECG leads Limb leads signify the direction of electricity longitudinally in the body Regular vs. Irregular Supraventricular (narrow QRS <.12 sec) Ventricular (wide QRS >.12 sec)
ECG leads Limb leads signify the direction of electricity longitudinally in the body Precordial (chest) leads Placed across the chest Signifies direction of electricity from the heart to the chest surface to that position of the lead Rhythm P waves Represents atrial electrical activity If marching in front of QRS waves, almost always indicates a sinus rhythm The lack of P waves generally indicates atrial fibrillation or flutter Atrial fibrillation Atrial fibrillation Irregularly irregular ventricular response If substantial variation in the R to R interval is present gating problems gating problems also seen with frequent PVC s or PAC s Atrial fibrillation
Conduction Electricity moving through the left ventricle causes the QRS complex. If conduction is normal QRS complex is < 0.08 seconds long. Right Bundle Branch Block Rabbit ears in V1 or V2 a double peak in the R complex in V1 or V2 caused by the slow conduction over the right side of the heart V1 and V2 sit over the right ventricle Conduction lasting > 0.12 seconds = Block RBBB RBBB Left Bundle Branch Block LBBB Slow upstroke of the R wave in V6 V6 sits over the left side of the heart LBBB + stress with increased heart rate results in increased incidence of reversible septal and anterior defects
ST segment LBBB ST segment Acute transmural MI new ST elevation in the leads placed above the infarct. Subendocardial ischemia results in ST depression most commonly seen in the chest leads over the left ventricle, leads V4 and V5 90% of the ischemic changes on a treadmill test are seen in leads V4 and V5. ST segment represents the electricity between the QRS complex and the T wave Large old MI s often cause chronic ST elevation in the leads above the infarcted area of the left ventricle Q waves typically seen in these same leads Stress ECG Interpretation: Criteria for Ischemia 1. Horizontal or downsloping ST segment depression >1 mm measured 80 msec compared to PR interval 2. Upsloping ST segment depression >1.5mm at 80ms 3. If ST depression is present at rest, than an increase is ST depression of >1 mm at 80 sec Ellestad MH. Stress testing: Principles and Practice. Oxford University Press. 2003 Evaluating the ST segment 1.0 mm downsloping or horizontal or 1.5 mm upsloping Thomas GS. Ellestad MH. in Hurst textbook of cardiology, 2017 Ellestad MH. Stress Testing: Principles and Practice. New York, New York: Oxford University Press; 2003.
ST segment changes during Exercise ECG 2 mm ST segment depression A. Normal B. Upsloping ST segment depression returns to baseline within 80ms C. Upsloping ST segment depression > 1.5mm remains below baseline at 80ms D. Horizontal ST segment depression >1mm E. Downsloping ST segment depression >1mm F. ST segment elevation Tavel, M. E. Chest 2001;119:907-925 ST elevation with exercise in a lead with a Q wave- nonspecific Ellestad MH. Stress Testing: Principles and Practice. New York, New York: Oxford University Press; 2003. Ellestad MH. Stress Testing: Principles and Practice. New York, New York: Oxford University Press; 2003. ST elevation in a lead with an R wave and no Q wave during exercise = transmural ischemia, dangerous Ellestad MH. Stress Testing: Principles and Practice. New York, New York: Oxford University Press; 2003. Bruce protocol + cath 1 mm Downsloping 1 mm Horizontal 1.5 mm Upsloping Goldschlager N, et al. Ann of Int Med 1976;85(3):277-86. Goldschlager N, et al. Ann of Int Med 1976;85(3):277-86.
What occurred in recovery among patients who had upsloping ST depression during exercise Goldschlager N, et al. Ann of Int Med 1976;85(3):277-86. Of all ischemic changes that occurred in recovery, when did they 1st occur? 0-30 sec 30% 30-60 sec 26% by 2 min 26% by >3 min 17% Goldschlager N, et al. Ann of Int Med 1976;85(3):277-86. Case Presentation Exercise test # 1 Of all ischemic changes that occurred in recovery, when did they 1st occur? 44 yo male atypical chest pressure at rest 0-30 sec 30% 30-60 sec 26% by 2 min 26% by >3 min 17% with occasional palpitations Also, the longer the duration of ischemic changes in recovery, the more severe the CAD on cath Goldschlager N, et al. Ann of Int Med 1976;85(3):277-86. Resting ECG HR 70 Stress ECG HR 150 88% PMHR
Arrhythmia Case 1 50 yo male hypertensive, hypercholesterolemia What is the Rhythm? Atrial Fibrillation Type a quote here. Irregular rhythm, no P waves Johnny Appleseed Arrhythmia Case 2 What is the rhythm? 37 yo woman for adenosine stress MPI History of palpitations
Atrial Flutter Atrial Flutter s Atrial Flutter Atrial Flutter I I III II III II avf avf Atrial Flutter Atrial Flutter I I II II avf avf Inferior leads see circular movement
Atrial Flutter Case Presentation Exercise test # 2 sawtooth pattern Resting ECG HR 70 Wide Complex Early into exercise stress Wide Complex Left Bundle Branch Block
Rate-Related Bundle Branch Block LBBB or RBBB may occur as the heart rate increases (rate related) Sudden increase in QRS complex width Typically occurs at a specific HR as the heart rate increases (e.g. 110 bpm) ECG then becomes nondiagnostic for ischemia if LBBB LBBB may cause a false positive MPI with a septal or anterior reversible defect LBBB O Keefe AHJ 1992;124:614 IVCD Nonspecific intraventricular conduction defect QRS process > 0.12 seconds but without rabbit ears or a slow upstroke in V6 Exercise to maximum effort The patient should exercise until exhausted by fatigue. Bruce RA, et al. Pediatrics. 1963;32:Suppl 742-56.
Exercise to maximum effort Exercise to maximum effort Iskandrian and colleagues found MPI sensitivity to be 20% less among patients who achieved a heart rate <85% of MPHR compared to those who achieved >85% MPHR or who stopped upon reaching an ischemic endpoint. Cumming compared submaximal to maximal bicycle exercise testing in 63 subjects who had an abnormal ECG response during maximal exercise or during recovery from maximal exercise. While all were ischemic by ECG at maximum exercise or in recovery, ischemic ECG changes were present at heart rates < 86% of MPHR in only approx 50% of subjects. 1. Iskandrian AS et al JACC 1989;14(6):1477-86.. Bumming GR. British Heart Journal. 1972;34:919 Exercise to maximum effort Mohit Jain and colleagues at Yale evaluated 232 patients who had ischemic electrocardiogram at peak exercise and who exercised for >1 min beyond the time at which they achieved >85% MPHR. Exercise testing: Factors that predict prognosis At 85% MPHR the electrocardiogram was ischemic in only 144 (62%) patients. Mean ST segment depression was 1.2 mm at 85% MPHR and 2.3 mm at peak exercise. Jain M, et al. JNC 2011;18(6):1026-35 Ischemic ECG changes predict mortality Robb GP, Marks HH. JAMA 1967;200(11):918-26 Robb GP, Marks HH. JAMA 1967;200(11):918-26
Increasing ST depression predicts mortality Robb GP, Marks HH. JAMA 1967;200(11):918-26 Predicting severity of CAD by time of onset of ECG changes Goldschlager N et al Ann Int Med 1976;85:277-86. Goldschlager N et al Ann Int Med 1976;85:277-86. Predicting severity of CAD by how long ECG changes last Goldschlager N et al Ann Int Med 1976;85:277-86. Chest pain associated with ST depression predicts worsened outcome Cole JP, Ellestad MH. AJC 1978;41:227-32. Cole JP, Ellestad MH. AJC 1978;41:227-32.
Recovery Dimsdale JE, et al. JAMA 1984;251:630-632 Norepinephrine during exercise & recovery ST depression in recovery predicts 6 year outcomes of coronary death, nonfatal MI or angina n= 1,500 total, 214 with ST depression Dimsdale JE, et al. JAMA 1984;251:630-632 Rywik TM, et al. Circulation. 1998;97(21):2117-22. Sress testing summary Abnormal ST depression = 1.0 mm downsloping or horizontal or 1.5 mm upsloping Downsloping ST depression worse than horizontal, which is worse than upsloping Prolonged ST depression worse prognosis If significant ECG changes of ST depression and MPI is normal, be considered about ischemia. Consider Calcium scoring or further testing 1.The most prominent feature of atrial fibrillation is: 1. The rhythm is irregularly, irregular 2. The QRS complex is always wide 3. The ventricular rate does not go faster than 100 bpm 4. Patients always feel palpitations when they are in atrial fibrillation The patient should exercise to maximum capacity, not just to 85% MPHR ST changes in recovery are as predictive as with exercise
1.The most prominent feature of atrial fibrillation is: 1. The rhythm is irregularly, irregular 2. The QRS complex is always wide 3. The ventricular rate does not go faster than 100 bpm 4. Patients always feel palpitations when they are in atrial fibrillation The correct answer is 1, the rhythm of atrial fibrillation is irregularly irregular. It follows no pattern. The QRS in atrial fibrillation is typically narrow but may be wide if the patient has a bundle branch block. The ventricular rate can be 40-200 bpm. Patients may be asymptomatic when they are in atrial fibrillation. Reference: 2. ST depression criteria for ischemia recommended by the Ellestad Stress Testing textbook is: 1. 2 mm of ST depression: horizontal, downsloping or upsloping 2. 1.5 mm of ST depression: horizontal, downsloping or upsloping 3. 1 mm of ST depression: horizontal, downsloping or upsloping 4. 1 mm of ST depression, horizontal, downsloping or 1.5 mm of upsloping ST depression Wagner GS, Strauss DG. Marriott s Practical Electrocardiography. Lippincott. 2013 2. ST depression criteria for ischemia recommended by the Ellestad Stress Testing textbook is: 1. 2 mm of ST depression: horizontal, downsloping or upsloping 2. 1.5 mm of ST depression: horizontal, downsloping or upsloping 3. 1 mm of ST depression: horizontal, downsloping or upsloping 4.1 mm of ST depression, horizontal, downsloping or 1.5 mm of upsloping ST depression The correct answer is 4. The standard Ellestad text, published since 1975, uses 1 mm of ST depression, horizontal, downsloping or 1.5 mm of upsloping ST depression as criterion for ischemia. 3. ST depression indicative of ischemia is most commonly observed in leads: 1. V1-V2 2. I and avl 3. V4-5 4. II and III Reference: Ellestad MH. Stress testing: Principles and practice. 5th ed. Oxford ; New York: Oxford University Press; 2003. 3. ST depression indicative of ischemia is most commonly observed in leads: 1. V1-V2 2. I and avl 3. V4-5 4. II and III The correct answer is 3, 90% of the ischemic changes are seen in leads V4 and V5. Changes in leads V1-V2 and L and avl are infrequent. When ST depression is present in the inferior leads, II, III and avf, it is often a false positive test. References: 4. ST elevation occurring during exercise stress in leads without Q waves is indicative of: 1. an acute myocardial infarction 2. no important new information 3. transmural ischemia 4. old myocardial infarction Ellestad MH. Stress testing: Principles and practice. 5th ed. Oxford ; New York: Oxford University Press; 2003
4. ST elevation occurring during exercise stress in leads without Q waves is indicative of: 1. an acute myocardial infarction 2. no important new information 3. transmural ischemia Thank you 4. old myocardial infarction The correct answer is 3, transmural ischemia. ST elevation occurring during exercise stress testing in contiguous leads without Q waves (except in avr and V1-2) indicates transmural (full thickness) myocardial ischemia. A high-grade proximal coronary lesion typically supplies the ischemic and often portends an unfavorable outcome. ST elevation during exercise in contiguous leads with an R wave localizes to the coronary artery involved. For example, ST elevation in V2-4 suggests a high grade proximal left anterior descending artery stenosis. References: Ellestad MH. Stress testing: Principles and practice. 5th ed. Oxford ; New York: Oxford University Press; 2003. xi, 546 pp. Akil S, Sunnersjo L, Hedeer F, Heden B, Carlsson M, Gettes L, et al. Stress-induced ST elevation with or without concomitant ST depression is predictive of presence, location and amount of myocardial ischemia assessed by myocardial perfusion SPECT, whereas isolated stress-induced ST depression is not. J Electrocardiol. 2016;49(3):307-15.