EXERCISE STRESS ELECTROCARDIOGRAPHY Dr Tahsin N EXERCISE PHYSIOLOGY

EXERCISE STRESS ELECTROCARDIOGRAPHY Dr. Tahsin N

EXERCISE PHYSIOLOGY Sympathetic activation Parasympathetic withdrawal Vasoconstriction, except- Exercising muscles Cerebral circulation Coronary circulation ↑nor epinephrine and renin

EXERCISE PHYSIOLOGY ↑ventri contractility ↑O 2 extraction(upto 3) ↓peripheral resistance ↑SBP, MBP, PP DBP –no significant change Pulm vasc bed can accommodate 6 fold CO CO - ↑ 4 -6 times

EXERCISE PHYSIOLOGY Isotonic exercise(cardiac output) Early phase- SV+HR Late phase-HR

↑ Exercise work ↑ O 2 usage Person’s max. O 2 consumption (VO 2 max) reached V 02 peak Oxygen consumption (liters/min) Work rate (watts)

The slope of the o 2–work relationship is a measure of the biochemical efficiency of exercise V o 2 max is the product of maximal arteriovenous oxygen difference and cardiac output The V o 2 max depends on Age Men than in women Genetic factors Cardiovascular impairment Physical inactivity.

The ability to deliver O 2 to muscles and muscle’s oxidative capacity limit a person’s VO 2 max. Training ↑ VO 2 max V 02 peak (trained) 70% V 02 max (trained) V 02 peak (untrained) Oxygen consumption (liters/min) 100% V 02 max (untrained) 175 Work rate (watts)

Respiration during exercise • During dynamic exercise of increasing intensity, ventilation increases linearly over the mild to moderate range, then more rapidly in intense exercise • Workload at which rapid ventilation occurs is called the ventilatory breakpoint (together with lactate threshold) Lactate acidifies the blood, driving off CO 2 and increasing ventilatory rate

BLOOD PRESSURE (BP) ALSO RISES IN EXERCISE • Systolic pressure (SBP) goes up to 150 -170 mm Hg during dynamic exercise; diastolic scarcely alters • In isometric (heavy static) exercise, SBP may exceed 250 mm. Hg, and diastolic (DBP) can itself reach 180

Intense exercise Glycolysis>aerobic metabolism ↑ blood lactate (other organs use some) Blood lactic acid (m. M) Relative work rate (% V 02 max) Lactate threshold; endurance estimation

MAXIMUM HR HR=220 - age in years

POST EXERCISE PHASE Vagal reactivation Imp cardiac deceleration mech ↑in well trained athletes Blunted in CCF

MET • Metabolic Equivalent Term • 1 MET = "Basal" aerobic oxygen consumption to stay alive = 3. 5 ml O 2 /Kg/min • Differs with thyroid status, post exercise, obesity, disease states

KEY MET VALUES 1 MET = "Basal" = 3. 5 ml O 2 /Kg/min 2 METs = 2 mph on level 4 METs = 4 mph on level < 5 METs = Poor prognosis if < 65; 10 METs = same progn with medical thpy as CABG 13 METs = Excell prognosis, regardless of othr exercise responses

KEY MET VALUES 3 -5 METs: Raking leaves, light carpentry, golf, 3 -4 mph 5 -7 METs: Exterior carpentry, singles tennis >9 METs: Heavy labour, hand ball, squash, running 6 -7 mph

CALCULATION OF METS ON THE TREADMILL METs = Speed x [0. 1 + (Grade x 1. 8)] + 3. 5 Calculated automatically by Device! Note: Speed in meters/minute conversion = MPH x 26. 8 Grade expressed as a fraction

TREADMILL PROTOCOL Bruce protocol Naughton protocol Weber protocol ACIP(asymptomatic cardiac ischemia pilot) Modified ACIP

PROTOCOL DESCRIPTION (BRUCE) Stage Time (min) M/hr Slope 1 0 1. 7 10% 2 3 2. 5 12% 3 6 3. 4 14% 4 9 4. 2 16% 5 12 5. 0 18% 6 15 5. 5 20%

PROCEDURE Standard 12 lead ECG- leads distally Torso ECG + BP Supine and Sitting / standing HR , BP , ECG Before, after, stage end Onset of ischemic response Each minute recovery(5 -10 mints)

PROCEDURE- LEAD SYSTEMS Mason-Liker modification RAD ↑inf lead voltage Loss of Q in inf leads New Q in AVL

CONTRAINDICATIONS TO EXERCISE TESTING Absolute 1) Acute MI (< 2 d) 2) High-risk unstable angina 3) Uncontrolled cardiac arrhythmias causing symptoms hemodynamic compromise 4) Symptomatic severe AS 5) Uncontrolled symptomatic CCF 6) Acute pulmonary embolus or pulmonary infarction 7) Acute myocarditis or pericarditis 8) Acute Aortic dissection or

CONTRAINDICATIONS TO EXERCISE TESTING Relative 1. LMCA stenosis 2. Moderate stenotic valvular heart disease 3. Electrolyte abnormalities 4. Severe HTN 5. Tachyarrhythmias or bradyarrhythmias 6. 7. HOCM and other forms of outflow tract obstruction Mental or physical impairment leading to inability to exercise adequately 8. High-degree AV block

Both MI and deaths have been reported and can be expected to occur at a rate of up to 1 per 2500 tests

CLASSIFICATION OF CHEST PAIN Typical angina 1. Substernal chest discomfort with characterstic quality and duration 2. Provoked by exertion or emotional stress 3. Relieved by rest or NTG Atypical angina Meets 2 of the above characteristics Noncardiac chest pain Meets one or none of the typical characteristics

BAYES' THEOREM A THEORY OF PROBABILITY ‘The post test probability is proportional to the pretest probability’

PRETEST PROBABILITY Based on the patient's history ( age, gender, chest pain ), physical examination and initial testing, and the clinician's experience. Typical or definite angina →pretest probability high - test result does not dramatically change the probability. Diagnostic testing is most valuable in intermediate pretest probability category

PRE TEST PROBABILITY OF CORONARY DISEASE BY SYMPTOMS, GENDER AND AGE

INDICATIONS OF EXERCISE TESTING

TO DIAGNOSE OBSTRUCTIVE CAD Class I Adult patients (including RBBB or <1 mm of resting ST↓) with intermediate pretest probability of CAD Class IIa Patients with vasospastic angina.

TO DIAGNOSE OBSTRUCTIVE CAD Class IIb 1. Patients with a high pretest probability of CAD 2. Patients with a low pretest probability of CAD 3. Patients with <1 mm of baseline ST ↓and on digoxin. 4. Patients with LVH and <1 mm baseline ST ↓.

TO DIAGNOSE OBSTRUCTIVE CAD Class III 1. Patients with the following baseline ECG abnormalities: • Pre-excitation syndrome • Electronically paced ventricular rhythm • >1 mm of resting ST depression • Complete LBBB

IN ASYMPTOMATIC PERSONS WITHOUT KNOWN CAD Class IIa • Evaluation of asymptomatic T 2 DM pts who plan to start vigorous exercise ( C) Class IIb • 1. Evaluation of pts with multiple risk factors as a guide to riskreduction therapy. • 2. Evaluation of asymptomatic men > 45 yrs and women >55 yrs: • • Plan to start vigorous exercise • • Involved in occupations which impact public safety • • High risk for CAD(e. g. , PVOD and CRF) Class III • Routine screening of asymptomatic

RISK ASSESSMENT AND PROGNOSIS IN PATIENTS WITH SYMPTOMS OR A PRIOR HISTORY OF CAD Class I • 1. Initial evaluation with susp/known CAD, including. RBBB or <1 mm of resting ST Depression • 2. Susp/ known CAD, previously evaluated, now significant change in clinical status. • 3. Low-risk UA pts >8 to 12 hrs & free of active ischemia/CCF • 4. Intermed-risk UApts > 2 to 3 days & no active ischemia/ CCF Class IIa • Intermed-risk UA pts – initial markers (N), rpt ECG –no signi change, and markers >6 -12 hrs (N) & no other evidence of ischemia during observation.

AFTER MYOCARDIAL INFARCTION Class I • 1. Before discharge (submaximal --4 to 6 days). • 2. Early after discharge if the predischarge exercise test was not done (symptom limited --14 to 21 days). • 3. Late after discharge if the early exercise test was submaximal (symptom limited --3 to 6 weeks). Class IIa • After discharge as part of cardiac rehabilitation in patients who have undergone coronary revascularization.

AFTER MYOCARDIAL INFARCTION Class IIb 1. Patients with the following ECG abnormalities: • • Complete LBBB • • Pre-excitation syndrome • • LVH • • Digoxin therapy • • >1 mm of resting ST-segment depression • • Electronically paced ventricular rhythm 2. Periodic monitoring in patients who continue to participate in exercise training or cardiac rehabilitation.

AFTER MYOCARDIAL INFARCTION Class III 1. Severe comorbidity likely to limit life expectancy and/or candidacy for revascularization. 2. At any time to evaluate pts with AMI with uncompensated CCF, arrhythmia, or noncardiac exercise limiting conditions. 3. Before discharge to evaluate pts who have already been selected for, or have undergone, cardiac cath. Although a stress test may be useful before or after cath to evaluate or identify ischemia in the distribution of a coronary lesion of borderline severity, stress imaging tests are recommended.

Submaximal protocols • Predetermined end point • Peak HR 120 bpm, or • 70% predicted max HR or • Peak MET - 5 Symptom-limited tests • To continue till signs or symptoms necessitating termination (i. e. , angina, fatigue, ≥ 2 mm of ST↓, ventricular arrhythmias, or ≥ 10 -mm Hg drop in SBP from the resting blood pressure)

BEFORE AND AFTER REVASCULARIZATION Class I • 1. Demonstration of ischemia before revascularization. • 2. Evaluating recurrent symps suggesting ischemia after revascularization. Class IIa • After discharge for activity counseling and/or exercise training as part of rehabilitation in pts aft revascularization.

BEFORE AND AFTER REVASCULARIZATION Class IIb • 1. Detection of restenosis in selected, high-risk asymptomatic pts < first 12 months aft PCI. • 2. Periodic monitoring of selected, high-risk asymptomatic ps for restenosis, graft occlusion, incomplete coronary revascularization, or disease progression. Class III • 1. Localization of ischemia for determining the site of intervention. • 2. Routine, periodic monitoring of asymptomatic pts after PCI or CABG without specific indications.

STRESS TESTING Modality Exercise test Nuclear Imaging Stress Echo Sensitivity Specificity 68% 77% 87 -92% 80 -85% 88 -95%

INVESTIGATION OF HEART RHYTHM DISORDERS Class I • 1. Identification of appropriate settings in pts with rate-adaptive pacemakers. • 2. Evaluation of cong CHB in pts considering ↑activity/competitive sports. (C) Class IIa • 1. Evaluating known or suspected exercise-induced arrhythmias. • 2. Evaluation of medical, surgical, or ablative therapy in exerciseinduced arrhythmias

INVESTIGATION OF HEART RHYTHM DISORDERS Class IIb 1. Isolated VPC in middle-aged pts without other evidence of CAD. 2. Prolonged 1˚AV block or type I-2˚AV block , LBBB, RBBB, or VPC in young pts considering competitive sports. (C) Class III Routine investigation of isolated VPC in young pts.

INTERPRETING TMT

NORMAL ECG CHANGES DURING EXERCISE ↓ PR, QRS, QT ↑ P amplitude Progressive downsloping PR in inf leads j point depression

THE EXERCISE ECG 1 = Iso-electric 2 = J point 3 = J + 80 msec ST 60 -- HR > 130/min ST 80 -- HR ≤ 130/min

CRITERIA FOR READING ST-SEGMENT CHANGES ON THE EXERCISE ECG ST DEPRESSION: Measurements made on 3 consecutive ECG complexes ST level is measured relative to the P-Q junction When J-point is depressed relative to P-Q junction at baseline: Net difference from the J junction determines the amount of deviation When the J-point is elevated relative to P-Q junction at baseline and becomes depressed with exercise: Magnitude of ST depression is determined from the P-Q junction and not the resting J point

Upsloping J point depression of 2 to 3 mm in leads V 4 to V 6 with rapid upsloping ST segments depressed approximately 1 mm 80 msec after the J point. The ST segment slope in leads V 4 and V 5 is 3. 0 m. V/sec. This response should not considered abnormal. be

CRITERIA FOR ABNORMAL AND BORDERLINE ST-SEGMENT DEPRESSION ABNORMAL: 1. 0 mm or greater horizontal or downsloping ST depression at 80 msec after J point on 3 consecutive ECG complexes BORDERLINE: 0. 5 to 1. 0 mm horizontal or downsloping ST depression at 80 msec after J point on 3 consecutive ECG complexes 2. 0 mm or greater upsloping ST depression at 80 msec after J point on 3 consecutive ECG complexes

Normal Rapid Upsloping Minor ST Depression Slow Upsloping

Horizontal Downsloping Elevation (non Q lead) Elevation (Q wave lead)

• In lead V 4 , the exercise ECG result is abnormal early in the test, reaching 0. 3 m. V (3 mm) of horizontal ST segment depression at the end of exercise. • Consistent with a severe ischemic response.

• The J point at peak exertion is depressed 2. 5 mm, the ST segment slope is 1. 5 m. V/sec, and the ST segment level at 80 msec after the J point is depressed 1. 6 mm. • This “slow upsloping” ST segment at peak exercise indicates an ischemic pattern in patients 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 downsloping.

• Becomes abnormal at 9: 30 minutes (horizontal arrow right) of a 12 -minute exercise test and resolves in the immediate recovery phase. • This ECG pattern in which the ST segment becomes abnormal only at high exercise workloads and returns to baseline in the immediate recovery phase may indicate a falsepositive result in an asymptomatic individual without atherosclerotic risk factors.

ST ELEVATION(LOCALISING) Abnormal response – J ↑ ≥ 0. 10 m. V(1 mm) – ST 60 ≥ 0. 10 m. V(1 mm) – Three consecutive beats Q wave lead (Past MI) • Severe RWMA, ↓EF, ↓Prognosis Non Q wave lead (Past MI) • Severe ischemic response Non Q wave lead (No past MI)-1% • Transmural reversible myocardial ischemiavasospasm, ↑coronary narrowing ----

• This type of ECG pattern is usually associated with a full-thickness, reversible myocardial perfusion defect in the corresponding left ventricular myocardial segments and high-grade intraluminal narrowing at coronary angiography. Rarely, coronary vasospasm produces this result in the absence of significant intraluminal atherosclerotic narrowing.

ECG Patterns Indicative of Myocardial Ischaemia ECG Patterns Not Indicative of Myocardial Ischaemia

ECG CHANGES DURING STRESS TEST

ST HEART RATE SLOPE Maximal Heart change in ST with heart rate calculated at the end of each stage rate adjustment of ST segment depression - improve the sensitivity Calculation of the maximal ST/heart rate slope in m. V/beats/min - linear regression An ST/heart rate slope >2. 4 m. V/beats/min - abnormal >6 m. V/beats/min - three-vessel CAD.

THE ST/HEART RATE INDEX Average change of ST segment depression with heart rate throughout the course of the exercise test. >1. 6 - abnormal

CONFOUNDERS OF EXERCISE TREADMILL TEST INTERPRETATION Digoxin Abnormal ST-segment response to exercise In 25% to 40% of healthy subjects Related to age. Left Ventricular Hypertrophy Decreased specificity sensitivity is unaffected. Resting ST Depression Decreased specificity

CONFOUNDERS OF EXERCISE TREADMILL TEST INTERPRETATION Left Bundle-Branch Block Up to 1 cm of ST depression can occur in healthy normal subjects Right Bundle-Branch Block Does not reduce the sensitivity, specificity, or predictive value of the stress ECG Beta Blocker Therapy Reduced diagnostic or prognostic value because of inadequate heart rate response

EARLY REPOLARIZATION AND RESTING ST↑ Return to the PQ junction is normal Hence ST↓ determined from PQ junction Not from the elevated J point before exercise

DUKE TREADMILL SCORE Treadmill Score=Exercise time -5 X (amount of ST-seg. deviation in mm) - 4 X exercise angina index (0 -no angina, 1 angina, 2 if angina stops test). High Risk= -11, mortality >5% annually. Low Risk= +5, mortality 0. 5% annually. Ann Intern Med 1987; 106: 793.

ACC/AHA GUIDELINES: Patients with a high-risk exercise test result (mortality ≥ 4%/yr), should be referred for cardiac catheterization. Pts. with an intermediate-risk result (mortality of 2% to 3%/yr), should be referred for additional testing, either cardiac catheterization, or an exercise imaging study.

PSEUDO NORMALIZATION PATTERN No prior MI Nondiagnostic finding Prior MI Suggests Reversible myocardial ischemia Needs substantiation by rev myo perfusion defect

R WAVE AMPLITUDE LVH Voltage criteria ST seg – less reliable to ∆ CAD even in the absence of LV strain pattern Loss of R wave (MI) ↓Sensitivity of ST response in that lead

U INVERSION Occasionally in precordial leads at HR<120 Relatively nonsensitive Relatively specific

ABNORMAL BP RESPONSE • Failure to ↑SBP >120 mm. Hg • Sustained ↓(15 secs) >10 mm. Hg • ↓SBP below resting BP during progressive exercise Inadequate ↑ of CO 3 VD LMCA disease Cardiomyopathy Arrhythmias Vasovagal LVOT obstruction Hypovolemia Prolonged vigorous exercise

MAXIMUM WORK CAPACITY Important prognostic measurement Work performed in METs Not the no: of minutes of exercise

EXERCISE CAPACITY VO 2 max = (mph x 26. 8) x (0. 1 + [% grade X 1. 8] + 3. 5 1 MET (metabolic equivalent) = 3. 5 ml 0 /kg/min 2 Stage 1 = 5 METS Stage 2 = 6 - 8 METS Stage 3 = 8 -10 METS

EXERCISE CAPACITY “The strongest predictor of the risk of death among both normal subjects, and those with cardiovascular disease”. “Each 1 -MET increase in exercise capacity conferred a 12% improvement in survival”. NEJM 2002; 346: 793 -801.

For each 1 -MET increase in exercise capacity, the survival improved by 12 percent N Engl J Med 2002

EXERCISE CAPACITY In pts. with CAD > 13 METS (Stage IV) prognosis excellent regardless of whether medical or surgical therapy is selected. * Documented CAD, ≥ 2 mm ST-segment depression. Stage IV had a 100% 5 -year survival rate. ** In the Coronary Artery Surgery Study (CASS), patients with 3 -vessel disease, and high exercise capacity (≥ 10 METS), showed no benefit from surgery. (JACC 1986; 8: 741 748) *Circ 1984; 70: 226. **Circ 1982; 65: 482.

HEART RATE RESPONSE Inappropriate ↑ at low work load Anxiety (<1 minute-transient) Persisting several minutes AF Hypovolemia Marginal LV function Physically deconditioned Anemia

HEART RATE RESPONSE Chronotropic incompetence Inability to attain THR OR Abnormal HR Reserve(<80%) {%HR Reserve=(HRpeak-HRrest)/(220 -age- HRrest)} Autonomic dysfunction SN dysfuntion, Drugs Myocardial ischemia ↑long term mortality (not on β blockers)

CHRONOTROPIC INCOMPETENCE Framingham Heart Study Circ 1996; 93: 1520.

HEART RATE RECOVERY During exercise, HR increases due to withdrawal of vagal tone, and increase of sympathetic tone. During recovery, there is a rapid reactivation of vagal tone leading to a decrease in heart rate. Delayed recovery is a marker of poor outcome

HEART RATE RECOVERY Abnormal: 1 minute TMT (upright) < 12 bpm TMT (supine) < 18 bpm An upright value <22 bpm at 2 minutes is abnormal Poor prognosis independent of other factors

EXERCISE INDUCED CHEST DISCOMFORT Usually after ischemic ST changes May be associated with increased DBP In some, only chest discomfort In CSA, CP less freq than ST↓ Angina with no ST ↓- MPI useful to assess ischemic severity.

ANGINA DURING STRESS TEST Mortality (+) ve Stress Test with angina 5%/yr. (+) ve Stress Test, no angina 2. 5%/yr. Circ 1984; 70: 547 -551.

MARKEDLY POSITIVE STRESS TEST 1. ECG changes in the first three minutes. 2. ECG changes that last through recovery. 3. Hypotensive response.

ADVERSE PROGNOSIS & MULTIVESSELCAD 1. Symptom limiting exercise < 5 METs 2. Abnormal BP response 3. ST↓≥ 2 mm or downsloping ST↓ <5 METs, ≥ 5 leads, persisting ≥ 5 mins into reco 4. ST↑ 5. Angina at low exercise work loads 6. Reproducible sustained/symptomatic VT

INDICATIONS FOR TERMINATING EXERCISE TESTING Absolute indications 1. Drop in systolic BP >10 mm Hg from baseline when accompanied by other evidence of ischemia 2. Moderate to severe angina 3. ↑ CNS sympts (ataxia, dizziness, or near-syncope) 4. Signs of poor perfusion (cyanosis or pallor) 5. Technical difficulties in monitoring ECG or systolic BP 6. Subject’s desire to stop 7. Sustained VT 8. ST ↑ (≥ 1. 0 mm) in leads without Q-waves (other than V 1 or a. VR)

INDICATIONS FOR TERMINATING EXERCISE TESTING Relative indications 1. 2. ↓ in systolic BP (≥ 10 mm Hg) in the absence of other evidence of ischemia ST or QRS changes such as excessive ST↓ (>2 mm of horizontal or downsloping ST↓ ) or marked axis shift 3. Arrhythmias other than sustained VT, including multifocal PVCs, triplets of PVCs, SVT, heart block, or bradyarrhythmias 4. Fatigue, shortness of breath, wheezing, leg cramps, or claudication 5. Development of BBB or IVCD that cannot be distinguished from VT 6. Increasing chest pain 7. Hypertensive response

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