Exercise stress electrocardiography

Exercise stress electrocardiography

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

O2 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 O2 usage Persons max. O2 consumption (VO2max) reached V02 peak

Oxygen consumption (liters/min) Work rate (watts) The slope of the o2work relationship is a measure of the biochemical efficiency of exercise V o2max is the product of maximal arteriovenous oxygen difference and cardiac output

The V o2max depends on Age Men than in women Genetic factors Cardiovascular impairment

Physical inactivity. The ability to deliver O2 to muscles and muscles oxidative capacity limit a persons VO2max. Training VO2max V02 peak 70% V02 max (trained) (trained) V02 peak Oxygen consumption (liters/min) (untrained)

100% V02 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 CO2 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 mmHg, and diastolic (DBP) can itself reach 180

Intense exercise Glycolysis>aerobic metabolism blood lactate (other organs use some) Blood lactic acid (mM) Relative work rate (% V02 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 O2 /Kg/min

Differs with thyroid status, post exercise, obesity, disease states 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; 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 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 2 3 4 5 6 0 3 6 9 12 15

1.7 2.5 3.4 4.2 5.0 5.5 10% 12% 14% 16% 18% 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 or 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 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 Age Gender Typical/Definite Angina Pectoris

Atypical/Probable Angina Pectoris NonAnginal Chest Pain Asymptomatic 30-39 30-39 Males Intermediate Intermediate low (<10%)

Very low (<5%) Females Intermediate Very Low (<5%) Very low Very low 40-49 Males High (>90%)

Intermediate Intermediate low 40-49 Females Intermediate Low Very low Very low 50-59

Males High (>90%) Intermediate Intermediate Low 50-59 Females Intermediate Intermediate

Low Very low 60-69 Males High Intermediate Intermediate Low 60-69 Females

High Intermediate Intermediate Low High = >90% Intermediate = 10-90% Very Low = <5% Low = <10% 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 T2 DM pts who plan to start vigorous exercise ( C)

Class IIb 1. Evaluation of pts with multiple risk factors as a guide to risk-reduction 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, includingRBBB 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 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

Sensitivity Exercise test 68% Nuclear Imaging Stress Echo Specificity 77% 87-92% 80-85% 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 exercise-induced arrhythmias INVESTIGATION OF HEART RHYTHM DISORDERS Class IIb 1. Isolated VPC in middle-aged pts without other evidence of CAD. 2. Prolonged 1AV block or type I-2AV 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 V4 to V6 with rapid upsloping ST segments depressed approximately 1 mm 80 msec after the J point. The ST segment slope in leads V4 and V5 is 3.0 mV/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 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.

The J point at peak exertion is depressed 2.5 mm, the ST segment slope is 1.5 mV/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 12minute 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 false-positive result in an asymptomatic individual without atherosclerotic risk factors.

ST ELEVATION(LOCALISING) Abnormal response J 0.10mV(1 mm) ST 60 0.10mV(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 change in ST with heart rate calculated at the end of each stage Heart rate adjustment of ST segment depression - improve the

sensitivity Calculation of the maximal ST/heart rate slope in mV/beats/min - linear regression An ST/heart rate slope >2.4 mV/beats/min - abnormal >6 mV/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 -5X (amount of ST-seg. deviation in mm) - 4X 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 mmHg Sustained (15 secs) >10mmHg

SBP below resting BP during progressive exercise Inadequate of CO 3VD 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 2 0 /kg/min 1 MET (metabolic equivalent) = 3.5 ml 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 3vessel disease, and high exercise capacity ( 10 METS), showed no benefit from surgery. *Circ 1984;70:226. **Circ 1982;65:482. (JACC 1986;8:741 748) HEART RATE RESPONSE Inappropriate at low work load Anxiety (<1minute-transient)

Persisting several minutes AF Physically deconditioned Hypovolemia Marginal LV function Anemia HEART RATE RESPONSE Chronotropic incompetence Inability to attain THR OR Abnormal HR Reserve(<80%) {%HR Reserve=(HRpeak-HRrest)/(220-ageHRrest)} Autonomic dysfunction Drugs

SN dysfuntion, Myocardial ischemia long term mortality (not on 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 & MULTIVESSEL CAD 1. Symptom limiting exercise < 5METs 2. Abnormal BP response

3. ST2mm or downsloping ST <5METs, 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. Subjects desire to stop 7. Sustained VT 8. ST (1.0 mm) in leads without Q-waves (other than V1 or aVR) INDICATIONS FOR TERMINATING EXERCISE TESTING

Relative indications 1. in systolic BP (10 mm Hg) in the absence of other evidence of ischemia 2. 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 THANK YOU

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