Exercise stress ecg. dmo

Exercise stress testing Dr Shivanand Patil

General Applications Diagnosis : Who has coronary artery disease Prognosis : Who is high risk? Who needs intervention Functional assessment : Who is disabled? What activities can be done safely? Treatment assessment : Is medication or intervention effective?

METABOLIC EQUIVALENT Unit of sitting , resting O2 uptake 1 MET = 3.5 ml O 2 / kg / min Measured VO2 =NO.Of METS 3.5ml O2/Kg/min Asses disability Standardize different protocols

ELECTROCARDIOGRAPHIC MEASUREMENTS

Mason –Likar modification Extremity electrodes moved to the torso to reduce motion artifact Arm electrodes - lateral aspects of infraclavicular fossae Leg electrodes -above the anterior iliac crest and below the rib cage

Mason –Likar modification It results in Right axis shift Increased voltage in inferior leads May produce loss of inferior Q waves and development of new Q waves in lead aVL Thus, the body torso limb lead positions cannot be used to interpret a diagnostic rest 12-lead ECG

Baseline Abnormalities - Obscure ECG changes during exercise Left bundle branch block LVH with repolarization abnormality Digitalis Therapy Ventricular paced rhythm WPW syndrome ST abnormality associated with SVT (or) AF ST abnormalities with MVPS and severe anemia

Types of ST Segment Displacement In normal persons The PR, QRS, and QT intervals shorten as heart rate increases P amplitude increases PR segment becomes progressively more downsloping in the inferior leads J point or junctional depression will occur

Types of ST Segment Displacement In patients with myocardial ischemia ST segment usually becomes more horizontal (flattens) as the severity of the ischemic response worsens. With progressive exercise, the depth of ST segment depression may increase, involving more ECG leads, and the patient may develop angina

Types of ST Segment Displacement In the immediate postrecovery phase ST segment displacement may persist, with downsloping ST segments and T wave inversion, gradually returning to baseline after 5 to 10 minutes Ischemic response ---only in the recovery phase Occur in 10 percent of patients Prevalence is higher in asymptomatic populations compared with those with symptomatic CAD

MEASUREMENT OF ST SEGMENT DISPLACEMENT True isoelectric point ----TP segment For purposes of interpretation--- PQ junction is usually chosen as the isoelectric point Abnormal response The development of 1 mm or greater of J point depression with a relatively flat ST segment slope (<1 mV/sec ) depressed greater than or equal to 0.10 mV 80 msec after the J point (ST 80) in three consecutive beats with a stable baseline

MEASUREMENT OF ST SEGMENT DISPLACEMENT When the ST 80 measurement is difficult to determine at rapid heart rates (e.g., >130 beats/min), the ST 60 measurement should be used. The ST segment at rest may occasionally be depressed. When this occurs, the J point and ST 60 or ST 80 measurements should be depressed an additional 0.10 mV or greater to be considered When the degree of resting ST segment depression is 0.1 mV or greater, the exercise ECG becomes less specific, and myocardial imaging modalities should be considered

MEASUREMENT OF ST SEGMENT DISPLACEMENT In early repolarization Normal response---Resting ST segment elevation returns to the PQ junction Magnitude of exercise-induced ST segment depression should be determined from the PQ junction and not from the elevated position of the J point before exercise

MEASUREMENT OF ST SEGMENT DISPLACEMENT Localization of site of myocardial ischemia ST segment depression do not localize the site of myocardial ischemia and which coronary artery is involved ST segment elevation is relatively specific for the territory of myocardial ischemia and the coronary artery involved.

UPSLOPING ST SEGMENTS Normal response J point depression Rapid upsloping ST segment (>1 mV/sec) depressed less than 1.5 mm after the J-point Abnormal response Depression of ST segment > 1.5 mm at ST80 Patients with a high CAD prevalence--- abnormal. Asymptomatic or with a low CAD prevalence--- less certain.

ST SEGMENT ELEVATION ST segment elevation may occur in an infarct territory where Q waves are present in a noninfarct territory. Abnormal response 1 mm elevation at ST60 for 3 consecutive beats with a stable baseline.

ST SEGMENT ELEVATION ST segment elevation in leads with abnormal Q waves Occur in 30% of anterior MI & 15% of inferior MI Have a lower ejection fraction greater severity of resting wall motion abnormalities worse prognosis. not a marker of more extensive CAD rarely indicates myocardial ischemia.

ST SEGMENT ELEVATION ST segment elevation in leads without Q waves Indicates transmural myocardial ischemia caused by coronary vasospasm or a high-grade coronary narrowing Occurring in a 1 percent of patients with obstructive CAD. Site of ST segment elevation is relatively specific for the coronary artery involved

T WAVE CHANGES Pseudonormalization of T waves T-waves inverted at rest and becoming upright with exercise Nondiagnostic finding --- in low CAD prevalence populations In rare instance--- marker for myocardial ischemia

Pseudonormalization of T waves

OTHER ECG MARKERS Changes in R wave amplitude Relatively nonspecific and are related to the level of exercise performed In LVH the ST segment response cannot be used reliably to diagnose CAD U wave inversion may occasionally be seen in the precordial leads at heart rates of 120 beats/min Relatively specific and relatively insensitive for CAD

NONELECTROCARDIOGRAPHIC OBSERVATIONS

Blood Pressure Normal Exercise response SBP - Increase to 160 to 200 mm HG DBP - Does not change significantly In LV dysfunction (or) an excessive reduction in systemic vascular resistance Failure to increase SBP> 120 mm HG (or) Sustained decrease > 10 mm HG (or) Fall in SBP below standing rest values

Exertional Hypotension Ranges from 3 to 9 % Higher in patients with TVD (or) Left main CAD Cardiomyopathy Cardiac arrhythmias Vasovagal reactions LVOT Obstruction On Antihypertensive drugs Hypovolemia Prolonged Vigorous Exercise

Work Capacity Limited work capacity Associated with increased risk of cardiac events in known(or) suspected CAD In estimating functional capacity, the amount of work performed (or exercise stage achieved ) should be the parameter measured and not the number of minutes of exercise

Sub-Maximal Exercise APMHR (Age Predicted Maximum Heart Rate) = 220 - Age Patient should achieve atleast 85 - 90 % of APMHR to test the cardiac reserve Non - Diagnostic Test PVD Orthopedic Limitation Neurological Impairment Poor Motivation

Heart Rate Response Inappropriate increase in heart rate at low exercise workloads Atrial fibrillation Physically Deconditioned hypovolemic Anaemic Marginal LV function

Heart Rate Response Chronotropic incompetence Heart rate increment per stage of exercise that is less than normal (or) a peak rate below predicted at maximal work loads Occurs in sinus node disease Beta Blocker Compensated CCF Myocardial ischemic response

Rate-Pressure Product Heart rate x Systolic BP Product Indirect measure of myocardial oxygen demand increases progressively with exercise used to characterize cardiovascular performance Normal - 20 to 35 mm HG x beats/m x 10 -3 In CAD - < 25 mm HG x beats/m x 10 -3

Chest discomfort It occurs usually after the onset of ischemic ST segment depression In some patients , it may be the only signal of obstructive CAD In CSA , Chest discomfort occurs less frequently than ischemic ST segment depression

Diagnostic use of Exercise testing

Sensitivity and Specificity Both varies with the population being tested Exercise ECG is best used in The evaluation of a patient at intermediate risk with an atypical history (pre-test probability-30-70%) Patient at low risk with a typical history

Sensitivity and Specificity 66% 53% 81% 86% Multivessel CAD Left main or TVD --- 25-71% LAD>RCA>LCx SVD 77% 68% In CAD (General) Specificity Sensitivity Patients

Limitations Bayes theorem The probability of a positive test result is affected by the likelihood (conditional probability) of positive test result among the population that has undergone the test (pretest probability) The higher the probability that a disease is present in a given individual before a test is ordered, the higher is the probability that a test result is true-positive

Noncoronary causes of ST segment depression Severe aortic stenosis Severe hypertension Cardiomyopathy Anemia Hypokalemia Severe hypoxia Digitalis use Sudden excessive exercise

Noncoronary causes of ST segment depression Glucose load Left ventricular hypertrophy Hyperventilation Mitral valve prolapse Interventricular conduction disturbance Preexitation syndrome Severe volume overload (aortic,mitral regurgitation) Supraventricular tacyarrhythmias

Adverse prognosis and multivessel CAD Duration of symptom-limiting < 6 METS Failure to increase SBP >120 mm hg , or a sustained decrease >10 mm hg , or below rest levels, during progressive exercise ST segment depression > 2mm , downsloping ST segment, starting at < 6 METS , involving > 5 leads, persisting > 5 min into recovery

Adverse prognosis and multivessel CAD Exercise–induced ST segment elevation (avr excluded) Angina pectoris at low exercise workloads Reproducible sustained (>30 sec) or symptomatic ventricular tacycardia

Exercise testing in determining prognosis

Symptomatic Patients TMT should be performed, before coronary Angiography -in patients with chronic CAD Excellent exercise tolerance ( > 10 Mets) usually have an excellent prognosis regardless of the anatomical extent of CAD

After Myocardial infarction TMT is useful to determine Risk stratification and assessment of prognosis functional capacity activity prescription after hospital discharge Assessment of adequacy of medical therapy

Cardiac Arrhythmias and conduction disturbances

Ventricular Premature Contraction Occurs frequently during exercise testing and increase with age not a useful marker of CAD in the absence of ischemic ST segment depression

In LBBB - Exercised induced ST segment depression is found in most patients - cannot be used as diagnostic of prognostic indicator In RBBB - Exercise induced ST depression in leads V1 - V4 is common finding and is non diagnostic of CAD

Supraventricular Arrhythmias Presence of SVT is not diagnostic for CAD

Pre-Excitation Syndrome Disappearance of delta waves occurs while exercise in 20 - 50 % of cases Abrupt disappearance – Good prognosis Presence of WPW syndrome, invalidates the use of ST segment analysis as a diagnostic method for detecting CAD

Special Clinical Applications Digitalis - Produce exertional ST depression Hypokalemia - associated with ST depression Antischemic therapy prolongs the time of onset of ST depression Increase exercise tolerance normalize exercise ECG response.(10 to 15 %) Heparin therapy increase total exercise duration

Special Clinical Applications In women Sensitivity and specificity are less in women than men False positive tests - due to greater release of catacholamines during exercise produce vasoconstriction more common during menses (or) preovulation

Special Clinical Applications Hypertension In normotensive asymptomatic individuals- increased long term risk is found in increased SBP > 214 mm HG increased SBP (or) DBP at 3rd minute of recovery Severe systemic hypertension cause exercise induced ST depression in the absence of atherosclerosis Exercise tolerance is decreased in patients with poor blood pressure control

Special Clinical Applications In elderly patients cardiac arrhythmias , chronotropic incompetence and hypertension responses are more common Diabetes Mellitus in patients with autonomic dysfunction and sensory neuropathy , anginal threshold may be increased

Special Clinical Applications After CABG indicate graft occlusion , stenosis or progression of CAD After PTCA In asymptomatic patients , 6 months post procedural test allows to diagnose restenosis

Indications for terminating exercise testing

CONTRAINDICATIONS ABSOLUTE RELATIVE

CONTRAINDICATIONS TO EXERCISE TESTING (ACC/AHA) ABSOLUTE Acute MI (within 2 d) USAP high risk Uncontrolled cardiac arrhythmias causing symptoms or hemodynamic compromise Symptomatic severe AS

CONTRAINDICATIONS TO EXERCISE TESTING (ACC/AHA )… ABSOLUTE … Uncontrolled symptomatic HF Acute pulmonary embolus or pulmonary infarction Acute myocarditis or pericarditis Acute aortic dissection

CONTRAINDICATIONS TO EXERCISE TESTING (ACC/AHA ) RELATIVE Left main coronary stenosis Moderate stenotic valvular heart disease Electrolyte abnormalities Severe arterial hypertension  200/110

CONTRAINDICATIONS TO EXERCISE TESTING (ACC/AHA )… RELATIVE … Tachyarrhythmias or bradyarrhythmias Hypertrophic cardiomyopathy and other forms of outflow tract obstruction Mental or physical impairment leading to an inability to exercise adequately High-degree AV block

TMT Report Exercise protocol used Duration of exercise Peak treadmill speed and grade Peak workload in MET or VO2 max Functional Capacity Maximum heart rate percentage of APMHR Resting and Peak Blood Pressure Symptoms Arrhythmias ECG Changes

Terms-Evalution of test results True positive(TP) = abnormal test results in individual with disease False positive(FP) = abnormal test results in individual without disease True negative(TN) = normal test result in individual without disease Likelihood ratio: odds of a test result being true of an abnormal test: sensitivity/(1-specifity) Of a normal test: specificity/(1-Sensitivity)

Terms-Evalution of test results Sensitivity: % of patients with CAD who have an abnormal result= TP/(TP+FN) Specificity: % of patients without CAD who have a normal results =TN/(TN+FP) Predictive value: % of patients with abnormal result who have CAD= TN/(TN+FN) Test accuracy: % of true test=(TP+TN)/total no. of tests performed Relative risk: Disease rate in persons with a positive test result/ Negative test result

Pretest probability of CAD Low Very low Intermediate Very low Intermediate Low High Intermediate 40-49 Men Women Very low Very low Low Very low Intermediate Very low Intermediate Intermediate 30-39 Men Women Asymptomatic Nonanginal Chest pain Atypical or Probable angina Typical or Definite angina Age/ Sex

Pretest probability of CAD Low Low Intermediate Intermediate Intermediate Intermediate High High 60-69 Men Women Low Very low Intermediate Low Intermediate Intermediate High Intermediate 50-59 Men Women Asymptomatic Nonanginal Chest pain Atypical or Probable angina Typical or Definite angina Age/ Sex

Duke Treadmill Score Exercise time - ( 5 x ST deviation ) - (4 x Treadmill angina index) used to identify prognostic , intermediate - high risk patients in whom coronary angiography would be indicated to define coronary anatomy Low-risk patients - scores of five or higher Intermediate risk -scores between five and –10 High risk -scores lower than -10

PROGNOSTIC SCORES DUKE treadmill score - by mark etal in Exercise time - (5 x max. ST depression) - 4 x 1987, based on 2842 patients. angina index. 5 YEARS SURVIVAL : > 5 - 97% - 10 to 4 - 91% < - 10 - 72% Score contains prognostic information even after clinical and cath data. Prognostic stratifing power greatest in 3 VD and lowest in SVD.

VETERENS AFFAIRS (VA) SCORE H/O CHF / digoxin Change in systolic BP. METS achieved. VA score = 5 x (CHF / digoxin) + ST depression + change in SBP - METS. < -2 low risk (annual mortality 1%) -2 to 2 moderate risk (annual mortality 7%) > 2 high risk (annual mortality 15%)

METABOLIC EQUIVALENT… 1 IV 2-3 III 4-6 II 6-10 I METS NYHA

Special applications After myocardial infarction/ unstable angina Cardiac rehabilitation Screening Exercise prescription Preoperation evaluation Dysrhythmias Intermittent claudication/Pulmonary disease

Asymptomatic Population Abnormal ECG Prevalance in Men - 5 to 12 % Prevalance in Women - 20 to 30 % Risk of development of cardiac events - 9 times more than normal Cardiac events over 5 years - 25 % Most common Cardiac event - Angina Prognostic value of an ST segment shift in women is less than in men

Ventricular Premature Contraction In CAD occurs in 20 % of patients In SCD survivors - 50 to 75 % More frequent during recovery phase Suppressed by B - Blocker therapy Exercise testing provokes repetitive VPC’s in patients with H/O sustained VT

Exercise stress ecg. dmo

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