Exercise ECG - cardiologycmc.in

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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 
Person’s max. O2 consumption (VO2max) reached
V02 peak
Oxygen
consumption
(liters/min)
Work rate (watts)

The slope of the
o2–work 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 muscle’s
oxidative capacity limit a person’s VO2max. Training 
↑ VO2max
V02 peak
(trained)
70% V02 max (trained)
V02 peak
(untrained)
Oxygen
consumption
(liters/min)
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
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
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 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, 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
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 ≥10mm 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%
80-85%
88-95%
INVESTIGATION OF HEART RHYTHM DISORDERS
Class I
•
1. Identification of appropriate settings in pts with rateadaptive 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 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 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 STSEGMENT 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 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 ↑ ≥0.10mV(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
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 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
VO2 max = (mph x 26.8) x (0.1 + [% grade X 1.8] + 3.5
1 MET (metabolic equivalent) = 3.5 ml 02 /kg/min
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. (JACC 1986;8:741 748)
*Circ 1984;70:226.
**Circ 1982;65:482.
HEART RATE RESPONSE
Inappropriate ↑ at low work load

Anxiety (<1minute-transient)

Persisting several minutes
AF
Physically deconditioned
Hypovolemia
Anemia
Marginal LV function
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 & MULTIVESSEL CAD
1.
Symptom limiting exercise < 5METs
2.
Abnormal BP response
3.
ST↓≥2mm 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.
Subject’s 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
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