Transcript Exercise stress electrocardiography

Exercise stress
electrocardiography
• Physiology and Protocol,
• Indications and Contraindications
• Frijo Jose A
Exercise physiology
• Sympathetic activation
• Parasympathetic withdrawal
• Vasoconstriction, exept– Exercising muscles
– Cerebral circulation
– Coronary circulation
• ↑norepinephrine and renin
Exercise physiology
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↑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 à ↑ O2 usage à
Person’s max. O2 consumption (VO2max)
reached
V02 peak
Oxygen
consumption
(liters/min)
Work rate (watts)
•The peak oxygen consumption is influenced by the age, sex, and
training level
of the
person performing
the exercise
V02 peak
(VO2max)
Oxygen
consumption
(liters/min)
•The plateau in peak oxygen consumption, reached during exercise
ratemaximal
involving a sufficiently large muscle mass, representsWork
the
(watts)
oxygen consumption
•Maximal oxygen consumption is limited by the ability to deliver O2 to
skeletal muscles and muscle oxidative capacity (mucle mass and
mitochondirial enzymes activity).
The ability to deliver O2 to muscles and
muscle’s oxidative capacity limit a
person’s VO2max. Training à ↑ 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
• the workload at which
rapid ventilation occures
is called the ventilatory
breakpoint (together
with lactate threshold)
Lactate acidifies the blood, driving off CO2 and increasing ventilatory
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 à
Glycolysis>aerobic metabolism à
↑ 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,
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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
Estimated Energy Requirements for Various Activities
Estimated Energy Requirements for Various Activities
Calculation of METs on the Treadmill
• METs = Speed x [0.1 + (Grade x 1.8)] + 3.5
3.5
• Calculated automatically by Device!
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•Note: Speed in meters/minute
conversion = MPH x 26.8
Grade expressed as a fraction
Treadmill protocol
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Bruce protocol
Naughton protocol
Weber protocol
ACIP(asymptomatic cardiac ischemia pilot)
Modified ACIP
The Bruce protocol
• Developed in 1949 by
Robert A. Bruce,
considered the “father of
exercise physiology”.
• Published as a
standardized protocol in
1963.
• Remains the gold-standard
for detection of myocardial
ischemia when risk
stratification is necessary.
Protocol description
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%
Calculation of METs on the Treadmill
• METs = Speed x [0.1 + (Grade x 1.8)] + 3.5
3.5
• Calculated automatically by Device!
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•Note: Speed in meters/minute
conversion = MPH x 26.8
Grade expressed as a fraction
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 inf lead q
– New Q in AVL
Contraindications to Exercise Testing
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Absolute
Acute MI (< 2 d)
High-risk unstable angina
Uncontrolled cardiac arrhythmias causing
symptoms or hemodynamic compromise
Symptomatic severe AS
Uncontrolled symptomatic CCF
Acute pulmonary embolus or pulmonary infarction
Acute myocarditis or pericarditis
Acute Ao dissection
Contraindications to Exercise Testing
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Relative
LMCA stenosis
Moderate stenotic valvular heart disease
Electrolyte abnormalities
Severe HTN
Tachyarrhythmias or bradyarrhythmias
HOCM and other forms of outflow tract obstruction
Mental or physical impairment leading to inability to
exercise adequately
• 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
Bayes' theorem
A theory of probability
‘The post test probability is proportional
to the pretest probability’
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
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
Pre-test Probability of CAD
by Age, Gender, and Symptoms
• Typical/Definite Angina Pectoris
• Age 30-39
– Men
– Women
Intermediate (10-90%)
Intermediate
• Age 40-49
– Men
– Women
High (>90%)
Intermediate
• Age 50-59
– Men
– Women
High
Intermediate
• Age 60-69
– Men
– Women
High
High
Pre-test Probability of CAD
by Age, Gender, and Symptoms
• Atypical/Possible Angina Pectoris:
• Age 30-39
– Men
– Women
Intermediate
Very Low (<5%)
• Age 40-49
– Men
– Women
Intermediate
Low (<10%)
• Age 50-50
– Men
– Women
Intermediate
Intermediate
• Age 60-69
– Men
– Women
Intermediate
Intermediate
Pre-test Probability of CAD
by Age, Gender, and Symptoms
•Nonanginal Chest Pain:
– Age 30-39
• Men
Low
• Women Very Low
– Age 40-49
• Men
Intermediate
• Women Very Low
– Age 50-59
• Men
Intermediate
• Women
Low
– Age 60-69
• Men
Intermediate
• Women
Intermediate
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Pre-test Probability of CAD
by Age, Gender, and Symptoms
• Asymptomatic:
– Age 30-39
• Men
Very Low
• Women Very Low
– Age 40-49
• Men
• Women
Low
Very Low
– Age 50-59
• Men
• Women
Low
Very Low
– Age 60-69
• Men
• Women
Low
Low
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.
EXERCISE TESTING 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 ↓.
•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
Exercise Testing in Asymptomatic Persons
Without Known CAD
• Class I
• None.
• 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.
•Submaximal protocols
• predetermined end point, often a 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)
• The incidence of fatal cardiac events(inclu
fatal MI & cardiac rupture)-- 0.03%
• Nonfatal MI and successfully resuscitated
cardiac arrest -- 0.09%
• Complex arrhythmias, including VT --1.4%.
• Symptom-limited protocols have an event rate
that is 1.9 times that of submaximal tests
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.
•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.
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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.
Clinical indications of high risk at pre-discharge
Strategy 3
Clinical indications of high risk at pre-discharge
Cardiac
cath
Exercise Testing Before and After Revascularization
• Class I
• 1. Demonstration of ischemia before revascularization.
• 2. Evaluating recurrent symps suggesting ischemia aft
revascularization.
• Class IIa
• Aft discharge for activity counseling and/or exercise training as
part of rehabilitation in pts aft 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
Sensitivity
Specificity
68%
77%
Nuclear
Imaging
87-92%
80-85%
Stress
Echo
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 exerciseinduced 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
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↓ 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
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 be
considered abnormal.
• ST 60 -- HR > 130/min
• ST 80 -- HR ≤ 130/min
Criteria for Abnormal and Borderline STSegment Depression on the Exercise ECG
• 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
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 ischemia----vasospasm, ↑coronary narrowing
•A 48-year-old man with several
atherosclerotic risk factors and a
normal rest ECG result developed
marked ST segment elevation (4 mm
[arrows]) in leads V2 and V3 with lesser
degrees of ST segment elevation in
leads V1 and V4 and J point
depression with upsloping ST
segments in lead II, associated with
angina.
•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
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>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
– Produces an abnormal ST-segment response to exercise. This abnormal ST
depression occurs in 25% to 40% of healthy subjects studied and is directly related to
age.
• Left Ventricular Hypertrophy
– Decreased specificity of exercise testing, but sensitivity is unaffected. Therefore, a
standard exercise test may still be the first test, with referrals for additional tests only
indicated in patients with an abnormal test result.
• Resting ST Depression
– Resting ST-segment depression has been identified as a marker for adverse cardiac
events in patients with and without known CAD.
• Left Bundle-Branch Block
– Exercise-induced ST depression usually occurs with left bundle-branch block and has
no association with ischemia. Even up to 1 cm of ST depression can occur in healthy
normal subjects. There is no level of ST-segment depression that confers diagnostic
significance in left bundle-branch block.
• Right Bundle-Branch Block
– The presence of right bundle-branch block does not appear to reduce the sensitivity,
specificity, or predictive value of the stress ECG for the diagnosis of ischemia.
• Beta Blocker Therapy
– For routine exercise testing, it appears unnecessary for physicians to accept the risk of
stopping beta-blockers before testing when a patient exhibits possible symptoms of
ischemia or has hypertension. However, exercise testing in patients taking betablockers may have 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.”
ACC/AHA Guidelines:
• “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 exe
•Inadequate ↑ of CO
•3VD,LMCA-d,cardiomyopathy,arrhythmias,
•
vasovagal,LVOTobs,hypovolemia,
•
prolonged vigorous exe
• Normal responses:
– Increase in SBP (> 20-30 mmHg)
– No change or fall in DBP
Maximum work capacity
• Important prognostic measurement
• Work performed in METs
• Not the no: of minutes of exercise
Exercise Capacity
• VO
max = (mph x 26.8) x (0.1 + [% grade X 1.8] + 3.5
2
•
1 MET (metabolic equivalent) = 3.5 ml 02 /kg/min
•
Stage 1 =
•
Stage 2 = 6 - 8 METS
•
Stage 3 = 8 -10 METS
5 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.**
• *Circ 1984;70:226.
• **Circ 1982;65:482.
Exercise Capacity
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;8:741748.
Heart rate response
•Inappropriate ↑ at low work load
•Anxiety (<1minute-transient)
•Persisting several minutes
•
AF,physically
deconditioned,hypovolemic,
•
anemic,marginal LV function
Heart rate response
• Chronotropic incompetence
• Inability to attain THR OR
• Abnormal HR Reserve(<80%)
• {%HR Reserve=(HRpeak-HRrest)/(220-ageHRrest)}
• Autonomic dysfunction,SN dysfuntion,
• drugs,myocardial ischemia
• ↑long term mortality (not on β blockers)
Chronotropic Incompetence
Circ 1996;93:1520.
Framingham Heart
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.
Heart Rate Recovery
• Abnormal:
•
•
TMT (upright)
•
TMT (supine)
1 minute
< 12 bpm
< 18 bpm
• An upright value <22 bpm at 2 minutes is abnormal
• Poor prognosis independent of other factors
•
Heart Rate Recovery After Exercise Testing
Predicts Outcome in CAD
Exercise induced Chest discomfort
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Usually after ischemic ST changes
May be associated with 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
•
•(+) Stress Test with angina
Mortality
5%/yr.
•(+) Stress Test, no angina
2.5%/yr.
Circ 1984;70:547551.
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
• Symptom limiting exercise < 5METs
• Abnormal BP response
• ST↓≥2mm or downsloping ST↓
• <5METs, ≥5 leads, persisting ≥5 mins into
reco
• ST↑
• Angina at low exercise work loads
• Reproducible sustained/symptomatic VT
Indications for Terminating Exercise Testing
• Absolute indications
• Drop in systolic BP >10 mm Hg from baseline when
accompanied by other evidence of ischemia
• Moderate to severe angina
• ↑ CNS sympts (ataxia, dizziness, or near-syncope)
• Signs of poor perfusion (cyanosis or pallor)
• Technical difficulties in monitoring ECG or systolic BP
• Subject’s desire to stop
• Sustained VT
• ST ↑ (≥1.0 mm) in leads without Q-waves (other than
V1 or aVR)
Indications for Terminating Exercise Testing
• Relative indications
• ↓ 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
• Arrhythmias other than sustained VT, including multifocal
PVCs, triplets of PVCs, SVT, heart block, or
bradyarrhythmias
• Fatigue, shortness of breath, wheezing, leg cramps, or
claudication
• Development of BBB or IVCD that cannot be
distinguished from VT
• Increasing chest pain
• Hypertensive response
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