Stress Testing

UTSW House Staff Didactic SeriesAnand Rohatgi, MD, MSCS, FACC, FAHA

Assistant Professor

Division of Cardiology

Stress Tests

Stress modality “Detection” modality

Treadmill exercise*

Vasodilator

Adenosine

Regadenson

Dobutamine

EKG (ETT)

Myocardial perfusion

Echo (stress echo)

Probability

Gibons at al, Progr Cardiol 1983;12:67

Positive Predictive

Value

Probability of a subject

with a positive test,

actually having disease

Depends uponSensitivity

Specificity

Population prevalence

or pretest likelihood

Pretest Probability

Age Gender Typical

Angina

Atypical

Angina

Nonanginal

CP

Asymptoma

tic

30-39 Men Intermediate Intermediate Low Very Low

40-49 High Intermediate Intermediate Low

50-59 High Intermediate Intermediate Low

60-69 High Intermediate Intermediate Low

30-39 Women Intermediate Very Low Very Low Very Low

40-49 Intermediate Low Very Low Very Low

50-59 Intermediate Intermediate Low Very Low

60-69 High Intermediate Intermediate Low

Diamond et al, NEJM 1979;300:1350

ACC/AHA 2002 ETT Indication

Class I (Indicated)

• Intermediate prob

CAD

• including RBBB,

<1mm resting ST

depression

Class III (Not indicated)

• Pre-excitation

• V-paced

• >1mm resting ST dep

• LBBB

• Diagnosis for pt w/

established CAD

MI or death 1 per 2500

Contraindications to ETT

• Acute myocardial infarction (<2 days)

• Unstable angina with recent rest pain

• Untreated life-threatening cardiac arrhythmias

• Advanced atrioventricular block

• Acute myocarditis or pericarditis

• Critical aortic stenosis or severe IHSS

• Uncontrolled hypertension

• Acute systemic illness (PE, dissection, anemia, thyroid, fever, etc.)

Exercise Treadmill Testing- Protocols

Standard Bruce Protocol

Stage Min MPH Grade METS

I 03:00 1.7 10% 5

II 03:00 2.5 12% 7

III 03:00 3.4 14% 10

IV 03:00 4.2 16% 13.5

V 03:00 5.0 18% 16+

*3 minute stages

Variations

Modified Bruce Protocol

2 warm-up stages

Naughton Protocol

fixed speed

Submaximal ETT

Not to exceed 5 METS

Not to exceed 70%

MPHR

Diagnosis of Ischemia

Positive test

– 1mm horizontal or down sloping ST segment depression 0.06-0.08msec after the j-point

(5% w/ CAD meet criteria in recovery alone)

– Lateral leads (V4-V6)

Up sloping

Horizontal

Down sloping

Adequate stress: 85% max predicted HR (220-age)

Decreased Specificity

• LVH with repolarization abnormalities

– Decreased specificity with no change in sensitivity

• Resting ST depression > 1mm

• LBBB

• RBBB (diagnostic accuracy preserved in V5, V6, II, AVF

• Digoxin

– ST depression in 25-40% of healthy subjects

– 2 weeks required washout

Non-coronary Causes of ST

segment depression

• Severe aortic stenosis

• Severe hypertension

• Cardiomyopathy

• Anemia

• Hypokalemia

• Severe hypoxia

• Digitalis use

• Sudden excessive

exercise

• Glucose load

• Left ventricular hypertrophy

• Hyperventilation

• Mitral valve prolapse

• Intraventricular conduction defect

• Preexcitation syndrome

• Severe volume overload

• Supraventricular tachyarrhythmias

Thompson CA, et al. JACC 2000; 36:2140-5. Lauer MS, et al. Circulation 1996;93:1520-6

Prognostic Markers

• Maximal exercise capacity

• Chronotropic incompetence

• HR recovery

• Risk scores

Exercise Capacity

MET= 02 uptake of 70kg

man at rest for 1 min

=3.5ml O2/kg/min

Exercise capacity is

one of the strongest

prognostic markers

Encompasses many

different factors

Each 1 MET increase =

12% increased

survival

Myers et al, NEJM 2002;346:793

Stanford database of 6000 men

Ref

<10 <8

>13 >11

ETT in asymptomatic pts

Class I

• None.

Class IIa

• Evaluation of asymptomatic persons with diabetes mellitus who plan to start vigorous exercise (see page 39). (Level of Evidence: C)

Class IIb

• Evaluation of persons with multiple risk factors as a guide to risk-reduction therapy.*

• Evaluation of asymptomatic men older than 45 years and women older than 55 years:

– Who plan to start vigorous exercise (especially if sedentary) or

– Who are involved in occupations in which impairment might impact public safety or

– Who are at high risk for CAD due to other diseases (e.g., peripheral vascular disease and chronic renal failure)

Class III

• Routine screening of asymptomatic men or women.

Myocardial Perfusion Imaging

Stress modality “Detection” modality

Treadmill exercise*

Vasodilator

Adenosine

Regadenson

Dobutamine

Myocardial perfusion

(Nuclear)

Myocardial Perfusion Imaging

Schinkel AF, Bax JJ, Geleijnse ML, et al. Eur Heart J 2003;24:789-800.

Myocardial Perfusion Testing

Rest

Maximal coronary

vasodilitation

No coronary flow

reserve

Stress

Heterogeneous

Perfusion

Vasodilators

• Dipyridamole– Increases adenosine levels

– 50% with side effects, last 15-25 minutes

• Adenosine– Coronary vasodilation via A2A receptor

– 140mcg/kg/min x 6min

– 80% with side effects: flushing 40%, AV block (7.6%), hypotension (5%), <10sec ½ life

– CP non-specific

– 1mmST depression 5-7%>CAD

• Regadenoson– A2A agonist with lower affinity for receptors >

side effects

– Side effets of SOB, headache, flushing, last 15-30 min

– Single 5ml injection

Contra-indications

• AV block (2nd or 3rd)

•Bronchospasm

•Methyl xanthines

•ACS

Myocardial Perfusion Testing

(Nuclear: SPECT)

Protocol (Dual Isotope)

• Resting images after Thallium-201

injection

• Stress, with Technetium-99 injected at

peak exercise (Cardiolite/Myoview)

• Post-stress images (with gated SPECT)

Hachamovitch R, Hayes SW, Friedman JD, Cohen I, Berman DS. Circulation 2003;107:2900-6

→ Revasc better

Stress Tests

Stress modality “Imaging” modality

Treadmill exercise*

Vasodilator

Adenosine

Regadenson

Dobutamine Echo (stress echo)

Stress Echo

Schinkel AF, Bax JJ, Geleijnse ML, et al. Eur Heart J 2003;24:789-800.

Abnormal

flow reserve

Ischemia

Stress Echocardiography

• Stress echo is used to

assess ischemia

• Wall motion

abnormalities are the

earliest response to

ischemia19

30

39

0 50

Wall

Motion

EKG

change

Chest

Pain

Seconds

Hauser et al. JACC 1985;5:193

Post-balloon inflation

Dobutamine Echo

Mechanisms of Action

– β1 agonist– inotropy and

chronotropy (some

vasodilatation)

– induces ischemia at lower

RPP than ETT, (RPP

approximately 16-20K)

– Begin at 10mcg/kg/min,

increasing to 40 mcg/kgmin

Side Effects

– 3:1000 serious side effects

• MI

• Ventricular fibrillation

– Atrial / Ventricular

arrhythmia

– Hypertension

– Hypotension (cavity

obliteration)

– Headache / Tremor

Comparing SECHO and MPI

Advantages Disadvantages

MPI (Nuclear)

Detects abnl flow reserve

Peak-exercise images

acquired

Most studies complete

Quantified LVEF and

volumes

Longer time than secho

Radiation

Lower spatial resolution

Inferior wall diff to eval

Balanced ischemia missed

SECHO

Safe

No radiation

Portable, faster

Structural information

Peak-exercise images

difficult to acquire

False-neg w/ rapid recovery

Ischemic response needed

15% cannot assess entire

myocardium

Afib, LBBB

ETT

EKG not

interpretable

Stress

Echo

Stress

MPI

Poor echo

arrhythmia

Asthma

COPD

AV Block

Dobutamine

Echo

LBBB

V-paced

arrhythmia

Poor echo

Adenosine

MPI

Unable

to walk

Poor echo

Dobutamine

MPI