Презентация на тему «How to Perform and Interpret an Exercise Test»

How to Perform and Interpret an Exercise Test

V. Froelicher, MD Professor of Medicine Stanford University VA Palo Alto HCS

Key Points of Exercise Testing

Manual SBP measurement (not automated) most important for safety Adjust to clinical history (couch potatoes) No Age predicted Heart Rate Targets The BORG Scale of Perceived Exertion METs not Minutes Fit protocol to patient (RAMP) Avoid HV and cool down walk Use standard ECG analysis/ 3 minute recovery/ use scores Heart rate recovery Expired Gas Analysis?

BORG SCALE

Very, very light

Very light

Fairly light

Somewhat hard

Hard

Very hard

Very, very hard

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Symptom-Sign Limited Testing Endpoints – When to stop

Dyspnea, fatigue, chest pain Systolic blood pressure drop ECG--ST changes, arrhythmias Physician Assessment Borg Scale (17 or greater)

How to read an Exercise ECG

Good skin prep PR isoelectric line Not one beat Three consistent complexes Averages can help Garbage in, garbage out Three minute recovery

Types of Exercise

Isometric (Static) weight-lifting pressure work for heart, limited cardiac output, proportional to effort Isotonic (Dynamic) walking, running, swimming, cycling Flow work for heart, proportional to external work Mixed

There are Two Types to Consider: Myocardial (MO2) Internal, Cardiac

Ventilatory (VO2) External, Total Body

Oxygen Consumption During Dynamic Exercise Testing

Myocardial (MO2)

Coronary Flow x Coronary a - VO2 difference Wall Tension (Pressure x Volume, Contractility, Stroke Work, HR) Systolic Blood Pressure x HR Angina and ST Depression usually occurs at same Double Product in an individual ** Direct relationship to VO2 is altered by beta-blockers, training,...

Problems with Age-Predicted Maximal Heart Rate

Which Regression Formula? (2YY - .Y x Age) Big scatter around the regression line poor correlation [-0.4 to -0.6] One SD is plus/minus 12 bpm Confounded by Beta Blockers A percent value target will be maximal for some and sub-max for others Borg scale is better for evaluating Effort Do Not Use Target Heart Rate to Terminate the Test or as the Only Indicator of Effort or adequacy of test

Myocardial (MO2)

Systolic Blood Pressure x HR SBP should rise > 40 mmHg Drops are ominous (Exertional Hypotension) Diastolic BP should decline

Ventilatory (VO2)

Cardiac Output x a-VO2 Difference VE x (% Inspired Air Oxygen Content - Expired Air Oxygen Content) External Work Performed ****Direct relationship with Myocardial O2 demand and Work is altered by beta-blockers, training,...

VO2 THE FICK EQUATION VO2 = C.O. x C(a-v)O2 C(a-v)O2 ~ k then, VO2 ~ C

O.

What is a MET

Metabolic Equivalent Term 1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5 ml O2 /Kg/min Actually differs with thyroid status, post exercise, obesity, disease states But by convention just divide ml O2/Kg/min by 3.5

Key MET Values (part 1)

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; limit immediate post MI; cost of basic activities of daily living

Key MET Values (part 2)

10 METs = As good a prognosis with medical therapy as CABS 13 METs = Excellent prognosis, regardless of other exercise responses 16 METs = Aerobic master athlete 20 METs = Aerobic athlete

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

METs---not Minutes (Report Exercise Capacity in METs)

Can compare results from any mode or Testing Protocol Can Optimize Test by Individualizing for Patient Can adjust test to 8-10 minute duration (aerobic capacity--not endurance) Can use prognostic power of METs

Estimated vs Measured METs

All Clinical Applications based on Estimated Estimated Affected by: Habituation (Serial Testing) Holding on Deconditioning and Disease State Measured Requires a Mouthpiece and Delicate Equipment Measured More Accurate and Permits measurement of Gas Exchange Anaerobic Threshold and Other Mxments (VE/VCO2) Prognostic in CHF and Transplantation

WORK TREADMILL

RAMP

WORK

WORK

TIME

TIME

Why Ramp

Started with Research for AT and ST/HR but clinicaly helpful Individualized test Using Prior Test, history or Questionnaire Linear increase in heart rate Improved prediction of METs Nine-minute duration for most patients Requires special Treadmill controller or manual control by operator

Should Heart Rate Drop in Recovery be added to ET

Long known as a indicator of fitness: perhaps better for assessing physical activity than METs Recently found to be a predictor of prognosis after clinical treadmill testing Does not predict angiographic CAD Studies to date have used all-cause mortality and failed to censor

Heart Rate Drop in Recovery

Probably not more predictive than Duke Treadmill Score or METs Studies including censoring and CV mortality needed Should be calculated along with Scores as part of all treadmill tests

Heart Rate Drop in Recovery vs METs

10 to 15% increase in survival per MET Can be increased by 25% by a training program What about Heart Rate Recovery???

Maximal Heart Rate vs METs

Diagnosis vs Prognosis

Diagnosis CAD Prognosis with symptoms/CAD After MI Using Ventilatory

Gas Analysis Special Groups

AHA/ACC Exercise Testing Guidelines: Recommendations for Exercise Testing

AHA/ACC Exercise Testing Guidelines: Recommendations for Exercise

Testing

Special Groups: Pre- and Post-Revascularization Women Asymptomatic Pre-surgery Valvular Heart Disease Cardiac Rhythm Disorders

The ACC/AHA Guidelines for the Diagnostic Use of the Standard Exercise

Test

Class I (Definitely appropriate) - Adult males or females (including RBBB or < 1mm resting ST depression) with an intermediate pre-test probability of coronary artery disease based on gender, age and symptoms (specific exceptions are noted under Class II and III below). Class IIa (Probably appropriate) - Patients with vasospastic angina.

Pre Test Probability of Coronary Disease by Symptoms, Gender and Age

Diagnostic Use, continued:

Class IIb (Maybe appropriate) – Patients taking Digoxin with less than 1 mm resting ST depression. Patients with ECG criteria for left ventricular hypertrophy with less than 1 mm ST depression. Patients with a high pre-test probability of coronary artery disease by age, symptoms and gender. Patients with a low pre-test probability of CAD by age, symptoms and gender.

Diagnostic Use, continued:

Class III (Not appropriate) - 1. To use the ST segment response in the diagnosis of coronary artery disease in patients who demonstrate the following baseline ECG abnormalities: pre-excitation (WPW) syndrome; electronically paced ventricular rhythm; more than one millimeter of resting ST depression; LBBB 2. To use the ST segment response in the diagnosis of coronary artery disease in MI patients

Comparison of Tests for Diagnosis of CAD

Males

Choose only one per group

Variable

Circle response

Sum

<40=low prob 40-60= intermediate probability >60=high probability

Maximal Heart Rate

Exercise ST Depression

Age

Angina History

Hypercholesterolemia?

Diabetes?

Exercise test

induced Angina

Total Score:

Less than 100 bpm = 30

100 to 129 bpm = 24

130 to 159 bpm =18

160 to 189 bpm =12

190 to 220 bpm =6

1-2mm =15

> 2mm =25

>55 yrs =20

40 to 55 yrs = 12

Definite/Typical = 5

Probable/atypical =3

Non-cardiac pain =1

Yes=5

Yes=5

Occurred =3

Reason for stopping =5

Women

Choose only one per group

<37=low prob 37-57= intermediate probability >57=high probability

Indications for Exercise Testing to Assess Risk and prognosis in

patients with symptoms or a prior history of coronary artery disease: Class I. Should be used: Patients undergoing initial evaluation with suspected or known CAD. Specific exceptions are noted below in Class IIb. Patients with suspected or known CAD previously evaluated with significant change in clinical status.

The ACC/AHA Guidelines for the Prognostic Use of the Standard Exercise Test

Prognostic Use, continued:

Class IIb. Maybe Appropriate for: Patients who demonstrate the following ECG abnormalities: Pre-excitation (WPW) syndrome; Electronically paced ventricular rhythm; More than one millimeter of resting ST depression; and LBBB. Patients with a stable clinical course who undergo periodic monitoring to guide management

Prognostic Use, continued:

Class IIa. Probably Appropriate: None Class III. Should not be used for prognostication: Patients with severe comorbidity likely to limit life and/or consideration for revascularization procedures

Endpoints for Prediction of Prognosis

Why is this even an issue?? Confusion All-cause certainly best for interventional studies CV mortality more appropriate outcome for CV tests

DUKE Treadmill Score for Stable CAD

METs - 5 X [mm E-I ST Depression] - 4 X [Treadmill Angina Index] ******Nomogram*******

E-I = Exercise Induced

Duke Treadmill Score (uneven lines, elderly

“All-comers” prognostic score

SCORE = (1=yes, 0=no) METs<5 + Age>65 + History of CHF + History of MI or Q wave a=0, b=1, c=2, d=more than 2

But Can Physicians do as well as the Scores

954 patients - clinical/TMT reports Sent to 44 expert cardiologists, 40 cardiologists and 30 internists Scores did better than all three but was most similar to the experts

Key Points of Exercise Testing

Manual SBP measurement (not automated) most important for safety Adjust to clinical history (couch potatoes) No Age predicted Heart Rate Targets The BORG Scale of Perceived Exertion METs not Minutes Fit protocol to patient (RAMP) Avoid HV and cool down walk Use standard ECG analysis/ 3 minute recovery/ use scores Heart rate recovery Expired Gas Analysis?

Question 1

What is the most important prognostic measurement from the exercise test? 1. BORG scale estimate 2. ST depression 3. Exercise time 4. Exercise capacity

Question 2

What is the most appropriate indicator of a maximal effort? 1. BORG scale 2. ST depression 3. Heart rate 4. Exercise capacity

All references are available as pdf files on www

cardiology.org along with scores and sample report generator

Thank you