This document discusses options for stress testing in patients with stable ischemic heart disease, including treadmill exercise testing (ETT), dobutamine stress echocardiography (DST), and myocardial perfusion imaging (MPI) with thallium or SPECT. ETT is preferred for most patients who can exercise and have a normal baseline ECG. DST and MPI are alternatives for those with intermediate pretest probability or non-diagnostic ETT. Each test has advantages and limitations regarding sensitivity, specificity, cost, radiation exposure, and ability to evaluate ventricular function, ischemia, and viability. Information from stress tests provides important prognostic indicators to guide clinical decisions.

1. INVESTIGATING STABLE IHD –
TREADMILL, DOBUTAMINE STRESS
ECHO OR STRESS THALLIUM??
Dr Robin Pinto
Holy Family Hospital,
Glenmark Cardiac Centre

2. FACTORS DECIDING CHOICE
• Ability to exercise
• Baseline ECG abnormalities
• Prior CABGS / PTCA / MI
• Portability
• Cost
• Radiation
• Physician Preference
• Sensitivity And Specificity

3. PROBABILITY OF CAD

4. VERIFICATION BIAS
• Describes the impact of reporting sensitivity
and specificity when calculated primarily using
patients with positive stress test results
• Sensitivity = TP / TP + FN
• Specificity = TN / TN + FP

5. VERIFICATION BIAS

6. ROLE OF ETT AS A DIAGNOSTIC TEST
TEST OF CHOICE IN THOSE WITH
WITH INTERMEDIATE TEST PROBABILITY
NORMAL BASLINE ECG
ABLE TO EXERCISE
NO PRIOR REVASCULARISATION

7. INCREASING SENSITIVITY OF ETT
EXISTING:
1. ST deviation and slope
2. ST / HR slope > 2.4 µV / bpm
3. ST / HR index > 1.6 µV / bpm
NEW:
1. ST / HR Hysteresis – integrates difference in
ST segment depression between exercise and
3 min of recovery .
2. Chronotropic incompetence

8. DST - ADVANTAGES
• Totally non invasive, safe , repeatable
• No radiation
• Relatively short procedure time
• Simple instrumentation, portable
• Can identify other structural abnormalities

9. Disadvantages of DST
• Images difficult to acquire because of marked
cardiac excursion
• RWMA may be transient
• Highly operator dependent
• Inability to image all segments in 15%
• Detection of residual ischemia in infarct zone
difficult

10. WHATS NEW IN DST
• Use of LV opacification
• MCI - microvascular perfusion, viability,
improving sensitivity of DST
• Use of Speckle tracking / Strain imaging

12. • 32 yr/ M,
• IGT,
• Non smoker,
• Atypical chest pain
• Intermediate pretest probability

15. 49 yr old marathon runner, CT Calcium Score = 1095.03

19. Microvascular re-perfusion Acute MI

21. No microvascular reflow

22. MPI – Myocardial Perfusion Imaging
• Can evaluate Ventricular function
• Most sensitive for diagnosis of CAD
• Identifies region of ischemia
• Can assess myocardial viability

24. DISADV OF MPI
• Attenuation artifacts
• In severe disease, balanced ischemia can lead
to a false negative test

25. PROGNOSTIC INDICATORS FROM ETT
• Duration of exercise < 6 METS
• Failure to increase syst BP > 120 mm Hg,
sustained decrease > 10 mm hg below rest
• ST depression > 2.0 mms
• Exercise induced ST elevation
• Angina at low workloads
• Sustained (> 30 secs) / symptomatic VT

27. NEWER PROGNOSTIC INDICATORS
FROM ETT
MORTALITY
• Functional Capacity (METS, DTS)
• Heart Rate Recovery - < 12 bpm in first min
• Chronotropic Incompetence < 80% THR
SUDDEN CARDIAC DEATH (SCD)
TWA (T-wave alternans) > 65 µV is high risk
Frequent PVCs in recovery > 7 / min

28. ADVERSE PROGNOSTIC MARKERS IN
DST & MPI
• Amt of myocardium - > 3 segments in DST, > 10%
myocardium in jeopardy
• More than one territory
• LV dysfunction – LV dilatation on DST, Fall in EF by
> 5%, Global EF < 45% , Transient ischemic
dilatation ratio > 1.2, Lung uptake, RV uptake /
dilatation

30. CONCLUSION
• Performing these tests routinely in the general
population is probably not indicated
• ETT – Test of choice for the majority of patients
with a baseline normal ECG and the ability to
walk on the treadmill
• DST / MPI – Those with a non diagnostic ETT and
intermediate test probability.

31. CONCLUSION
• DST – Increasing use, especially useful in those
with LBBB / bronchoconstriction
• MPI – especially to assess residual ischemia in
infarct territory, assess viability, post CABGS,
assess significance of non critical lesions
• Prognostic information gleaned from each of
these tests extremely important in making clinical
decisions