Stress Testing: Choosing the Right Test for your Patients

1. Stress Testing: Choosing the Right Test for your Patients Sanford J. Gips, M.D., FACC Cardiovascular Associates of the Delaware Valley

2. Choosing the Best Test • What is the patient's pretest risk of CHD? • Exercise vs. Pharmacologic • Imaging vs Exercise ECG only • How accurate are the alternative tests? • Do special considerations make one test more suitable in a specific patient?

3. Exercise ECG Testing vs. Pharmacologic • Exercise documents workload that induces ischemia • Exercise Capacity and Hemodynamic Response predict prognosis independent of ischemia on imaging • Limited by resting ST changes, LVH, LBBB, paced rhythm, WPW

4. EKG Criteria in Stress Testing

5. Non-invasive Testing Modalities • Echocardiography • Radionuclide Myocardial Perfusion Imaging (Thallium, Cardiolyte, Myoview) • Positron Emission Tomo (PET) • CT Angiography

6. Stress Echo Baseline

7. Stress Echo After Exercise

8. Radionuclide Imaging

10. Stress Echo vs. Radionuclide Perfusion • Echo • Higher specificity • More extensive evaluation of anatomy and function • Greater convenience, availability • Lower cost • Stress Perfusion • Higher technical success rate • Higher sensitivity-esp circ disease • Better accuracy when multiple resting wall motion abnormalities present • More extensive published data for gauging prognosis

11. Questions to consider when ordering a stress test • Pre-test probability of CAD • Reason for ordering stress test • Suspected CAD • Known CAD to evaluate new symptoms • Known CAD to eval med rx • Advantages and limitations of different stress testing modalities

13. Why is Pre-test Probability Important • Low pre-test probability (5%) • PPV of +EST only 21% • High pre-test probability (90%) • PPV of +EST 98%, -EST still 83% chance of CAD • Intermed pre-test probab (50%) • PPV of +EST 83, -EST decreases likelihood to 36%

14. Orders on Chest Pain Pts • Suspected CAD (r/o CAD/angina) • Don’t order meds that will inhibit ability to obtain adequate stress test (B-blockers, non-DHP Ca++) • Don’t order meds with high toxic/therapeutic ratios for low risk pts (Nitrates) • Do order anti-hypertensive meds (DHP Ca++, ACE-I, diuretics) • Do order anti-platelet rx, anti-coag

15. Stress Testing in the Setting of Known CAD • Purpose in this case is assessing adequacy of medical rx • Continue cardiac meds • Getting HR to >85% not always necessary

16. Which Stress Test to Order?

17. Which Stress Test to Order? • Exercise EKG is always preferable if pt can exercise to >85% MPHR • Pharmacologic if unable to exercise to full capacity, LBBB, abnl ST, LVH, WPW • Dipyridimole or adenosine for most pharmacologic stress • Dobutamine only for active wheezing or known prob with persantine

18. Which imaging modality • To some degree it is your choice • Nuc better if likely to have poor echo windows or abnl baseline LV function • Echo better if time or radiation are important considerations • PET best for obese, most sensitive

19. Markers of LM or 3-Vessel CAD • Hypotension • Bradycardia • Transient ischemic dilatation (TID) • Multiple wall motion abnorm or cavity dilatation on echo • Ventricular Tachycardia

22. Who do I send right to cath? • High pre-test probability and classic symptoms • Previously unknown abnormal LV function • Recurrent CP with recent negative or equiv stress test

23. Take Home Messages • Most hospitalized pts will receive imaging stress testing • Exercise EKG is preferable to pharmacologic stress unless pt can’t achieve target HR or has LBBB/pacer • Avoid negchronotropes if stress test is to r/o CAD

24. Take Home Messages • Nitroglycerin is the most overused, toxic med in the hospital • Discharge for elective stress testing may be appropriate for low risk patients • Catheterization is more cost-effective for high-risk patients or recurrent chest pain despite negative studies