Stress Testing: Choosing Stress Testing: Choosing the Right Test for your the Right Test for your PatientsPatients

Sanford J. Gips, M.D., FACCSanford J. Gips, M.D., FACCCardiovascular Associates of the Cardiovascular Associates of the Delaware ValleyDelaware Valley

Choosing the Best TestChoosing the Best Test

• What is the patient's pretest risk of What is the patient's pretest risk of CHD?CHD?

• Exercise vs. PharmacologicExercise vs. Pharmacologic

• Imaging vs Exercise ECG onlyImaging vs Exercise ECG only

• How accurate are the alternative tests?How accurate are the alternative tests?

• Do special considerations make one Do special considerations make one test more suitable in a specific test more suitable in a specific patient?patient?

Exercise ECG Testing vs. Exercise ECG Testing vs. PharmacologicPharmacologic

• Exercise documents workload Exercise documents workload that induces ischemiathat induces ischemia

• Exercise Capacity and Exercise Capacity and Hemodynamic Response predict Hemodynamic Response predict prognosis independent of prognosis independent of ischemia on imagingischemia on imaging

• Limited by resting ST changes, Limited by resting ST changes, LVH, LBBB, paced rhythm, WPWLVH, LBBB, paced rhythm, WPW

EKG Criteria in Stress EKG Criteria in Stress TestingTesting

Non-invasive Testing Non-invasive Testing ModalitiesModalities

• EchocardiographyEchocardiography

• Radionuclide Myocardial Radionuclide Myocardial Perfusion Imaging (Thallium, Perfusion Imaging (Thallium, Cardiolyte, Myoview)Cardiolyte, Myoview)

• Positron Emission Tomo (PET)Positron Emission Tomo (PET)

• CT AngiographyCT Angiography

Stress Echo BaselineStress Echo Baseline

Stress Echo After ExerciseStress Echo After Exercise

Radionuclide ImagingRadionuclide Imaging

Stress Echo vs. Stress Echo vs. Radionuclide PerfusionRadionuclide Perfusion• EchoEcho

– Higher specificityHigher specificity– More extensive evaluation of anatomy and functionMore extensive evaluation of anatomy and function– Greater convenience, availabilityGreater convenience, availability– Lower costLower cost

• Stress PerfusionStress Perfusion– Higher technical success rateHigher technical success rate– Higher sensitivity-esp circ diseaseHigher sensitivity-esp circ disease– Better accuracy when multiple resting wall motion Better accuracy when multiple resting wall motion

abnormalities presentabnormalities present– More extensive published data for gauging prognosisMore extensive published data for gauging prognosis

Questions to consider when Questions to consider when ordering a stress testordering a stress test

• Pre-test probability of CADPre-test probability of CAD• Reason for ordering stress testReason for ordering stress test– Suspected CADSuspected CAD– Known CAD to evaluate new Known CAD to evaluate new

symptomssymptoms– Known CAD to eval med rxKnown CAD to eval med rx

• Advantages and limitations of Advantages and limitations of different stress testing modalitiesdifferent stress testing modalities

Why is Pre-test Probability Why is Pre-test Probability ImportantImportant

• Low pre-test probability (5%)Low pre-test probability (5%)– PPV of +EST only 21%PPV of +EST only 21%

• High pre-test probability (90%)High pre-test probability (90%)– PPV of +EST 98%, -EST still 83% PPV of +EST 98%, -EST still 83%

chance of CADchance of CAD

• Intermed pre-test probab (50%)Intermed pre-test probab (50%)– PPV of +EST 83, -EST decreases PPV of +EST 83, -EST decreases

likelihood to 36%likelihood to 36%

Orders on Chest Pain PtsOrders on Chest Pain Pts

• Suspected CAD (r/o CAD/angina)Suspected CAD (r/o CAD/angina)– Don’t order meds that will inhibit ability to Don’t order meds that will inhibit ability to

obtain adequate stress test (B-blockers, obtain adequate stress test (B-blockers, non-DHP Ca++)non-DHP Ca++)

– Don’t order meds with high Don’t order meds with high toxic/therapeutic ratios for low risk pts toxic/therapeutic ratios for low risk pts (Nitrates)(Nitrates)

– Do order anti-hypertensive meds (DHP Do order anti-hypertensive meds (DHP Ca++, ACE-I, diuretics)Ca++, ACE-I, diuretics)

– Do order anti-platelet rx, anti-coagDo order anti-platelet rx, anti-coag

Stress Testing in the Stress Testing in the Setting of Known CADSetting of Known CAD

• Purpose in this case is assessing Purpose in this case is assessing adequacy of medical rxadequacy of medical rx

• Continue cardiac medsContinue cardiac meds

• Getting HR to >85% not always Getting HR to >85% not always necessarynecessary

Which Stress Test to Which Stress Test to Order?Order?

Which Stress Test to Which Stress Test to Order?Order?

• Exercise EKG is always preferable if Exercise EKG is always preferable if pt can exercise to >85% MPHRpt can exercise to >85% MPHR

• Pharmacologic if unable to exercise Pharmacologic if unable to exercise to full capacity, LBBB, abnl ST, LVH, to full capacity, LBBB, abnl ST, LVH, WPWWPW

• Dipyridimole or adenosine for most Dipyridimole or adenosine for most pharmacologic stresspharmacologic stress

• Dobutamine only for active wheezing Dobutamine only for active wheezing or known prob with persantineor known prob with persantine

Which imaging modalityWhich imaging modality

• To some degree it is your choiceTo some degree it is your choice• Nuc better if likely to have poor Nuc better if likely to have poor

echo windows or abnl baseline LV echo windows or abnl baseline LV functionfunction

• Echo better if time or radiation are Echo better if time or radiation are important considerationsimportant considerations

• PET best for obese, most PET best for obese, most sensitivesensitive

Markers of LM or 3-Vessel Markers of LM or 3-Vessel CADCAD

• HypotensionHypotension

• BradycardiaBradycardia

• Transient ischemic dilatation Transient ischemic dilatation (TID)(TID)

• Multiple wall motion abnorm or Multiple wall motion abnorm or cavity dilatation on echocavity dilatation on echo

• Ventricular TachycardiaVentricular Tachycardia

Who do I send right to Who do I send right to cath?cath?

• High pre-test probability and High pre-test probability and classic symptomsclassic symptoms

• Previously unknown abnormal Previously unknown abnormal LV functionLV function

• Recurrent CP with recent Recurrent CP with recent negative or equiv stress testnegative or equiv stress test

Take Home MessagesTake Home Messages

• Most hospitalized pts will receive Most hospitalized pts will receive imaging stress testingimaging stress testing

• Exercise EKG is preferable to Exercise EKG is preferable to pharmacologic stress unless pt can’t pharmacologic stress unless pt can’t achieve target HR or has LBBB/pacerachieve target HR or has LBBB/pacer

• Avoid neg chronotropes if stress test Avoid neg chronotropes if stress test is to r/o CADis to r/o CAD

Take Home MessagesTake Home Messages

• Nitroglycerin is the most overused, Nitroglycerin is the most overused, toxic med in the hospitaltoxic med in the hospital

• Discharge for elective stress testing Discharge for elective stress testing may be appropriate for low risk may be appropriate for low risk patientspatients

• Catheterization is more cost-effective Catheterization is more cost-effective for high-risk patients or recurrent for high-risk patients or recurrent chest pain despite negative studieschest pain despite negative studies