Indications for Exercise Echocardiography Reserve of Ventricular Function Detection of coronary artery disease/ myocardial ischemia Risk assessment/ prognosis Viability/ suitability for revascularization Timing of intervention in valvular heart disease Adequacy of therapy
Limitations of Exercise Echocardiography Inability to exercise: orthopedic, neurological, pulmonary or psychological Inability to image: acoustic windows; hyperinflation, obesity Delay in getting into position for imaging, after completing exercise Inability to lie on side and/or breath-hold (briefly)
Echo acoustic images: identifying endocardium and myocardium from ACCSAP7
Echo contrast to aid in identifying endocardium ACCSAP7
Sensitivity and Specificity (continued) SpPin: for a specific test (few false positives); positive test, rules in SnNout: for a sensitive test (few false negatives); negative test, rules out Wall motion (echocardiography) is more specific than symptoms or ECG Sensitivity is greatly influenced by adequacy of exercise, in terms of both exercise duration/ level, and double product (peak systolic blood pressure x peak exercise heart rate). Positive predictive value (PPV) = TP/ (TP = FP) Negative predictive value (NPV) = TN/ (TN + FN)
Bayesian principle Conditional Probability All good clinicians use all the diagnostic information they have; test results should be taken ‘in-context’. Accuracy of any test depends not only on the test’s sensitivity/ specificity, but also the pre-test probability of disease. –Consider the clinical usefulness of screening for lung cancer in kindergarten children.
Limitations of Exercise Electrocardiography (ECG)
Exercise vs. Pharmacological Echo as reported in JACC (2003;42:954-970) and cited by ACCSAP7
Exercise myocardial perfusion imaging (nuclear) vs. echocardiography as reported in Eur Heart J(2003;24;789-800) and cited by ACCSAP7
“Party Line” Nuclear stress testing is more sensitive for detecting myocardial ischemia. Echo has more false negatives. Exercise echo is more specific for myocardial ischemia than nuclear. Nuclear has more false positives.
Guideline and Appropriateness Concepts regarding work-up of suspected coronary artery disease (CAD) Careful history is most important. Further work-up should be guided by clinical likelihood of CAD. Exercise ECG is preferred, if patient can exercise and resting-ECG is normal. Value of stress testing, to infer CAD, is highest among intermediate probability patients.
Guideline and Appropriateness Concepts regarding work-up of suspected coronary artery disease (CAD) (2) Stress imaging should NOT be used as initial evaluation of low probability patients, because of high likelihood of false positives leading to unnecessary work-up. Coronary angiography is recommended for high-risk (of events) patients, regardless of symptom severity. However, among patients with known CAD looking for silent ischemia, among asymptomatic patients is eschewed.
Pre-test likelihood of coronary artery disease (CAD) (NEJM 1979;300:1350-1358
Prognosis: Duke score of exercise ECG Duration of exercise on Bruce protocol - 5X (ST depression in mm) - 4x (angina index; 1 point for any chest pain; 2 points if angina was limiting symptom). Low risk >+5 annual mortality 0.25% Intermediate -10 to +4 annual mortality 1.25% High risk <-10 annual mortality 5.0%
Predicting multi-vessel CAD, from Stress Test Results Early positive= Stage I of Bruce or ‘low-level’ Markedly positive ECG: ST >2 mm depression or ST-elevation Prolonged: ST depression >8 minutes into recovery Fall in systolic blood pressure, with exercise; especially if accompanied by signs or symptoms
Prognosis: Exercise Duration + 2 mm ST depression from JACC (2000;36:2140-2145) as cited in ACCSAP7
Prognosis: Chronotropic incompetence from Circulation (1996;93:1520-1526) as cited in ACCSAP7
Prognosis: Exercise ST-elevation as shown in ACCSAP7
Prognosis: extent of echo wall motion abnormality reported in JACC (2003;42:1084-1090) and cited in ACCSAP7
Exercise Echocardiography: Appropriateness JACC 2008;51:1127-1147. Indication categories –Detection of CAD/Risk Assessment: symptomatic –Detection of CAD/Risk Assessment: asymptomatic –Detection of CAD/Risk Assessment: co morbidities –Risk assessment with prior test results –Risk assessment: Pre-operative for non-cardiac surgery –Risk assessment: after acute coronary syndrome (ACS) –Risk assessment: after revascularization (PCI or CABG) –Assessment of viability/ Ischemia –Hemodynamic assessment
Summary of Exercise Echo Why did you order this test? How will you use the results, of this test, to better manage your patient? Have you taken into account the limitations of these test data?