Stress ECG is still Viable in 2016 Suleiman M Kharabsheh, MD, FACC Consultant Invasive Cardiologist KFHI KFSHRC-Riyadh
Stress ECG Do we still need stress ECG with all the advances we have in the CV field? What are the indications or uses for it? Does EST provide an additional diagnostic or prognostic data over the currently available contemporary tests?
It s not only an ECG! Functional Capacity Symptom reproduction ECG changes HR rise and recovery BP rise and recovery Arrhythmias
Intro A 55 year old male, smoker, referred to you from his family physician with complaint of atypical chest pain over the past 3 months He has normal ECG at baseline And had fair functional status What diagnostic test would you do next?
Intro Send him for cardiac catheterization Do stress Echocardiogram Do MPI EST
Diagnostic Accuracy
Indications for EST Diagnosis of Obstructive CAD Adult patients (including those with complete right bundlebranch block or less than 1 mm of resting ST depression) with an intermediate pretest probability of CAD (class I) Patients with Vasospastic angina (class IIa) ACC/AHA Guidelines 2002
Confounders of Stress ECG Interpretation Resting ST depression LVH with repolarization abnormality Digoxin RBBB LBBB Drugs (BB, Nitrates) Am J Cardiol 1986;57:661-5.
Indications for EST RISK ASSESSMENT AND PROGNOSIS IN PATIENTS WITH SYMPTOMS OR A PRIOR HISTORY OF CAD
Risk Assessment & Prognosis
Risk Assessment & Prognosis Two early influential studies of exercise treadmill testing and prognosis were reported from the: 1. Duke Cardiovascular Disease Databank 2. Coronary Artery Surgery Study (CASS) Registry
Duke database Early positive exercise test result (ST depression greater than or equal to 1 mm in the first 2 stages of the Bruce protocol) identified a high-risk population, whereas patients who could exercise into stage IV were at low risk regardless of the ST response Circulation 1978;57:64-70
Nomogram of the prognostic relations embodied in the treadmill score Raymond J. Gibbons et al. Circulation. 1997;96:345-354 Copyright American Heart Association, Inc. All rights reserved.
CASS Registry Weiner and Colleagues analyzed 4083 medically treated patients and identified as: high risk ( > 0.1 mv of exercise- induced ST-segment depression and inability to complete stage I of the Bruce protocol), 12% These patients had an average annual mortality rate of 5% per year low-risk, Patients who could exercise to at least stage III of the Bruce protocol without ST-segment changes (34%) Estimated annual mortality less than 1% J Am Coll Cardiol 1984;3:772-9
Use of Exercise Test Results in Patient Treatment a low-risk exercise test result can be treated medically a high risk exercise test result should usually be referred for cardiac catheterization Patients with an intermediate-risk should be referred for additional testing, either cardiac catheterization or an exercise imaging study (LV dysfunction)
Patients with ACS low-risk patients, testing can be performed when patients have been free of active ischemic or heart failure symptoms for a minimum of 8 to 12 hours Intermediate-risk patients can be tested after 2 to 3 days Clinical Practice Guideline No. 10. AHCPR publication No. 94-0602.
Chest Pain Centers Use of early exercise testing in emergency department chest pain centers improves the efficiency of management of these patients (and may lower costs) without compromising safety N Engl J Med 1998;339:1882-8.
Stress testing following MI Exercise stress testing is an invaluable tool for risk stratification post-mi. In the early days post MI (days 3-7), a low level stress test limited to 5 METS, 75% of MPHR or 60% of MPHR on β blockers, is very helpful in patients who were treated conservatively with no revascularization to assess for ischemia at low workload, arrhythmias, to start cardiac rehabilitation and gaining self confidence. Late post-mi (4-6 weeks), symptom limited stress testing is usually performed to assess revascularization, medical therapy or need for any further interventions.
EST Post MI Exercise testing after myocardial infarction appears to be safe A meta-analysis that evaluated exercise testing within 6 weeks of myocardial infarction demonstrated the odds ratio for cardiac death among those with exercise induced ischemic ST-segment depression (greater than or equal to 1 mm) to be 1.7 compared with those without. Am J Cardiol 1996;78:1327-37
EST Post MI Failure to achieve 5 METs during treadmill exercise post MI is associated with a worse prognosis Failure to increase systolic blood pressure by 10-30 mm Hg during exercise testing has been shown to be an independent predictor of adverse outcome in patients after myocardial infarction
Strategies for exercise test evaluation soon after myocardial infarction. Raymond J. Gibbons et al. Circulation. 1997;96:345-354 Copyright American Heart Association, Inc. All rights reserved.
Cardiac Rehabilitation Exercise testing in cardiac rehabilitation is essential in development of the exercise prescription to establish a safe and effective training intensity Symptom-limited exercise testing before program initiation is needed for all patients in whom cardiac rehabilitation is recommended Circulation 1989;80:234-44
EST for HF / Heart Tx Evaluation of exercise capacity and response to therapy in patients with heart failure who are being considered for heart transplantation (Class I)
Valvular Heart Disease AS AR MS MR
Investigation of Heart Rhythm disorder VT, exercised induced ectopy carries 3 times mortality compared to resting ectopy WPW assess risk of RVR with atrial Arrhythmias Assess effective AF rate control Sinus node dysfunction and chronotropic incompetence Med Clin North Am 1984;68:1139-52
Other Variables of value derived from EST
HR rise & recovery The HR should decrease by at least 12 beats in the first minute of recovery, which is mediated through vagal reactivation. Otherwise, recovery is considered abnormal, which has a bad prognosis, with a 6-year mortality 2-3 times greater than those with normal recovery.
BP rise & recovery an abnormal BP recovery, defined by the SBP at 3 minutes of recovery over an SBP at 1 minute of recovery >1, is associated with a greater likelihood of severe angiographic CAD. An abnormal rise of SBP to a level > 214 mm Hg in patients with a normal resting BP predicts an increased risk for future sustained hypertension, estimated at approximately 10% to 26% over the next 5 to 10 years. However, in adults evaluated for CAD, exercise hypertension is associated with a lower likelihood of angiographically severe disease. Am J Cardiol 1999;83:371-5 Circulation 1999;99:1831-6
ST-T changes Leads V4, V5, and V6 are the most sensitive leads for detecting the ST depression of subendocardial ischemia V5 alone is often the single best lead for this purpose ST depression does not localize the coronary artery responsible for the ischemic ST segment depression confined to the inferior leads II and avf is most often a false positive response Greater ST segment depression involving multiple leads usually signifies extensive myocardial ischemia
Transient LBBB
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