State of the art in stress testing and ischaemia monitoring

Abstract

Electrocardiography remains the most widely used method for detecting myocardial ischemia. ST segment abnormalities in the resting 12-lead electrocardiogram in subjects with angina and coronary risk factors seem to definitely indicate ischemic heart disease and an adverse prognosis. ST depression during exercise testing is the first line provocative test for ischemic heart disease although it has a mean sensitivity of only 68% and a slightly higher specificity (77%). The presence or absence of chest pain in patients with an ischemic ST response to exercise testing does not change the risk of future ischemic events. However, ST depression during the recovery period is associated with increased risk both for acute coronary events and coronary death, whereas silent ischemia during recovery is an even stronger predictor than during exercise. The amplitude of ST depression has not been documented to reflect the magnitude of ischemia. Therefore, new methods are under investigation such as adding R and Q wave amplitude criteria, maximal ST/heart rate slope, linear regression analysis of the heart rate related change in ST depression and a score integrating ST segment amplitude and slope changes. The demonstration of episodic ST segment depressions in the ambulatory setting, even without accompanying chest pain, are an expression of transient ischemia and such episodes seem to represent a poor prognosis. In the hospital setting, ST depression detected by continuous monitoring is related to the clinical outcome. ST segment monitoring during the first 6-9 hours after coronary care unit admission provides important prognostic information on-line and considerably improves early risk stratification. Such continuous ST monitoring overcomes some of the limitations of static monitoring, as it improves the likelihood of capturing the maximal point of ST deviation, as well as early episodes of reocclusion that are manifest as recurrent ST elevation.