PREVALENCE OF PSEUDOISCHEMIC ST-SEGMENT CHANGES DURING AMBULATORY ELECTROCARDIOGRAPHIC MONITORING

Ambulatory electrocardiographic monitoring (AEM) is frequently used to record ST-segment changes suggesting transient myocardial ischemia in patients with coronary artery disease.1 AEM has also been used to assess the efficacy of antiischemic therapy.2-6 The value of AEM for ischemia monitoring is dependent on the ST-segment changes detected being reliable markers for transient myocardial ischemia. Frequently, before AEM and exercise treadmill tests, technicians perform provocative maneuvers (i.e., position change, hyperventilation and Valsalva maneuver) to elicit ST-segment or T-wave changes that may interfere with electrocardiographic determinations of transient myocardial ischemia. Despite this practice, there are few studies examining the incidence of these electrocardiographic artifacts. One such study found that in subjects without cardiac disease, ST-segment depression or T-wave changes suggesting ischemia seldom occurred.7 The aim of this study was to determine the prevalence of these pseudoischemic ST-segment or T-wave changes in cardiac patients referred for AEM. © 1992.