Occurrence and Diagnostic Importance of Postural ST-Segment Depression in Ambulatory Holter Monitoring in Male Patients After Myocardial Infarction

Abstract

Ambulatory Holter monitoring is widely accepted and most often used in clinical practice to detect and characterize silent myocardial ischemia in patients with coronary artery disease (CAD) and after myocardial infarction (MI). It has been demonstrated that occurrence of ST-segment depression after MI, painful and silent, is correlated with a poor prognosis (3,4,11–13a, 16–19,21,22,24,27,28). The value of ambulatory Holter monitoring in the assessment of activity of CAD clearly depends on the reliability of ST-segment changes as a marker of myocardial ischemia. Many factors can produce ST-segment displacement during electrocardiographic (ECG) ambulatory recording and result in“false-positive”diagnosis of silent myocardial ischemia. ST-segment depression of 1 mm or more may occur during body position change, hyperventilation, or Valsalva maneuver, so it is recommended to perform provocative maneuvers at the beginning of ambulatory Holter monitoring (14). Despite this recommendation, few studies have examined the occurrence of positional ST-segment displacement in normal subjects, and the results vary widely, from 0% to 30% (1,2,6,29). In one study on this problem concerning patients after MI, Currie at al. found positional significant (of lmm or more) ST-segment depression in 20% of patients in early stage after MI and in 10.7% of patients in late stage after MI (4).