Ambulatory ECG, Myocardial Ischemia and Risk Stratification

Abstract

The ECG method is an accepted method for diagnosing myocardial ischemia. However, the diagnostic accuracy is highly dependent of the pre-test prevalence of coronary artery disease (CAD) in the individual patient.

The accepted criteria for this diagnosis is reversible ST-segment depression, horizontal or downsloping, of at least 0.1 millivolt, and in the case of Ambulatory ECG, for at least 1 minute (Cohn et al, Circulation 1987; 75(Suppl II): 11–51).

In order to safely diagnose reversible myocardial ischemia, a pre-test likelihood of 75% of the disease is needed to reach > 90% accuracy of CAD (Pietrowicz et al, Annals of Noninvasive Electrocardiology 1998; 3:131–138).

The ECG method generally used has by tradition been Exercise Tolerance test (ETT). for some years, Ambulatory ECG (Amb ECG) has also been used as a practical replacement for ETT, especially in screening procedures for myocardial ischemia.

The question that arises today is whether Amb-ECG may be used as a screening tool to identify apparently healthy groups with high risk for future Myocardial Infarction. if this is possible, pharmacological risk factor treatment may reduce the morbidity and mortality within this high-risk group. Also, as a consequence, and in spite of traditional cardiovascular risk factors, a low-risk group may be defined. Within this group, it will not be feasible to affect the cardiovascular risk factors, and thereby reduce the cost for pharmacological treatment within the group of apparently healthy high-risk individuals.