The concept of total ischaemic burden: clinical significance.

Quantification of spontaneous ischaemic episodes during daily activities has been made possible by the introduction of continuous ambulatory ECG (Holter) monitoring. In view of the fact that the large majority of ischaemic patients exhibit both painful and silent myocardial ischaemia, the concept of the total ischaemic burden has been developed. This takes account of the total number, duration and extent of ischaemic episodes over 24 h, in order to provide an assessment of the severity of patients' ischaemic heart disease. Although it is uncertain whether patients with positive exercise tests and both silent and symptomatic ischaemic episodes have a higher risk for myocardial infarction, several studies have shown that these patients have a higher total ischaemic burden. In contrast, despite having high-grade stenosis and positive exercise tests, patients with only silent ischaemic episodes, or without ischaemic episodes during continuous monitoring, seem to experience lower mortality. In general, prognosis is not determined by the presence or absence of absence of anginal pain but by the amount of ischaemia.