Total ischemic burden: definition, mechanisms, and therapeutic implications.

The concept of the total ischemic burden includes all types of ischemia encompassing both silent and symptomatic ischemic episodes. This concept is currently causing a re-evaluation of current therapeutic goals for patients with coronary heart disease. Although the mechanism of cardiac pain is still unclear, we do have some information about other pathophysiologic mechanisms at work in this disorder. We think of ischemia as occurring secondary to reduced supply (primary ischemia), increased demand (secondary ischemia), or a combination of the two (mixed ischemia). Because of the lower heart rate associated with many episodes of ischemia during everyday activities, suggesting that vasoconstriction is playing a role in the patient's supply/demand imbalance, calcium antagonists appear to be particularly useful agents for the treatment of vasoconstriction in patients with angina.