Effect of transient ischaemia on left ventricular function and prognosis.

Transient myocardial ischaemia is associated with a rapid reduction in ATP concentration, depletion of glycogen storage, and transient from aerobic to anaerobic metabolism. Repeated ischaemic episodes are associated with structural changes, some of which are transient, while others are permanent. These changes affect myocardial cells, collagen matrix and lead to increased amounts of fibrous tissue, which may impair both systolic and diastolic left ventricular function. Ischaemic changes, whether silent or symptomatic, during exercise testing are independent predictors of worse prognosis beyond the extent of coronary disease. Abolition of exercise-induced ischaemia, either by coronary bypass surgery or by medical therapy is associated with improved outcome. Ischaemic episodes during daily life are independent predictors of future cardiac events beyond results of exercise testing, extent of coronary disease or left ventricular function. Impairment of systolic and diastolic function persists from hours to days after transient ischaemia. Abolition of myocardial ischaemia, either by medical therapy or coronary angioplasty, has been shown to improve both systolic and diastolic function. It seems, therefore, that prevention of ischaemia is fully justified as it preserves the metabolic and functional state of the myocardium and improves prognosis.