Activity of transient myocardial ischemia out of hospital in coronary artery disease and implications for management

Abstract

The management of patients with angina pectoris is based largely on the severity of symptoms, coronary anatomy and left ventricular function. The outcome for these patients is highly variable and depends largely on the degree of ischemic damage to the left ventricular myocardium. Recent work suggests that exercise-induced myocardial ischemia with or without angina is associated with a poor prognosis. Ambulatory monitoring of the electrocardiogram has revealed that most patients have frequent and prolonged episodes of transient ischemia out of hospital. These episodes are often asymptomatic and associated with ordinary everyday activities. In addition, ambulatory monitoring has demonstrated that transient ischemia during daily life has a circadian variation with exacerbations and peak density of ischemia in the first 4 to 6 waking hours of the day. Further studies have demonstrated that regional decreases in coronary blood flow occur during these ischemic episodes and have the same features seen out of hospital on continuous monitoring. These newly noted characteristics of transient ischemia raise a number of practical questions for treatment. Is it necessary to relieve all ischemic activity quite apart from that which occurs with chest pain? Does present use of antianginal medication neglect the early morning increases in transient ischemia that occur, and are different dosage regimens required to treat ischemia adequately? Does suppression of all ischemic activity further protect myocardium and improve prognosis for the patient?