Asymptomatic Cardiac Ischemia Pilot (ACIP) Study

Objectives

To assess the feasibility of and test the methodology for a full-scale clinical trial of therapies for asymptomatic cardiac ischemia.

Background

Asymptomatic cardiac ischemia, frequently designated as silent myocardial ischemia, refers to episodes of objectively demonstrable transient ischemia in the absence of symptoms. Asymptomatic ischemia has been linked with sudden death or myocardial infarction. It is estimated that in the United States over six million patients have chronic, symptomatic coronary heart disease and up to three million of these may exhibit transient asymptomatic myocardial ischemia.

Subjects

Men and women, with coronary artery disease documented angiographically, who had evidence of ischemia on both stress (exercise) testing and 48-hour ambulatory electrocardiogram monitoring (AECG) and were amenable to revascularization. The 618 patients, stratified by presence or absence of angina, included 94 women (15%) and 524 men (85%), with 14 percent minorities.

Design

A total of 1,959 patients were screened by AECG monitoring; 49 percent had asymptomatic ischemia. The 558 patients whose data are in the data set were randomized to one of the three treatment strategies: 183 to angina-guided medical strategy with titration of anti-ischemic medication to relieve angina; 183 to angina-guided plus AECG ischemia-guided medical strategy with titration of anti-ischemic medication to eliminate both angina and AECG ischemia; and 192 to revascularization by angioplasty or bypass surgery. The primary outcome was the absence of ischemia at twelve weeks.

Conclusions

Twelve-week, one year and two year follow up results have been published. Two-year follow-up results of patients randomized to initial strategies of medical therapy versus revascularization were published in Circulation in April, 1997 (Davies R.F., Goldberg A.D., Forman, S., et al.: Asymptomatic Cardiac Ischemia (ACIP) Study Two-Year Follow-Up: Outcomes of Patients Randomized to Initial Strategies of Medical Therapy versus Revascularization. Circulation 1997 95:2037-2043). Two years after randomization, the total mortality was 6.6 percent in the angina-guided drug therapy strategy (n=183), 4.4 percent in the ischemia-guided drug therapy strategy (n=183) , and 1.1 percent in the revascularization strategy (n=192). The rate of death or myocardial infarction was 12.1 percent in the angina-guided strategy, 8.8 percent in the ischemia-guided strategy, and 4.7 percent in the revascularization strategy. The authors concluded that a strategy of initial revascularization appeared to improve the prognosis of this population compared with angina-guided medical therapy.

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