When compared with intensive drug therapy, percutaneous coronary intervention (PCI, angioplasty) was more beneficial in reducing the long-term risk of major cardiac events among heart attack survivors with “silent ischemia”, according to a study in the May 9 issue of JAMA.
Cardiac ischemia is caused by insufficient blood flow to the heart muscle tissue. Silent ischemia can occur without accompanying signs or symptoms of angina (chest pain due to inadequate supply of oxygen to the heart muscle), but can be detected by electrocardiogram (ECG) and other techniques. Silent ischemia has been shown to predict adverse prognosis in patients after myocardial infarction (MI, heart attack), coronary artery bypass graft surgery, and PCI, with or without stenting, according to background information in the article. However, the effect of PCI on the long-term prognosis of patients with silent ischemia after a heart attack is not known.
Paul Erne, M.D., of the Division of Cardiology, Kantonsspital Luzern, Luzern, Switzerland, and colleagues conducted a randomized, unblinded, controlled trial from May 2, 1991, to February 25, 1997, to determine whether PCI compared with drug therapy improves long-term outcome of asymptomatic patients with silent ischemia after a heart attack. A total of 201 patients with a recent heart attack, silent myocardial ischemia verified by stress imaging, and one- or two-vessel coronary artery disease took part in the study. Ninety-six patients underwent PCI, and 105 patients received intensive anti-ischemic drug therapy. All patients received 100 mg. per day of aspirin and a statin (cholesterol-lowering) drug. Follow-up ended on May 23, 2006.
Patients in the PCI group experienced 27 major adverse cardiac events during an average follow-up of 10.2 years. During the same period, 67 adverse cardiac events occurred in the anti-ischemic drug group. This corresponds to an absolute event reduction of 6.3 percent per year. The rate of ischemia among patients in the PCI group was 11.6 percent at the final follow-up, compared with 28.9 percent among patients in the drug therapy group, despite fewer drugs.
“We found a persistent benefit of PCI compared with optimized drug therapy,” the authors report. “This benefit became apparent only after two years of observation, with survival curves continuously diverging up to the final follow-up after ten years.”
“This is the first, to our knowledge, long-term outcome study of an invasive therapy compared with an intensive anti-ischemic drug therapy in asymptomatic patients with silent ischemia after a recent MI,” the authors write.
“Our findings argue for an ischemic-targeted approach to PCI among asymptomatic survivors of MI,” they conclude.