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Patients who are suspected of having a heart attack (acute myocardial infarction, AMI) on arrival at the hospital and have electrocardiogram (ECG) abnormalities typical of heart attack, such as ST segment elevation, usually undergo diagnostic coronary angiography (x-ray imaging of the heart after infusion of a contrast dye via a catheter) and coronary angioplasty or coronary artery bypass surgery. A new study concludes that suspected heart attack patients with seemingly normal ECGs, who have similar long-term rates of reinfarction and death as AMI patients with ECG abnormalities, should also undergo these procedures.
The study was supported in part by the Agency for Healthcare Research and Quality (HS08362) with Grant S. Scull, M.D., of the University of Washington, as lead author. Dr. Scull and colleagues compared treatments, hospital course, and outcomes in 308 AMI patients without ST segment elevation on ECGs who were treated at hospitals where the initial treatment strategy favored early angiography and appropriate intervention (angioplasty or bypass surgery) versus 1,327 similar patients who were treated at hospitals that favored a more conservative initial approach using medications only.
Hospitals favoring an early invasive strategy performed coronary angiography within 6 hours of admission on 25 percent or more of patients with chest pain and nondiagnostic ECG changes. About 60 percent of patients treated at these hospitals had early angiography versus 8 percent of patients treated at hospitals favoring conservative treatment, and 45 vs. 6 percent had early angioplasty performed. Patients treated in hospitals favoring the early invasive strategy had a lower 30-day (5.5 vs. 9.5 percent) and 4-year mortality rate (20 vs. 37 percent). In fact, patients who actually underwent angiography within 6 hours of admission had a remarkably low mortality rate (1 vs. 7 percent died in the hospital and 10 vs. 33 percent had died 4 years later). This suggests that early myocardial salvage may play an important role in survival, and that early angiography without prior noninvasive testing is beneficial in select patients.
More details are in "Early angiography versus conservative treatment in patients with non-ST elevation acute myocardial infarction," by Dr. Scull, Jenny S. Martin, R.N., W. Douglas Weaver, M.D., F.A.C.C., and Nathan R. Every, M.D., M.P.H., in the March 15, 2000, Journal of the American College of Cardiology 35, pp. 895-902.
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