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Every year more than 6 million patients arrive at the hospital emergency department (ED) with chest pain or other symptoms that suggest acute cardiac ischemia (i.e., heart attack or unstable angina). Most patients without obvious ischemic electrocardiogram (ECG) changes who are hospitalized or observed in special ED units, ultimately prove not to have acute ischemia. However, a few patients who actually have acute ischemia are mistakenly sent home from the ED. Fortunately, imaging coronary blood flow in the ED can reduce unnecessary hospitalization of some patients without reducing appropriate hospitalization of patients with acute cardiac ischemia, according to a study that was supported in part by the Agency for Healthcare Research and Quality (HS09110).
Researchers led by Harry P. Selker, M.D., of Tufts-New England Medical Center, randomized 2,475 ED patients at 7 hospitals who were suspected of having acute cardiac ischemia but who had normal or nondiagnostic initial ECG changes of acute ischemia, to one of two evaluation strategies: the usual ED evaluation or the usual evaluation supplemented with results from a resting single-photon-emission computed tomography (SPECT) myocardial perfusion imaging with injection of 20 to 30 mCi of Tc-99m sestamibi. This provides imaging of myocardial blood flow at the time of ED evaluation, giving the ED physician quick information.
The researchers examined the effect of each strategy on the appropriateness of the triage decision either to admit a patient to the hospital for observation or to discharge the patient directly home. Among patients with acute cardiac ischemia, there were no differences in ED triage decisions between those receiving standard evaluation and those who also had sestamibi scan. Among patients with a heart attack, 97 vs. 96 percent (with scan) were hospitalized, and among those with unstable angina, 83 vs. 81 percent (with scan) were hospitalized. However, among patients who did not have acute cardiac ischemia, only 42 percent of scanned patients were unnecessarily hospitalized compared with 52 percent of usual care patients.
More details are in "Myocardial perfusion imaging for evaluation and triage of patients with suspected acute cardiac ischemia," by James E. Udelson, M.D., Joni R. Beshansky, R.N., M.P.H., Daniel S. Ballin, M.D., and others, in the December 4, 2002, Journal of the American Medical Association 288(21), pp. 2693-2700.
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