CLINICAL-VALUE OF ACUTE REST TC-99M TETROFOSMIN TOMOGRAPHIC MYOCARDIAL PERFUSION IMAGING IN PATIENTS WITH ACUTE CHEST PAIN AND NONDIAGNOSTIC ELECTROCARDIOGRAMS

Objectives. We sought to evaluate the clinical use and cost analysis o f acute rest technetium-99m (Tc-99m) tetrofosmin single-photon emissio n computed tomographic (SPECT) myocardial perfusion imaging in patient s with chest pain and a normal electrocardiogram (ECG). Background. Cu rrent approaches used in emergency departments (EDs) for treating pati ents presenting with chest pain and a nondiagnostic ECG result in poor resource utilization. Methods. Three hundred fifty-seven patients pre senting to six centers with symptoms suggestive of myocardial ischemia and a nondiagnostic ECG underwent Tc-99m tetrofosmin SPECT during or within 6 h of symptoms. Follow-up evaluation was performed during the hospital period and 30 days after discharge. All entry ECGs, SPECT ima ges and cardiac events were reviewed in blinded manner and were not av ailable to the admitting physicians. Results. By consensus interpretat ion, 204 images (57%) were normal, and 153 were abnormal (43%). Of 20 patients (6%) with an acute myocardial infarction (MI) during the hosp ital period, 18 had abnormal images (sensitivity 90%), whereas only 2 had normal images (negative predictive value 99%). Multiple logistic r egression analysis demonstrated abnormal SPECT imaging to be the best predictor of MI and significantly better than clinical data. Using a n ormal SPECT image as a criterion not to admit patients would result in a 57% reduction in hospital admissions, with a mean cost savings per patient of $4,258. Conclusions. Abnormal rest Tc-99m tetrofosmin SPECT imaging accurately predicts acute MI in patients with symptoms and a nondiagnostic ECG, whereas a normal study is associated with a very lo w cardiac event rate. The use of acute rest SPECT imaging in the ED ca n substantially and safely reduce the number of unnecessary hospital a dmissions. (C)1998 by the American College of Cardiology.