TC-99M SESTAMIBI MYOCARDIAL PERFUSION IMAGING IN THE EMERGENCY ROOM EVALUATION OF CHEST PAIN

Objectives. The purpose of this investigation was to evaluate the prac ticality and short term predictive value of acute myocardial perfusion imaging with technetium-99m sestamibi in emergency room patients with typical angina and a normal or nondiagnostic electrocardiogram (ECG). Background. Accuracy of emergency room chest pain assessment ment may be improved when clinical and ECG variables are used in conjunction w ith acute thallium-201 myocardial perfusion imaging. Technetiun-99m se stamibi is a new radioisotope that is taken up by the myocardium in pr oportion to blood flow, but unlike thallium-201, it redistributes mini mally after injection. Technetium 99m sestamibi can thus be injected d uring chest pain, and images acquired 1 to 2 h later (when patients ha ve been clinically stabilized) will confirm whether abnormalities of p erfusion were present at the time of injection. Methods. One hundred t wo emergency room patients with typical angina (on the basis of a stan dardized angina questionnaire) and a normal or nondiagnostic ECG had a technetium-99m sestamibi injection during symptoms and were followed up for occurrence of adverse cardiac events (cardiac death, nonfatal m yocardial infarction, coronary angioplasty, coronary surgery or corona ry thrombolysis). Results. Univariate predictors of cardiac events inc luded the presence of three or more coronary risk factors (p = 0.009, risk ratio 3.3) and an abnormal or equivocal acute technetium-99m sest amibi scan (p = 0.0001, risk ratio 13.9). Multivariate regression anal ysis identified an abnormal perfusion image as the only independent pr edictor of adverse cardiac events (p = 0.009). Of 70 patients with a n ormal perfusion scan, only 1 had a cardiac event compared with 15 pati ents with equivocal scans or 17 patients with abnormal scans, with a c ardiac event rate of 13% and 71%, respectively (p = 0.0004). Conclusio ns. Initial myocardial perfusion imaging with technetium-99m sestamibi when applied in emergency room patients with typical angina and a nor mal or nondiagnostic ECG appears to be highly accurate in distinguishi ng between low and high risk subjects.