Accuracy of imaging technologies in the diagnosis of acute cardiac ischemia in the emergency department: A meta-analysis

Study objective: We sought to quantitatively evaluate the evidence on the d iagnostic performance of imaging technologies (including rest and stress ec hocardiography and technetium-99m sestamibi scanning) far the diagnosis of acute cardiac ischemia and acute myocardial infarction in the emergency dep artment. Methods: We conducted a systematic review and meta-analysis of the English- language literature published between 1966 and December 1998. Both prospect ive and retrospective studies qualified for the assessment of diagnostic pe rformance. Diagnostic performance was assessed by means of random-effect es timates of test sensitivity, specificity, and the diagnostic odds ratio and was summarized by using summary receiver-operating characteristic curves. Results: Diagnostic accuracy was evaluated in 10 studies of rest echocardio graphy, 2 studies of dobutamine stress echocardiography, and 6 studies of t echnetium-99m sestamibi scanning, However, only 3 rest echocardiography and 5 technetium-99m sestamibi studies evaluated patients strictly in the ED s etting. Patient populations were often highly selected to represent low- or moderate-risk groups. When limited to ED studies, rest echocardiography sh owed excellent sensitivity of 93% (95% CI, 81% to 97%) and goad specificity of 66% (95% CI, 43% to 83%). The results were similar when all studies wer e considered, including data from reports of admitted patients and patients sent to the cardiac care unit. There was insufficient literature on stress echocardiography in the ED to properly assess the technology. Technetium-9 9m sestamibi scanning also showed excellent sensitivity (range, 91.5% to 10 0%) and good specificity (range, 49.3% to 84.4%) for acute myocardial infar ction; for acute cardiac ischemia, the random-effects pooled sensitivity wa s 89% (95% CI, 73% to 96%), and the pooled specificity was 77% (95% CI, 63% to 87%). Conclusion: For selected low- and moderate-risk patient groups, echocardiog raphy and technetium-99m sestamibi imaging appear to have very good diagnos tic performance with a similar sensitivity and specificity profile. More ev idence should be accumulated on their performance specifically in the ED se tting.