The majority of studies were not blinded by outcome. Participants in more then half of the studies in both groups were prospectively and/or consecutively enrolled. Routine screening for MI was more frequent in SE than TI studies, but results of the test were used to refer to angiography more often in TI than SE studies. The number of patients with cardiac disease, diabetes or congestive failure was similar across SE and TI studies, but patients evaluated with SE had more previous vascularisation and more patients were using β-adrenergic antagonists.
The unadjusted MI/death rates were 8.1 per cent for TI and 7.5 per cent for SE. SE was found to be superior for predicting a postoperative cardiac event than TI (LR 4.09, 95% CI: 3.21, 6.56 versus LR 1.83, 95% CI: 1.59, 2.10; p=0.0001) with fewer SE false negatives, based on all studies. Where direct comparisons of SE to TI were made, no statistical difference was found between tests, based on seven studies. Including only vascular studies, studies with blinding procedures, studies completed after 1995 or studies with routine screening for post-operative MI did not significantly change the results of the meta-analysis. Significant statistical heterogeneity was reported. However, a negative SE was a better predictor of an uneventful operation than TI (-LR 0.23, 95% CI: 0.17, 0.32 versus 0.44, 95% CI: 0.36, 0.54, P<0.02).
The rate of referral to angiography was more frequent in patients screened with TI than SE (LR 29.1, 95% CI: 18.5, 39.6 versus LR 12.0, 95% CI: 8.7, 16.2; p=0.02). The percentage of patients who were revascularised was greater in SE than TI tests (LR 57.5, 95% CI: 34.0, 81.0 versus LR 29.0, 95% CI: 18.0, 30.1; p=0.05).