Cost-effectiveness and accuracy of exercise stress echocardiography in thenon-invasive diagnosis of coronary heart disease

Background: Exercise stress echocardiography (ESE) is a more recent form of totally non-invasive stress testing which like exercise thallium SPECT sci ntigraphy (ETS) was developed to overcome the known limitations of ECG stre ss testing, namely the limited diagnostic accuracy and the inability of ECG stress testing to site the region of coronary artery disease (CAD) induced ischaemia. Aims: To determine the sensitivity and specificity (and overall accuracy) o f ESE in a group of patients referred for ETS imaging and compare the relat ive costs of each technique. Methods: One hundred and fifteen patients referred for ETS consented to a s imultaneous ESE. Of this group, 59 patients underwent coronary angiography which was utilised as the gold standard. Results: The feasibility of ESE was 97% (112 of 115 patients of the total s tudy population and 57 of the 59 patients who underwent coronary angiograph y). Of the 59 patients undergoing coronary angiography, the sensitivity of ESE and ETS were not significantly different (84.1% versus 91.3% respective ly). However, despite the apparent marked difference in specificity (92.3% versus 61.5% respectively), p = NS (Fisher's exact test) as there were only 13 normals in the group who underwent coronary angiography. Overall accura cy was also closely similar (86.0% versus 84.7% respectively) and therefore also not significantly different. By contrast, agreement with coronary ang iography as measured by the kappa statistic (k +/- SEk) was good for ESE (0 .66+/-0.11) but only moderate for ETS (0.54+/-0.13). Moreover, there was a cost saving of at least $594.00 per patient in favour of ESE. Conclusion: ESE is a totally non-invasive, sensitive, specific and cost-eff ective imaging modality for the detection and localisation of CAD.