Cost-effectiveness and accuracy of exercise stress echocardiography in the non-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 scintigraphy (ETS) was developed to overcome the known limitations of ECG stress 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) of ESE in a group of patients referred for ETS imaging and compare the relative costs of each technique.

METHODS: One hundred and fifteen patients referred for ETS consented to a simultaneous 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 study population and 57 of the 59 patients who underwent coronary angiography). Of the 59 patients undergoing coronary angiography, the sensitivity of ESE and ETS were not significantly different (84.1% versus 91.3% respectively). 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 accuracy was also closely similar (86.0% versus 84.7% respectively) and therefore also not significantly different. By contrast, agreement with coronary angiography as measured by the kappa statistic (kappa +/- 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-effective imaging modality for the detection and localisation of CAD.