Q. Define Accuracy of Stress Echocardiography?
The accuracy of stress echo tests for the detection of coronary artery disease is expressed as the sensitivity and specificity of the technique for the detection of angiographically demonstrated stenoses. In significant studies of exercise echocardiography (> 100 patients), the sensitivity and specificity range from 74-97 per cent and 64-86 per cent, respectively. Higher sensitivity may be obtained with bicycle exercise (as there is no loss of ischaemia in the post-stress period), but this is at the cost of some impairment in specificity. Comparisons with quantitative angiography have shown stenosis diameters of 0.7-1.0 mm to be associated with ischaemia.
Significant studies (> 100 patients) of dobutamine stress echocardiography show a range for sensitivity of between 61-95 per cent, while that for specificity ranged from 51-95 per cent.
The addition of atropine augments sensitivity. Dobutamine echocardiography is a more sensitive marker of ischaemia in lesions involving larger (> 2.6 mm diameter) vessels than smaller vessels.
The quantitative angiography parameters associated with ischaemia are a lumen diameter of < 1 mm diameter, per cent diameter stenosis of 52 per cent, and per cent area stenosis of 75 per cent, of which the minimal lumen diameter is most predictive of an abnormal dobutamine stress test.
The sensitivity and specificity of dipyridamole and adenosine stress echocardiography for the detection of coronary artery disease range from 61-81per cent and 90-94 per cent, respectively.
However, single vessel disease is more difficult to detect using this technique.