Extent and severity of test positivity during dobutamine stress echocardiography. Influence on the predictive value...

Recent studies have evaluated the diagnostic accuracy and predictive value of dobutamine echocardiography without considering the additional information implied by the magnitude of induced wall motion abnormalities. We sought to evaluate the positive predictive value of dobutamine echocardiography for coronary artery disease from the extent and severity of the induced wall motion abnormality. In addition, we intended to determine factors associated with false-negative dobutamine echocardiography.

Two hundred and eighty-three consecutive patients with suspected coronary artery disease underwent dobutamine echocardiography (up to 40 microg x kg(-1) x min(-1)+atropine up to 1 mg) and coronary angiography. The number of segments and the degree of deterioration were used to describe the extent and severity of induced wall motion abnormality. Analysis of clinical, procedural and echocardiographic variables was performed to determine factors associated with false-negative results. The positive predictive value of dobutamine echocardiography increased from 85% to 90%, 94% and 94% with deterioration of wall motion by one grade in >/=1, >/=2, >/=3 and >/=4 segments, respectively (P<0.05). Deterioration of wall motion by two grades in one segment had a positive predictive value of 96% as compared to 85% for deterioration by only one grade in one segment (P<0.05). Patients with false-negative test results received atropine more frequently (28% vs 13%, odds ration [OR]=3.87, 95% confidence interval [CI]=1.54-9.75, P=0.028) than patients with a correct positive result. However, angina (15 vs 37%, OR=0.26, 95% CI=0.09-0.71, P=0.010), ECG changes during dobutamine stress (15% vs 35%, OR=0.49, 95% CI 0.19-1.25, P=0.014) and high image quality (OR 1.59, 95% CI 1.07-2.37, P=0.015) were less frequent. The sensitivity of dobutamine echocardiography increased from 67% to 71% and 86% (P<0.05) with increasing achieved maximal heart rate (<75%, 75-85% and >85% of maximal heart rate).

The positive predictive value of dobutamine echocardiography increases significantly as the extent and severity of induced wall motion abnormality increases. Thus, the degree of test positivity should be reported in clinical practice. Despite high pharmacological drug doses, the haemodynamic response may still be insufficient in some patients to induce myocardial ischaemia, resulting in false-negative dobutamine echo tests. To maximize the sensitivity of dobutamine echocardiography, the highest haemodynamic stress level, with a heart rate above 85% of the predicted heart rate, should be reached.