REPRODUCIBILITY OF DOBUTAMINE DIGITAL STRESS ECHOCARDIOGRAPHY

The aim of this study was to investigate the temporal variability and interobserver agreement of dobutamine digital stress echocardiography. We performed two dobutamine stress echocardiographic studies (dobutam ine up to 40 mu g/kg/min and atropine up to 1 mg) in 15 patients with previous myocardial infarction at a mean of 19 days apart. Two observe rs assessed the wall motion using a six-point score in a 16-segment mo del and calculated the wall motion score index at rest and at peak str ess by using a quad screen display. Analysis of the wall motion was pe rformed separately on the day after each dobutamine stress test (analy sis A), and all images from the two serial studies in the same patient were simultaneously retrieved and compared side-by-side in the same v iew (analysis B). The mean values of heart rate and blood pressure wer e comparable for each stage in the two studies except for the heart ra te at rest. Regarding the presence and absence of positive findings of dobutamine stress echocardiography, interobserver agreement was 93% ( 70% to 99% with 95% confidence limits, kappa value 0.86) in the patien ts and 93% (70% to 99% with 95% confidence limits, kappa value 0.80) i n the three major vascular regions with the use of analysis A. These v alues did not improve with the use of analysis B. The agreement of the temporal variability was 93% (70% to 99% with 95% confidence limits, kappa value 0.86) in the patients and 84% (71% to 92% with 95% confide nce limits, kappa value 0.66) in the vascular regions with the use of analysis A. These values further improved with the use of analysis B. With the comparison of the wall motion score index, interobserver vari ability showed a correlation coefficient of 0.88 at rest and 0.90 at p eak stress with analysis A and 0.78 and 0.82, respectively, with analy sis B. Corresponding analysis of temporal variability showed correlati on coefficients of 0.99 at rest and 0.99 at peak stress when both anal yses were used. Although dobutamine digital stress echocardiography ha s good reproducibility and negligible interobserver variability, even if the digital quad screen format is used, it requires strict standard ization of the reading criteria and the objective measurements of wall motion in the expansion of this test to the evaluation of the changes in left ventricular function during more than two serial studies in t he same patient.