Comparison of safety and efficacy of the early injection of atropine during dobutamine stress echocardiography with the conventional protocol

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Although dobutamine–atropine stress echocardiography (DASE) is an established method for evaluating patients who have coronary artery disease (CAD), it can increase test duration and a patient's exposure to large doses of dobutamine. New protocols, including the early injection of atropine during dobutamine stress echocardiography (EA-DSE), have been proposed to decrease test duration. This study compared the safety, efficacy, and accuracy of EA-DSE with those of DASE. We retrospectively evaluated 3,163 patients who underwent DASE and 1,664 patients who underwent EA-DSE over a period of 12 years. In EA-DSE, atropine at a dose ≤2 mg was started with 20 μg/kg/min of dobutamine if heart rate was <100 beats/min. Diagnostic accuracy for detecting CAD (>50% stenosis) was assessed in patients who underwent quantitative angiography ≤3 months of stress testing. The dobutamine dose used in EA-DSE was smaller than that used in DASE (31 ± 6 vs 36 ± 6 μg/kg/min, p <0.0001), although the atropine dose was larger (0.8 ± 0.5 vs 0.5 ± 0.25 mg, p <0.0001). EA-DSE resulted in a significantly shorter duration of dobutamine infusion (12.4 ± 2.0 vs 14.6 ± 2.5 minutes, p <0.0001), more diagnostic studies (88% vs 81%, p <0.0001), and a lower incidence of minor adverse effects than did DASE. The rate of major adverse effects was similar in the 2 protocols. Sensitivities, specificities, positive predictive values, negative predictive values, and accuracies for detecting CAD were 84%, 90%, 93%, 76%, and 86% for EA-DSE and 86%, 78%, 84%, 79%, and 82% for DASE, respectively (p = NS). Therefore, EA-DSE is a safe and effective alternative to DASE and had a similar accuracy for the detection of CAD.

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Patients

We retrospectively analyzed a large databank that contained information about patients who had known or suspected CAD and were referred for dobutamine stress echocardiography. From July 1991 to December 1999, 3,369 patients underwent DASE. From January 2000 to June 2003, 1,984 patients underwent EA-DSE. Exclusion criteria were contraindications to any drug used in the study protocol,2 age <18 years, and submaximal tests performed for evaluation of myocardial viability. Cardioactive medications

Dobutamine and atropine doses

The dose of dobutamine used for EA-DSE was significantly smaller than that used for DASE (31 ± 6 vs 36 ± 6 μg/kg/min, respectively; p <0.0001). For EA-DSE, using 40 μg/kg/min of dobutamine was required to reach the study end points in only 328 patients (20%). In contrast, for DASE, 2,179 patients (69%) required this dose (p <0.0001 vs EA-DSE). The proportion of patients who received atropine during stress testing was larger for EA-DSE than for DASE (83% vs 33%, p <0.01), as was the mean dose of

Discussion

In the present study, we describe a comparison between EA-DASE and DASE performed in a systematic way in a large number of patients (4,827 examinations). EA-DSE required smaller doses of dobutamine and resulted in lower rates of minor adverse effects compared with DASE. Importantly, for EA-DSE, the incidence of major adverse effects remained low, similar to those reported previously.1, 16, 17 Conventional administration of atropine at peak doses of dobutamine may lead to rapid increases in

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This study was supported by institutional grants from the Heart Institute, University of São Paulo Medical School, São Paulo, Brazil.

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