Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography

Abstract

Patients undergoing dobutamine stress echocardiography often take β antagonists which limit heart rate response and sensitivity in the test for detection of coronary artery disease. The aim of this study was to assess the effect of the addition of atropine to dobutamine stress echocardiography on clinical, electrocardiographic and echocardiographic outcomes. Dobutamine stress echocardiography was performed starting at and increasing every 3 minutes with 10 μg/kg/min to a maximum of 40 μg/kg/min (stage 4), which was continued for 6 minutes. In patients not achieving 85% predicted maximal exercise heart rate and in whom the test was not judged positive on echocardiographic or electrocardiographic criteria, atropine (0.25 mg intravenously, repeated up to a maximum of 1 mg if necessary) was added and dobutamine continued for up to a further 5 minutes, or until an adequate heart rate was achieved or the test was stopped because of chest pain or electrocardiographic changes. Of 80 consecutive patients undergoing dobutamine stress echocardiography within 2 weeks of coronary angiography, 49 required atropine (group A) and 31 required only dobutamine (group B). After dobutamine alone, heart rate (mean ± SD) was higher in group B than in group A: 129 ± 20 vs 90 ± 18 beats/min, p < 0.0001; but after the addition of atropine, heart rate in group A increased to 120 ± 20 beats/min. Overall sensitivity for the detection of coronary disease was 70%, 95% confidence interval (CI) 55 to 83%; after the addition of atropine, sensitivity for group A was 65%, 95% CI 45 to 81%; in group B, sensitivity was 81%, 95% CI 54 to 96%. Overall specificity for the detection of coronary disease was 88%, 95% CI 72 to 97%; specificity was 89%, 95% CI 65 to 99% after atropine in group A and 87%, 95% CI 60 to 98% in group B. The addition of atropine did not reduce specificity of the test. There were no severe complications and no difference between groups in the frequency of complications or the need to administer β blockers for relief of symptoms. The addition of atropine to dobutamine stress echocardiography in patients whose test results are negative and who do not achieve 85% predicted maximal heart rate during dobutamine alone increases the sensitivity of the test for detection of coronary artery disease without loss of specificity and without severe adverse effects.