2007 Volume 5 Issue 3 Pages 65-71
Dobutamine stress echocardiography (DSE) is widely used to evaluate myocardial ischemia or to clarify the differential diagnosis of chest pain. DSE is often complicated by insufficient heart rate response, hypotension or other adverse events. We report the results of the assessment of a modified protocol for DSE, in which 0.5mg of intravenous atropine administration was followed by dobutamine (DOB) infusion at 10 μg/kg/min. Three hundred twenty-two consecutive patients, 172 patients studied with the modified protocol and 150 controls undergoing conventional DSE, were compared. The percentage of patients attaining target heart rate (THR) via the modified protocol was significantly increased (65% vs. 35%, P<0.0001). The percentage of patients developing hypotension (defined as a decrease in systolic blood pressure (SBP) >25mmHg) was significantly decreased (<1% vs. 19%, P<0.0001). Fewer patients required the maximum dose (40 μg/kg/min) of DOB infusion. Peak heart rate (peak HR), peak HR:THR ratio, peak SBP, and the peak rate-pressure product were higher with the modified protocol, as compared to the conventional protocol (P<0.0001). DOB requirements were significantly reduced in patients not receiving βblockers (P<0.0001), but not in patients on βblockers (P=NS). The prevalence of arrhythmias, SBP>250mmHg, de novo intra-ventricular gradient development (>100mmHg) and intolerable symptoms did not differ between the groups. Coronary angiography was performed in 80 patients including in 45 patients with the conventional protocol and 35 patients with the modified protocol. No significant difference in sensitivity, specificity, accuracy, positive predictive value and negative predictive value of the two protocols was observed. These results indicate that the modified protocol improves attainment of THR and prevents hypotension during DSE. Serious adverse events were not increased.