Background: Dobutamine pharmodynamics require approximately 10 min to reach steady state. Despite this, standard dobutamine stress echo typically uses 3-min stages of advancing dobutamine doses because of safety concerns.
Hypothesis: In patients with a high pretest probability of coronary artery disease (CAD), a continuous infusion of high-dose dobutamine is a feasible and safe method for performing a dobutamine stress test.
Methods: Forty-seven consecutive patients (mean age 64 +/- 11 years) with 3.0 +/- 1.4 cardiac risk factors underwent dobutamine stress testing utilizing a single, high-dose (40 mcg/kg/min), continuous dobutamine infusion. The 40 mcg/kg/min infusion was continued for up to 10 min or until a test endpoint had been reached. If a test endpoint was not achieved, atropine (up to 1.0 mg) was added.
Results: Heart rate rose from 71 +/- 12 to 137 +/- 18 beats/min at peak (p<0.0001) with a concomitant change in systolic blood pressure (143 +/- 35 vs. 167 +/- 38 mmHg; p = 0.001) but no change in diastolic blood pressure (74 +/- 19 vs. 75 +/- 18 mmHg; p = NS). Target heart rate was achieved in 20 of 47 (43%) patients with accelerated dobutamine alone and in 34 of 47 (72%) with the addition of atropine. An average of 11.6 +/- 3.7 min was required to obtain target heart rate. Subjective sensations from the dobutamine occurred in 49% of patients (palpitations 21%, nausea 6%, chest pain 6%, headache 6%, dizziness 13%), mild arrhythmia in 48% of patients (ventricular premature beats 38%, supraventricular tachycardia 10%), and one patient had nonsustained ventricular tachycardia.
Conclusion: A single, high-dose (40 mcg/kg/min) dobutamine-atropine protocol provides an efficient means of performing dobutamine stress echocardiography with a similar symptom profile as conventional dobutamine infusion protocols in patients with a high pretest probability of CAD. Randomized, controlled studies will be necessary to assess the sensitivity and specificity of this accelerated dobutamine echo protocol.