Objectives. We sought to compare the magnitude of ischemia precipitated by both treadmill exercise and dobutamine stress echocardiography.
Background. Although it is alleged that dobutamine stress produces ischemia similar in degree and extent to that produced during treadmill exercise, a direct comparison with treadmill exercise, the most common form of exercise, has not been performed.
Methods. Eighty-five consecutive patients with known coronary artery disease underwent both stress tests on the same day, in random order.
Results. Sixty-two patients (73%) had positive results on exercise echocardiography compared with 53 (62%) who had positive results on dobutamine stress (p = NS). Of the 53 patients with positive dobutamine test results, wall motion abnormalities appeared after the addition of atropine in 35 patients (66%). During dobutamine infusion, 22 patients (26%) had a hypotensive response that was reversed in 16 by prompt administration of atropine. At peak dobutamine–atropine stress, heart rate was higher than that at peak exercise (p < 0.001), whereas systolic blood pressure and rate–pressure product were higher at peak exercise than at peak dobutamine–atropine stress (p = 0.0001). In the 53 patients with positive results on both tests, peak wall motion score index was greater with treadmill exercise than with dobutamine–atropine infusion ([mean ± SD] 1.73 ± 0.45 vs. 1.57 ± 0.44, p < 0.001).
Conclusions. Echocardiography immediately after treadmill exercise induces a greater ischemic burden than dobutamine–atropine infusion. In the clinical setting, exercise echocardiography should therefore be chosen over dobutamine echocardiography for diagnosing ischemia, when possible. When dobutamine echocardiography is used as an alternative modality, maximal heart rate should always be achieved by the addition of atropine.
