DOBUTAMINE ECHOCARDIOGRAPHY PREDICTS IMPROVEMENT OF HYPOPERFUSED DYSFUNCTIONAL MYOCARDIUM AFTER REVASCULARIZATION IN PATIENTS WITH CORONARY-ARTERY DISEASE

Background In patients with coronary artery disease, dysfunctional hypoperfused myocardium at rest may represent either necrotic or viable hibernating myocardium. The accuracy of inotropic stimulation in identifying hypoperfused, reversibly dysfunctional myocardium has not been extensively investigated. Methods and Results Eighteen patients with stable chronic coronary artery disease underwent, while off drugs, quantitative Tl-201 single-photon emission computed tomography after rest injection (2 to 3 mCi), two-dimensional echocardiography at rest and during dobutamine (5 to 10 mu g/kg per minute IV), and radionuclide angiography. Single-photon emission computed tomography and echocardiography at rest were repeated 34+/-10 days after coronary revascularization, and radionuclide angiography was repeated 45+/-13 days after revascularization. Resting hypoperfusion was defined as Tl-201 uptake <80% of maximal activity. Systolic function was scored from 1 (normal) to 4 (dyskinesia), and functional improvement was defined as a score change >1 grade. Of 79 dysfunctional hypoperfused segments, 48 (61%) improved function after revascularization. In 42 (88%) of these latter segments, function had improved during dobutamine. Conversely, systolic function after revascularization did not improve in 31 segments, and in 27 (87%), it had not improved during dobutamine. Functional improvement after revascularization was observed in 42 (91%) of 46 segments manifesting an improvement during dobutamine as opposed to 6 (18%) of 33 segments that did not improve during dobutamine. Resting Tl-201 uptake (% of maximal activity) before revascularization (65+/-9%) significantly increased at follow-up in segments where function improved (70+/-12%, P<.005), whereas it did not change significantly in segments with unchanged systolic function after revascularization (from 57+/-13% to 60+/-17%, P=NS). In 10 patients with prerevascularization ejection fraction <45%, left ventricular ejection fraction significantly increased from 36+/-7% before revascularization to 42+/-7% at follow-up (P<.05). Conclusions Inotropic stimulation using dobutamine echocardiography identifies hypoperfused reversibly dysfunctional myocardium. Functional improvement during dobutamine is highly predictive of improvement after revascularization.