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

Background In patients with coronary artery disease, dysfunctional hyp operfused myocardium at rest may represent either necrotic or viable h ibernating myocardium. The accuracy of inotropic stimulation in identi fying hypoperfused, reversibly dysfunctional myocardium has not been e xtensively investigated. Methods and Results Eighteen patients with st able chronic coronary artery disease underwent, while off drugs, quant itative Tl-201 single-photon emission computed tomography after rest i njection (2 to 3 mCi), two-dimensional echocardiography at rest and du ring dobutamine (5 to 10 mu g/kg per minute IV), and radionuclide angi ography. Single-photon emission computed tomography and echocardiograp hy at rest were repeated 34+/-10 days after coronary revascularization , and radionuclide angiography was repeated 45+/-13 days after revascu larization. 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 segment s, function had improved during dobutamine. Conversely, systolic funct ion after revascularization did not improve in 31 segments, and in 27 (87%), it had not improved during dobutamine. Functional improvement a fter revascularization was observed in 42 (91%) of 46 segments manifes ting an improvement during dobutamine as opposed to 6 (18%) of 33 segm ents 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 unch anged systolic function after revascularization (from 57+/-13% to 60+/ -17%, P=NS). In 10 patients with prerevascularization ejection fractio n <45%, left ventricular ejection fraction significantly increased fro m 36+/-7% before revascularization to 42+/-7% at follow-up (P<.05). Co nclusions Inotropic stimulation using dobutamine echocardiography iden tifies hypoperfused reversibly dysfunctional myocardium. Functional im provement during dobutamine is highly predictive of improvement after revascularization.