Usefulness of Dobutamine Stress Echocardiography for Identification of Viable Myocardium in Acute Myocardial Infarction

ABSTRACT

BACKGROUND: In patients with acute myocardial infarction(MI), dysfunctional myocardium at rest after successful reperfusion may represent either necrotic or viable myocardium. And the latter can be recovered contractility after revascularization or medication. OBJECTIVE: To evaluate the efFectiveness of the dobutamine stress echocardiography(DSE) for identifying viable but dysfunctional myocardium in acute MI before revascularization. METHOD: Twelve patients with acute MI after thrombolytic therapy underwent Tc-99m-tetrofosmin dipyridamole myocardial SPECT(Single Photon Emission Computed Tomography) and DSE before coronary angiography in 7~12 hospital days, and they were followed up for recovery of contractile reserve by two-dimensional echocardiography after revascularization procedure or medication. Regional wall motion abnorrnality was scored from l(normal) to 4(dyskinesia). Dobutamine responsiveness was defined as irnprovement or aggravation of regional wall motion in dyssynergic segment during any stage of dobutamine infusion. Reversible ischemia by SPECT was defined as increased perfusion defect after dipyridamole and interpreted by radiologist. Dobutamine responsiveness on DSE and reversible ischemia on myocardial SPECT were matched and compared each other. RESULTS: Of 69 dyssynergic segments, 38(55%) recovered contractility during follow up echocardiography after revascularization or medication. In 30(79%, sensitivity) of these latter segments, regional wall motion had changed during dobutamine. However, 31(45%) did not recovered contractility and 25(81%, specificity) of thern had not changed during dobutamine. Of 36 dobutamine responsive dyssynergic segments, 30(83%, positive predictive accuracy) had recorved contractility. In 25(76%, negative predictive accuracy) of 33 dobutamine non-responsive segments had not recovered contractility. Reversible ischemia on myocardial SPECT showed less sensitive(67%) and specific(56%) for detection of potentially recoverable myocardium than DSE. And positive(68%) and negative predictive accuracy(56%) also showed significantly lower than DSE. CONCLUSION: DSE can identify dyssynergic but recoverable myocardial segement for risk stratification before intervention in acute MI. Dobutamine responsiveness of dyssynergic segment is superior to reversible ischemia on myocardial SPECT for prediction of wall motion improvement after MI irrespective of intervention or medical therapy.