LOW-DOSE DOBUTAMINE ECHOCARDIOGRAPHY DETECTS REVERSIBLE DYSFUNCTION AFTER THROMBOLYTIC THERAPY OF ACUTE MYOCARDIAL-INFARCTION

Background. Dysfunction after thrombolytic therapy of acute myocardial infarction (MI) may be reversible. Early after myocardial infarction, both reversible and irreversible injury may be manifested by regional wall motion abnormalities. Improved wall thickening during dobutamine infusion (dobutamine-responsive wall motion) may accurately identify reversibly injured segments. Methods and Results. To determine whether dobutamine-responsive wall motion accurately detects reversible postischemic dysfunction irrespective of infarct location, multistage (baseline, 4 and 12 mug . kg-1 . min-1, and peak) dobutamine echocardiography (DE) was performed within 7 days of thrombolytic therapy. Resting echocardiography was repeated greater-than-or-equal-to 4 weeks after MI, and reversible dysfunction was defined as improved wall motion. The accuracy of dobutamine-responsive wall motion was compared with that of signs of early reperfusion, non-Q-wave MI, and peak creatine kinase (CK). Sixty-three patients underwent DE without complications. Follow-up echocardiograms were done in 51 (81%) of these patients, and wall motion improved in 22 (41%). Dobutamine-responsive wall motion during all stages of DE was very specific for reversible dysfunction (90% to 93%) but sensitive (86%) only when hemodynamics were not altered (low dose, 4 mug . kg-1 - min-1 ). Non-Q-wave MI and a low peak CK (<1000 IU/mL) were also specific (89% to 93%) but less sensitive (64% [P=.16] and 55% [P<.05], respectively). Signs of early reperfusion did not identify postischemic dysfunction. Low-dose dobutamine-responsive wall motion and non-Q-wave MI independently identified reversible dysfunction, but only dobutamine-responsive wall motion was sensitive in all infarct locations. Non-Q-wave MI was sensitive only in anterior infarction. Conclusions. Multistage dobutamine echocardiography can be performed safely early after thrombolytic therapy. Low-dose dobutamine-responsive wall motion accurately detected reversible dysfunction in all infarct locations. Dobutamine-responsive wall motion and non-Q-wave infarction may be very useful for accurately identifying reversible dysfunction early after thrombolytic therapy for acute MI.