Serial changes in response of hibernating myocardium to inotropic stimulation after revascularization: a dobutamine echocardiographic study.

Objectives: We sought to evaluate the serial changes in the response of the hibernating myocardium to dobutamine stimulation after revascularization.

Background: An improvement in myocardial contraction during dobutamine stress echocardiography (DSE), particularly a biphasic response, predicts recovery of rest function. However, little is known about the changes in the response of the myocardium to dobutamine after revascularization.

Methods: Thirty-four patients with stable coronary artery disease and regional left ventricular dysfunction underwent DSE before, early (within 1 week) and late (>6 weeks) after coronary angioplasty. Dobutamine was given in incremental doses from 2.5 to 40 microg/kg body weight per min.

Results: Of 180 revascularized segments with severe rest dysfunction, recovery of rest function was seen in 56 segments (31%) late after angioplasty, 80% of which had early recovery. Ventricular function during DSE was similar early and late after revascularization. Patients who showed a biphasic response to DSE before revascularization (n = 12) had the most improvement in function at rest (mean [+/-SD] wall motion score index [WMSI] 1.98 +/- 0.75 vs. 1.35 +/- 0.54, p < 0.05) and during DSE (2.11 +/- 0.67 vs. 1.21 +/- 0.41, p < 0.05) late after revascularization. Patients with sustained improvement during DSE before revascularization had no significant change in wall motion during DSE after angioplasty. However, patients without improvement in function at low dose DSE, who demonstrated worsening of function at a high dose, had significant augmentation in wall motion during DSE after revascularization (WMSI 2.16 +/- 0.50 vs. 1.60 +/- 0.57, p < 0.05). Patients who had no recovery of rest function had significant improvement in wall motion response to DSE, particularly when ischemia was inducible before revascularization.

Conclusions: In myocardial hibernation, the majority of recovery of rest function occurs early after revascularization. Although patients who recover rest function show the most marked improvement in wall motion during DSE, those without recovery of rest function also have improved function during DSE, particularly when there is evidence of ischemia before revascularization.