Introduction: We tested the hypothesis that low dose dobutamine stress echocardiography (LDDSE) combined with tissue Doppler imaging (TDI) can be used for the quantitative assessment of the content of viable myocardium.
Methods: Forty-one patients with coronary artery disease and left ventricular dysfunction (ejection fraction < or =40%), already scheduled for revascularisation, underwent echocardiographic assessment of viability at rest and during low-dose dobutamine infusion (2.5 microg/kg/min up to 10 micro/kg/min) at two time points, 2 days before and 3 months after revascularisation. Pulsed-wave TDI was performed at rest and during LDDSE; ejection (Ej), pre-ejection (pre-Ej) and diastolic velocities (Ea, Aa) were recorded at rest and at 10 microg/kg/min dobutamine infusion. Recovery of regional function was defined as improvement of one or more grades 3 months post-revascularisation.
Results: A total of 112 vessels were revascularised. Out of 492 segments, 274 segments were characterised as viable and the remaining 218 as non-viable, according to postoperative functional myocardial recovery. Conventional qualitative LDDSE showed a sensitivity of 78% and specificity of 85% in predicting myocardial recovery. Ej, pre-Ej and Ea velocities increased significantly during LDDSE, while Aa velocity did not change significantly. Using ROC curves, the optimal cut-off value for viability assessment was an increase of 0.5 cm/s in Ej during LDDSE (80% sensitivity and 88% specificity, area under the curve 0.801), 0.6 cm/s in pre-Ej (91% sensitivity and 90% specificity, area under the curve 0.890), and 0.44 cm/s in Ea velocity (80% sensitivity and 81% specificity, area under the curve 0.780).
Conclusions: Despite its technical limitations, the measurement of ejection and pre-ejection velocities during dobutamine stimulation appears to be an effective way of predicting myocardial segmental recovery following reperfusion.