Dobutamine echocardiography for the identification of viable myocardium in patients with left ventricular dysfunction undergoing coronary surgery

In order to evaluate dobutamine echocardiography for the detection of viable myocardium in patients undergoing coronary artery bypass grafting, we scheduled 10 patients (males, mean age 59.5 ± 7.4 years, range 40-72) with severe ischemic left ventricular dysfunction (mean ejection fraction 29.1 ± 4.4%, range 19-40%). All patients underwent preoperative dobutamine echocardiography: dobutamine infusion was administered at a 5 μg/Kg/min dose for 5 min (first step), followed by a 10 μg/Kg/min dose for further 5 min (second step). Continuous electrocardiographic monitoring was performed. Echocardiographic images were digitized on-line. Regional wall motion index was scored on a 16 left ventricular segment score system (160 total segments). During dobutamine echocardiography test neither signs or symptoms of myocardial ischemia nor arrhythmia occurred. Mean left ventricular ejection fraction increased from 29.1 ± 4.4 to 40.5 ± 8.8% (p < 0.001) and mean regional wall motion index decreased from 1.44 ± 0.35 to 1.20 ± 0.40 (p < 0.001) at the end of the dobutamine infusion. Intraoperative myocardial protection was performed according to Buckberg protocol. Death or perioperative myocardial infarction were not recorded. Clinical evaluation and two-dimensional echocardiography were performed 3 months later. All patients improved their clinical status (at least one NYHA class) and no signs of recurrent ischemia were recorded. Among total 160 left ventricular segments, 61 were excluded from the analysis: 43 because normokinetic at rest and 18 because not revascularized at operation. During dobutamine echocardiography wall motion remained unchanged in 69/99 segments, thus they were considered not viable: in 60/69 of these segments wall motion remained unchanged after coronary surgery (specificity 79%). During dobutamine echocardiography wall motion impairment decreased or reversed in 30/99 segments, thus they were considered viable: in 14/30 of these segments wall motion improved after coronary surgery (sensitivity 61%). In conclusion, dobutamine echocardiography seems to be a safe, reliable and low-cost test in surgical decision-making for patients with severe ischemic left ventricular dysfunction.