Detecting Viable Myocardium By Low-dose Dobutamine Echocardiography Predicts Improvement Of Left Ventricular Function After Coronary Intervention In The Patients With Myocardial Infarction

Objective: 1. To study the value of low-dose dobutamine echocardiography (LDDE) in detection of viable myocardium; 2. To predict improvement of left ventricular function after coronary intervention by detecting the segment numbers of viable myocardium; 3. To assess the time course of functional recovery after coronary intervention in the patients with myocardial infarction and left ventricular dysfunction.Methods: Thirty patients (28 men, 2 women) with myocardial infarction (left ventricular ejection fraction, LVEF<50%) were investigated. Viable myocardium was detected by LDDE before coronary intervention. The infusing dose of Dobutamine starts with 5ug.kg-1.min-1 for 5 minutes, then increases up to 10ug-kg-1.min-1 for another 5 minutes. Two-dimensional echocardiography (2DE) images were collected at 3 time points-baseline, 5ug.kg-1.min-1 and 10ug.kg-1. Left ventricular regional wall motion andthickening in each segment were graded and scored using a 16-segment model and semiquantitative analysis method. The myocardium, whose abnormal motions at the baseline were improved after infusing dobutamine, were defined as viable myocardium. The segment numbers of viable myocardium were recorded. Wall motion score index (WMSI) and LVEF were evaluated with two-dimensional echocardiography (2DE) at 1week, 1 month, 3 month after intervention, respectively.Results: 1.Compared to wall motion recovery at 3 month after coronary intervention, for detecting the viable myocardium, the sensitivity and specificity of LDDE is 88% and 83% respectively. 2. In the patients with more than 4 viable segments (including 4 viable segments), both WMSI and LVEF improved significantly during 1 month and 3 month after coronary intervention (p<0.01). However, in the patients with less than 4 viable segments, WMSI and LVEF did not change significantly at 1 week, 1 month and 3 month after coronary intervention (p>0.05). 3. In the patients with more than 4 viable segments(including 4 viable segments), at 1 week after coronary intervention, WMSI and LVEF were not improved (p>0.05); if acute myocardial infarction (AMI), at 1 month, WMSI and LVEF started to be improved (p<0.01) and kept to be improved at 3 month (p<0.01); if old myocardial infarction (OMI), WMSI and LVEF were not improved significantly until 3 month after intervention.Conclusion: 1.LDDE is a safety and reliable way to detect the viable myocardium in the patients with myocardium infarction and left ventricular dysfunction. 2.1f the patients with more than 4 segments (including 4 segments) of viable myocardium detected by LDDE, their heart function will beimproved by coronary intervention. 3.The improvement started at 1 month and kept on at 3 month in the patients with AMI; Differently, the improvement in the patients with OMI started at 3 month. 4.The patients with myocardial infarction should receive coronary revascularization as soon as possible in order to recover heart function quickly.