Dobutamine Echocardiography in the Prediction of Left Ventricular Remodeling after Acute Myocardial Infarction

ABSTRACT

BACKGROUND: Left ventricular remodeling after acute myocardial infarction has been identified as an important prognostic factor because it leads to ventricular enlargement, ventricular aneurysm, and increased mortality. However predictors of left ventricular remodeling are not clearly defined. This study was perforrned to evaluate the efficacy of dobutamine echocardiography in the prediction of left ventricular remodeling in patients with acute myocardial infarction. METHODS: Forty-five patients(39 males, age 56.9+/-10.2 years) with acute myocardial infarction(AMI) and patent infarct-related artery(no significant narrowing with/without revascularization) underwent dobutamine echocardiography at 2 7 days after AMI. The stages of dobutamine infusion were baseline, 5, 10, 20ug/kg/min, and images at each stage were directly compared and analyzed with the use of 16-segment model(by American Society of Echocardiography) and scoring system(1 normal, 2 mild to moderate hypokinesia, 3 severe hypokinesia, 4 akinesia, 5 dyskinesia). The viability of infarct zone was defined as improvement of wall motion score in more than 2 contiguous segments during dobutamine infusion in areas of resting asynergy. Coronary angiography was performed at 7~10 days after AMI and revascularization of infarct-related artery was done, if severe stenosis was present. Follow-up(F/ U) echocardiography was performed more than 3 months after AMI. We have measured left ventricular end-diastolic and end-systolic volume at baseline, dobutamine(peak dose) and follow-up echocardiography by modified Simpsons method. RESULTS: 1) Dobutamine echocardiography was performed at 5.5+3.9 days after acute myocardial infarction, and follow-up echocardiography was performed at 7.5+3.4 months after dobutamine echocardiography. 2) We assessed left ventricular end-diastolic volume(LVEDV) at follow-up echocardiography compared to LVEDV at baseline echocardiography, and patients were divided into 2 groups. Group 1(n=14) with increase in LVEDV during F/U period(mean change 13.9+14.2ml); Group 2(n=31) with no increase in LVEDV volume during F/U period(mean change 27.4+22.1). Between two groups, clinical parameters such as age, sex, incidence of anterior myocardial infarction, incidence of non-Q myocardial infarction, peak CK, peak CKMB, pre-infarction angina, incidence of reperfusion therapy, follow-up duration, were not significantly different. 3) Between group 1 and group 2, there were no singnificant differences in baseline echocardiographic parameters such as ejection fraction, wall motion score index, LVEDV, LV enddiastolic dimension. 4) In group 1, the incidence of patients with infarct zone viability assessed by dobutamine echocardiography was significantly snialler than the one in group 2(5 of 14 and 21 of 31, respectively, p <0.05). 5) Beween group 1 and group 2, the change of LVEDV at dobutamine echocardiography compared to LVEDV at baseline echocardiography was significantly different( -1.3+/-17.7 and -17.1+/-26.2, respectively, p<0.05). 6) Linear regression analysis indicated that the change of LVEDV during follow-up period was predicted by the change of LVEDV during dobutamine echocardiography. LVEDV(F/U) LVEDV(baseline) = 0.726[LVEDV(dobutamine) LVEDV(baseline) ] 5.648(r=0.65, p<0.05) CONCLUSION: The viability of infarct zone assessed by dobutamine echocardiography was predictive of left ventricular remodeling at F/U of acute myocardial infarction and the change in LVEDV during dobutamine echocardiography correlated with the change in LVEDV at follow-up of acute myocardial infarction. Dobutamine echocardiography can be an useful tool for the prediction of LV remodeling after acute myocardial infarction.