DETECTION OF MYOCARDIAL VIABILITY USING DOBUTAMINE STRESS ECHOCARDIOGRAPHY AND MYOCARDIAL CONTRAST AFTER ACUTE MYOCARDIAL INFARCTION

Abstract

Background: Both low‐dose dobutamine stress echocardiography (LDDE) and myocardial contrast echocardiography (MCE) are capable of identifying myocardial viability by different means. However, it is not well known which of them is more accurate in the setting of AMI. Objective: We evaluated the diagnostic value of LDDE and MCE using second harmonic with and without intermittent imaging in the detection of myocardial viability after acute myocardial infarction (AMI) treated with successful thrombolysis. Methods: We studied 50 patients in the first week after AMI, at rest with LDDE, with and without MCE. We evaluated the recovery of left ventricular ejection fraction (LVEF) at rest by two‐dimensional echocardiography as well as by myocardial scintigraphy (Gated Spect), between the fourth and sixth month of follow‐up. According to an absolute 5% increase in LVEF measured by the two Gated Spect studies, pts were divided in group I, with functional recovery (19 patients) and group II, without functional recovery (31 patients). To analyze the contractility and myocardial perfusion, we used a left ventricular wall motion score index and myocardial perfusion score index at rest and during dobutamine. Myocardial viability was defined by LDDE as an improvement segmental wall motion at least one grade in two or more contiguous infarct zones segments at any stage of dobutamine infusion and by MCE as myocardial perfusion grade 1 or 2 at least in one infarct segment, at any stage of the study. Results: Group 1 had a total of 103 dysfunctioning infarct‐related segments. LDDE revealed the myocardial viability in 61 segments while MCE demonstrated perfusion grade 1 or 2 in 79 of them. In group 2, of 173 dysfunctioning infarct‐related segments, viable myocardium was detected in 23 segments by LDDE and 98 segments by MCE. Only two of 99 segments without viability showed recovery of function at follow‐up. The overall results patient by patient of LDDE in order to predict the LVEF recovery, sensitivity was 95%, specificity 87%, positive predictive value 82%, negative predictive value 96% and diagnostic accuracy 90% (κ= 0.794). When we analyzed the overall results patient by patient of MCE, we demonstrated a sensitivity of 95%, specificity of 52%, positive predictive value of 54%, negative predictive value of 94%, and diagnostic accuracy of 68% (κ= 0.479). Conclusion: The detection of contractile reserve by the use of LDDE was accurate in predicting LVFR in patients after AMI treated with successful thrombolytic therapy, while MCE demonstrated high negative predictive value.