Prognostic implications of evaluation of contractile reserve in akinetic and hypokinetic segments during low dose dobutamine echocardiography in patients with acute myocardial infarction

Background: Previous studies have reported the prognostic value of myocardi al viability (MV) detected using low-dose dobutamine echocardiography (DbE) . However, viability was frequently evaluated as improvement in regional wa ll motion score index, which includes increased function in hypokinetic seg ments, in which viable myocardium is necessarily present. It is not known w hether an evaluation focusing on akinetic segments, in which the possible p resence of viable myocardium is unknown, might have more prognostic value. The aim of this study was to compare the prognostic value of the improvemen t of myocardial function during dobutamine infusion in akinetic and hypokin etic regions in patients with acute myocardial infarction (AMI). Methods: 1 91 patients with uncomplicated AMI and at least one akinetic segment were r etrospectively selected from those consecutively examined at our echo-labor atory to evaluate MV using DbE. Myocardial viability was evaluated both as an increment in RWMSI (Delta RWMSI), which takes into consideration improve ment in both akinetic and hypokinetic regions, and as an improvement of fun ction in akinetic (Delta akinetic) and hypokinetic (Delta hypokinetic), seg ments considered separately. Follow-up evaluation was performed at 30 +/- 1 3 months. Results: On the basis of the Delta RWMSI, 94/191 patients were ju dged to have myocardial viability, whereas considering myocardial viability in akinetic segments only, 72/191 patients showed viability. At follow-up 18 patients had died (six viable considering Delta RWMSL three viable consi dering Delta akinetic). The presence of a previous AMI, the site of AMI. RW MSI and the number of akinetic segments, and Delta RWMSI and Delta akinetic were related to mortality at univariate Cox analysis. At multivariate step wise Cox regression analysis Delta akinetic, but not Delta hypokinetic prov ed to be significantly related to mortality. The Kaplan-Meier survival curv es were no different in patients with or without viable myocardium evaluate d as Delta RWMSI, while they were significantly different considering patie nts with or without viability in akinetic segments (P = 0.04). Conclusion: In conclusion our study confirms the prognostic importance of the evaluatio n of myocardial viability in infarcted patients. However, it points out tha t it is the presence of viability in akinetic segments that affects long-te rm survival in these patients. This supports the hypothesis that other mech anisms, above and beyond the effect on regional wall motion, are involved i n the beneficial effects of myocardial viability. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.