Background: Investigations of a strain index for the viability of ischemic myocardium with acute myocardial infarction (AMI) have been challenging. Therefore, the aim of this study was to evaluate patients with AMI to determine an optimal strain index for predicting the viability of ischemic myocardium.
Methods and results: A total of 57 patients with AMI were assessed according to two-dimensional (2D) speckle tracking imaging strain and strain rate (SR), measured during the acute phase before urgent revascularization and at a 1-year follow-up postrevascularization. During the acute phase, all the myocardial segments were classified according to the acute end-systolic strain (Ses) values as normal (Ses ≤ -13%), hypocontractile (-13% < Ses ≤ -7%), or having a severe contractile abnormality (Ses > -7%). At the 1-year follow-up, we reassessed the recovery of the segments with a severe contractile abnormality. The viability of these segments was defined as an improved Ses (≤ -7%) at follow-up postrevascularization. The Ses values, postsystolic strain index (PSI), and SR values were significantly better in the viable segments than in the nonviable segments at both the acute phase and at follow-up (P < 0.001). The initial postsystolic to systolic SR ratio (SRps/SRs) had the best area under the curve (AUC = 0.897). In addition, a cutoff value of 0.6 predicted recovery from a severe contractile abnormality with a sensitivity of 75% and a specificity of 88%.
Conclusions: The initial SRps/SRs ratio identified the viability of ischemic myocardium with AMI; therefore, this novel index may be clinically useful in the treatment of patients with AMI.
Keywords: acute myocardial infarction; echocardiography; strain; strain rate imaging; viability.
© 2013, Wiley Periodicals, Inc.