Restoration of left ventricular synchronous contraction after acute myocardial infarction by stem cell therapy: new insights into the therapeutic implication of stem cell therapy for acute myocardial infarction

Objective: To evaluate the effects of stem cell therapy on restoration of the left ventricular (LV) synchronous contraction in patients with acute myocardial infarction (AMI). Methods: 40 patients with AMI who underwent successful coronary revascularisation were randomly allocated to the cell infusion or the control group. Evaluations were performed with echocardiographic tissue synchronisation imaging to determine LV dyssynchrony and with cardiac magnetic resonance imaging to estimate LV ejection fraction (LVEF) at baseline and at 6 months. To quantify the severity of systolic LV dyssynchrony, the standard deviations of time to peak systolic velocity of the 12 LV segments (Ts-SD) were calculated. Results: At 6 months, greater improvements of Ts-SD (Delta Ts-SD: -45.0 (40.2) vs 5.0 (39.9) ms, p < 0.001) and LVEF (Delta LVEF: 6.8% (9.1%) vs -0.2% (6.9%), p = 0.015) relative to the corresponding baseline values were observed in the cell infusion group than in the control group. By multivariate analysis, Delta Ts-SD and baseline LVEF emerged as the independent determinants of LVEF improvement and cell infusion, and baseline Ts-SD as the determinant of Delta Ts-SD improvement. Maximal exercise capacity measured by symptom-limited treadmill testing correlated well with Ts-SD but not with LVEF at 6 months of follow-up. Conclusion: Stem cell therapy had a favourable effect on the restoration of LV synchronous contraction in patients with AMI.