Background : Stem cell therapy is reported to improve left ventricular (LV) systolic function in patients with myocardial infarction (MI). However, no data is available on the effect of stem cell therapy on the re-coordination of LV systolic contraction. We evaluated the role of the intracoronary infusion of peripheral blood stem cells in the fine-tuning of the LV myocardial systolic contraction pattern by using echocardiographic tissue synchronization imaging (TSI).
Methods and Results : Fifty patients with MI who underwent successful coronary artery stenting were randomly allocated to the cell infusion or the control group. Evaluations were performed with echocardiographic TSI 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. There were no significant differences in baseline characteristics between the two groups. At 6 36.4msec,months, greater improvements in Ts-SD (��Ts-SD: -37.7짹42.4 vs. 8.3짹 p<0.001) and LVEF (��LVEF: 5.0짹7.5 vs. 1.1짹5.7%, p=0.016) relative to the corresponding baseline values were observed in the cell infusion group than in the control group. By multivariate analysis, ��Ts-SD emerged as the only independent determinant of LVEF improvement(p=0.012) and cell infusion as the only independent determinant of ��Ts-SD improvement(p=0.008). Maximal exercise capacity measured by symptom-limited treadmill testing correlated well with Ts-SD (p=0.001, r=-0.48) but not with LVEF at 6 months of follow-up.
Conclusions : Stem cell therapy had a favorable effect on the restoration of LV synchronous contraction in patients with MI. The restoration of LV synchronicity could be a potential mechanism for improvement in LV systolic function and exercise capacity in patients who have undergone stem cell therapy.