Abstract 2718: Restoration of Synchronicity of the Left Ventricular Myocardial Contraction with Stem Cell Therapy: New Insights into the Therapeutic Implication of Stem Cell Therapy in Myocardial Infarction
Background: Stem cell therapy is reported to improve the left ventricular (LV) systolic function in patients with myocardial infarction(MI). However, there is a paucity of data on the effect of stem cell therapy on recoordination of the LV systolic contraction. To resolve this issue, we evaluated the role of intracoronary infusion of peripheral blood stem cell (PBSC) in fine-tuning LV myocardial systolic contraction pattern using a novel echocardiographic technique of tissue synchronization imaging(TSI).
Methods and Results: Fifty patients with MI who underwent coronary artery stenting were consecutively recruited and then randomly allocated into 2 groups. Forty seven patients were finally analyzed(cell infusion(n=25) vs. control(n=22)). Both echocardiography equiped with TSI and cardiac magnetic resonance imaging for LV ejection fraction(LVEF) measurement were performed at baseline and at 6 month after enrollment. For quantification of the severity of systolic LV dyssynchrony, the standard deviation of the time to peak systolic velocity(Ts-SD) of the 12 LV segments was calculated. Symptom limited exercise treadmill test was performed at 6 month to assess patients’ functional capacity. There were no differences in baseline characteristics between the 2 groups. At 6 month, Ts-SD was markedly decreased in the cell infusion vs. control group (−37.7±42.4 vs. 8.±336.4msec, p<0.001). ΔLVEF increased in the cell infusion group compared to the control group(5.6±7.1% vs. 0.9±5.5%, p=0.016). ΔTs-SD correlated moderately with ΔLVEF(r=– 0.54, p<0.001). On multivariate analysis, ΔTs-SD(p=0.012) emerged as an only independent determinant of LVEF improvement. Moreover, performance of stem cell infusion was the only determinant of ΔTs-SD improvement(p=0.008). Maximal exercise capacity at 6 month showed a good correlation with Ts-SD at 6 month after cell infusion(r=−0.05, p=0.001) but not with LVEF.
Conclusions: Stem cell therapy restored LV synchronous contraction in patients with MI. Improvement of LV dyssynchrony is accompanied by enhancement of LVEF and exercise capacity. Restoration of LV synchronicity could be plausible mechanisms for improvement of LV function and functional status of patients with MI who underwent stem cell therapy.