Figure 2 Ejection fraction and scar surface area. Transthoracic echocardiography (left axis, solid bars) at the study endpoint (6 weeks post-myocardial infarction, 3 weeks post-graft therapy) revealed a normal left ventricular ejection fraction (EF) for sham (n=7), a significantly decreased EF (33%±2% vs 76±3%, p<0.0001) for the HFrEF group (n=27), and a comparable EF (39%±5% vs 33±2%, p=0.2549) for the graft-treated HFrEF group (n=13). Furthermore, epicardial monophasic action potential amplitude was used to create a two-dimensional color map of the epicardium (maps shown in figure 3), which revealed a large region of scar tissue in the vascular territory of the left coronary artery in HFrEF rats (n=29; right axis, dashed bars). This scar area was not observed in sham rats (n=7; 33.0%±2.4% vs 0.3±1.5%, p<0.0001), and graft-treated rats (n=12) exhibited a slightly smaller percentage of scar area (25.2%±6.6% vs 33.0±2.4%, p=0.4310). * denotes statistical significance vs sham.