Background: Acute myocardial infarction remains a leading cause of chronic heart failure. Excessive myocardial oxygen demand relative to supply is the fundamental mechanism of myocardial infarction. We thus hypothesized that left ventricular (LV) mechanical unloading by the total support of transvascular LV assist device Impella could minimize oxygen demand, thereby reducing infarct size and preventing subsequent heart failure.

Methods and Results: In 20 dogs, we ligated the left anterior descending coronary artery for 180 minutes and then reperfused. We introduced Impella from 60 minutes after the onset of ischemia to 60 minutes after reperfusion. In the partial support group, Impella supported 50% of total cardiac output. In the total support group, systemic flow totally depends on Impella flow. Four weeks after ischemia/reperfusion (I/R), we compared LV function and infarct size among 4 groups: sham (no I/R), I/R (no Impella support), partial support, and total support. Compared with I/R, total support lowered LV end-diastolic pressure (15.0±3.5 versus 4.7±1.7 mm Hg; P<0.001), increased LV end-systolic elastance (4.3±0.8 versus 13.9±5.1 mm Hg/mL; P<0.001), and decreased NT-proBNP (N-terminal pro-B-type natriuretic peptide) level (4081±1123 versus 1773±390 pg/mL; P<0.05). Furthermore, total support markedly reduced infarct size relative to I/R, whereas partial support decreased infarct size to a lesser extent (I/R, 16.3±2.6; partial support, 8.5±4.3; and total support, 2.1±1.6%; P<0.001).

Conclusions: LV mechanical unloading by the total support of Impella during the acute phase of myocardial infarction reduced infarct size and prevented subsequent heart failure in dogs.

背景：急性心肌梗塞仍然是慢性心力衰竭的主要原因。相对于供应的过量心肌氧需求是心肌梗塞的根本机制。因此，我们假设通过经血管LV辅助设备Impella的全力支持可减轻左心室（LV）机械负荷，从而最大程度地减少氧气需求，从而减少梗塞面积并预防随后的心力衰竭。

方法和结果：在20只狗中，我们结扎了左前降支冠状动脉180分钟，然后再灌注。从缺血发作后60分钟到再灌注后60分钟，我们引入了Impella。在部分支持组中，Impella支持了总心输出量的50％。在总支持组中，系统流量完全取决于Impella流量。缺血/再灌注（I / R）后四周，我们比较了4组假手术（无I / R），I / R（无Impella支持），部分支持和总支持的4组患者的LV功能和梗死面积。与I / R相比，总支架降低了左室舒张末期压力（15.0±3.5对4.7±1.7 mm Hg; P <0.001），增加了左室舒张末期弹性（4.3±0.8对13.9±5.1 mm Hg / mL; P<0.001），并降低NT-proBNP（N末端pro-B型利钠尿肽）水平（4081±1123对1773±390 pg / mL; P <0.05）。此外，相对于I / R，总支持显着减少了梗塞面积，而部分支持在较小程度上降低了梗塞面积（I / R为16.3±2.6；部分支持为8.5±4.3；总支持为2.1±1.6％；P <0.001）。

结论：在心肌梗死急性期，Impella的总支持可减轻左心室机械负荷，从而减少了梗死面积并预防了随后的犬心力衰竭。