Left ventricular unloading with intra‐aortic counter pulsation prior to reperfusion reduces myocardial release of endothelin‐1 and decreases infarction size in a porcine ischemia‐reperfusion model

Objectives: We tested the hypothesis that unloading the left ventricle with intra‐aortic balloon counter‐pulsation just prior to reperfusion provides infarct salvage compared with left ventricular (LV) unloading postreperfusion or reperfusion alone. Background: Previous reports demonstrated infarct salvage with complete LV unloading with an LVAD prior to reperfusion; however, partial LV unloading using intra‐aortic balloon pumps (IABPs) has not been evaluated. Methods: Twenty‐eight Yorkshire pigs were subjected to 1 hr of left anterior descending artery occlusion and 4 hr of reperfusion. An IABP was inserted and activated just prior to reperfusion (IABP‐Pre), or 15 min after reperfusion (IABP‐Post), or not at all (control). Results: At baseline, the hemodynamic data were similar in the three groups. Myocardial infarct size expressed a percentage of zone at risk in control animals was 44.9% ± 4.8%, IAPB‐Pre group 20.9% ± 5.1% ( P < 0.05 compared to control), and IABP‐Post group 33.2 ± 6.1% ( P = 0.16 vs. control group). There was a correlation between transcardiac endothelin‐1 release at 15 min postreperfusion and infarct size ( r = 0.59). Conclusion: LV unloading with an IABP prior to reperfusion reduces the extent of myocardial necrosis in hearts subjected to 1 hr of left anterior descending artery occlusion and 4 hr of reperfusion compared with either reperfusion alone or LV unloading after reperfusion. Inhibition of myocardial ET‐1 release by LV unloading may be a significant mechanism of myocardial protection. These data suggest that in high‐risk STEMI patients, IABP unloading prior to reperfusion might be more beneficial than IABP placement postreperfusion. © 2008 Wiley‐Liss, Inc.