Effects of remote ischemic preconditioning on early myocardial post-infarction remodeling

Abstract

Introduction: It is known that remote ischemic preconditioning(rIPC) reduces infarct size in experimental models of myocardialinfarction (MI); while its effect is controversial in the clinical setting.Particularly, the effect of rIPC on post-infarction ventricular remod eling is unknown. The aim of this work is to evaluate the effect ofrIPC on early ventricular remodeling, considering the myocardialinfarction expansion.Methods: Male FVB mice, 2-6 months old, underwent MI by permanentligation (for 7 days) of the left anterior coronary artery; In a secondgroup, a rIPC protocol (3 cycles of 5 min ischemia/reperfusionin the left lower limb) was performed prior to MI. Finally, a third groupwas undergoing to left thoracotomy, but without myocardial ischemia(Sham). Infarct size was measured with triphenyltetrazolium, ventricularfunction by hemodynamic and echocardiography, and MMPs2 and 9 activity was evaluated by zymography.Results: There were no significant differences in the risk area andinfarct size between groups. IM decreased ejection fraction andarea shortening fraction to a value of 55,06±2,6% and 26,76±1,21%;respectively (p≤0,05 vs sham). rIPC improved systolic function increasingejection fraction and the area shortening fraction to a valueof 67,64%±1,42 and 37,41±2,37%, respectively (p≤0,05 vs IM).We did not observe significant differences between groups in theend-systolic stress values (afterload index). The relationship betweenend-systolic stress and ejection fraction was plotted, observinga significant improvement in the rIPC group, compared to the MIgroup. Finally, rIPC reduced significantly MMP-9 activity in the leftventricle (infarct area), but not MMP-2.Conclusion: We have showed that rIPC has a beneficial effect onearly remodeling, reducing myocardial post-infarction expansionand improving ventricular function. This beneficial effect could berelated to a lower MMP-9 activity.