Abstract 13584: Beneficial Effects of Repeated Remote Ischemic Conditioning on Chronic Heart Failure at Chronic Phase After Myocardial Infarction
Background: Remote ischemic conditioning (RIC) by repeated treatment of transient limb ischemia is a clinically applicable method for protecting the heart against injury at the time of reperfusion.
Hypothesis: We hypothesized that the repeated treatment of RIC could improve cardiac dysfunction after myocardial infarction (MI).
Methods: MI was induced by permanent ligation of the left coronary artery. At 4 weeks after MI, rats were separated into the untreated (UT) group or the RIC-treated group (n=16-17). Control rats were subjected to a sham operation (n=11). The RIC treatment was performed by 5 cycles of 5 minutes of bilateral hindlimb ischemia and 5 minutes of reperfusion once a day. At 4 weeks after treatment, we assessed hemodynamics, oxidant stress by the level of derivatives of reactive-oxygen metabolites (d-ROM), cardiac function by echocardiography, tissue of myocardium genetically, and protein levels by Western blotting.
Results: Despite comparable blood pressure, body weight and MI size, ventricular weight / body weight in the RIC group was significantly decreased compared with UT (2.5±0.1 and 2.7±0.1 mg/g, respectively). Left ventricular (LV) end systolic volume was also significantly decreased and LV ejection fraction (LVEF) was significantly improved in the RIC group compared with the UT group (P<0.01). Moreover, LVEF in the RIC group tended to be improved compared with before treatment, while that in the UT group worsened more in 4 weeks.
Elevated serum level of d-ROM by MI was significantly reduced by the RIC treatment (605±24 and 495±23 U.CARR, respectively). Sirius red staining revealed that RIC treatment significantly attenuated MI-induced LV interstitial fibrosis in the boundary region (P<0.01). Heat shock protein 72 (Hsp72) level in boundary region of left ventricle was significantly increased in the UT group, compared with the non-MI control group. Interestingly, Hsp72 level in the same region of the RIC group was more increased compared with that in the UT group.
Conclusion: Repeated treatment of RIC inhibits adverse LV remodeling through the reduction of oxidant stress. These results may have clinical implications for the treatment of patients with evolving LV dysfunction.
- © 2013 by American Heart Association, Inc.