Reflection of Cardioprotection by Remote Ischemic Perconditioning in Attenuated ST-Segment Elevation During Ongoing Coronary Occlusion in Pigs: Evidence for Cardioprotection from Ischemic Injury
Rationale: Reduction of infarct size (IS) by remote ischemic per-conditioning (perRIC) is evident only after several hours reperfusion.
Objective: To develop a potential real-time estimate of cardioprotection by perRIC we have analyzed the time course of ST-segment elevation.
Methods and Results: Anesthetized open-chest pigs were subjected to 60 min coronary occlusion and 180 min reperfusion (placebo; PLA; n=19). perRIC (n=18; 4x5 min/5 min hindlimb occlusion/reperfusion) was induced 20 min after coronary occlusion. Regional myocardial blood flow was measured with microspheres, areas of no-reflow with thioflavin-S, area at risk (AAR) with blue dye, and IS with TTC-staining. Phosphorylation of AKT1/2/3, ERK1/2, and STAT3 was determined by Western blot. ST-segment elevation was analyzed in a V2-like ECG-lead at baseline, 5 and 55 min coronary occlusion, and 10, 30, 60, and 120 min reperfusion. Transmural blood flow at 5 min coronary occlusion was not different between perRIC (0.029±0.015 ml/min/g; mean±SD) and PLA (0.024±0.018 ml/min/g) as was AAR (perRIC: 24±6% of the left ventricle; PLA: 21±4%). Areas of no-reflow tended to be smaller with perRIC (9±12% of AAR vs. 15±14% with PLA; p=0.13). IS with perRIC was 23±12% of AAR vs. 40±11% with PLA (p<0.001). perRIC increased phosphorylation of STAT3 at 120 min reperfusion by 196±142% vs. 109±120% with PLA (p= 0.047). The time courses of ST-segment elevation in perRIC and PLA protocols, respectively, were different (p=0.017). With similar ST-segment elevation at 5 min coronary occlusion (perRIC 282±34 µV; PLA 259±28 µV), partial recovery of ST-segment elevation between 5 and 55 min coronary occlusion was more pronounced with perRIC than PLA (by 111±84 vs. 15±94 µV; p=0.028).
Conclusions: IS reduction by perRIC is reflected in the ST-segment elevation during coronary occlusion in pigs, supporting the notion of protection from ischemic injury.
- ST-segment elevation
- remote ischemic perconditioning
- ischemia reperfusion injury
- infarct size
- Received January 23, 2018.
- Revision received February 16, 2018.
- Accepted February 20, 2018.