Remote ischemic conditioning reduces myocardial infarct size and edema in patients with ST-segment elevation myocardial infarction

OBJECTIVES This study aimed to determine whether remote ischemic conditioning (RIC) initiated prior to primary percutaneous coronary intervention (PPCI) could reduce myocardial infarct (MI) size in patients presenting with ST-segment elevation myocardial infarction. BACKGROUND RIC, using transient limb ischemia and reperfusion, can protect the heart against acute ischemiareperfusion injury. Whether RIC can reduce MI size, assessed by cardiac magnetic resonance (CMR), is unknown. METHODS We randomly assigned 197 ST-segment elevation myocardial infarction patients with TIMI (Thrombolysis In Myocardial Infarction) flow grade 0 to receive RIC (four 5-min cycles of upper arm cuff inflation/deflation) or control (uninflated cuff placed on upper arm for 40 min) protocols prior to PPCI. The primary study endpoint was MI size, measured by CMR in 83 subjects on days 3 to 6 after admission. RESULTS RIC reduced MI size by 27%, when compared with the MI size of control subjects (18.0 10% [n ¼ 40] vs. 24.5 12.0% [n ¼ 43]; p ¼ 0.009). At 24 h, high-sensitivity troponin T was lower with RIC (2,296 263 ng/l [n ¼ 89] vs. 2,736 325 ng/l [n ¼ 84]; p ¼ 0.037). RIC also reduced the extent of myocardial edema measured by T2-mapping CMR (28.5 9.0% vs. 35.1 10.0%; p ¼ 0.003) and lowered mean T2 values (68.7 5.8 ms vs. 73.1 6.1 ms; p ¼ 0.001), precluding the use of CMR edema imaging to correctly estimate the area at risk. Using CMR-independent coronary angiography jeopardy scores to estimate the area at risk, RIC, when compared with the control protocol, was found to significantly improve the myocardial salvage index (0.42 0.29 vs. 0.28 0.29; p ¼ 0.03). CONCLUSIONS This randomized study demonstrated that in ST-segment elevation myocardial infarction patients treated by PPCI, RIC, initiated prior to PPCI, reduced MI size, increased myocardial salvage, and reduced myocardial edema.