Remote Ischemic Post-conditioning of the Lower Limb During Primary Percutaneous Coronary Intervention Safely Reduces Enzymatic Infarct Size in Anterior Myocardial Infarction: a Randomized Controlled Trial

Objectives This study sought to evaluate whether remote ischemic post-conditioning (RIPC) could reduce enzymatic infarct size in patients with anterior ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention (pPCI). Background Myocardial reperfusion injury may attenuate the benefit of pPCI. In animal models, RIPC mitigates myocardial reperfusion injury. Methods One hundred patients with anterior ST-segment elevation myocardial infarction and occluded left anterior descending artery were randomized to pPCI + RIPC (n = 50) or conventional pPCI (n = 50). RIPC consisted of 3 cycles of 5 min/5 min ischemia/reperfusion by cuff inflation/deflation of the lower limb. The primary endpoint was infarct size assessed by the area under the curve of creatinine kinase-myocardial band release (CK-MB). Secondary endpoints included the following: infarct size assessed by cardiac magnetic resonance delayed enhancement volume; T-2-weighted edema volume; ST-segment resolution >50%; TIMI (Thrombolysis In Myocardial Infarction) frame count; and myocardial blush grading. Results Four patients (2 RIPC, 2 controls) were excluded due to missing samples of CK-MB. A total of 96 patients were analyzed; median area under the curve CK-MB was 8,814 (interquartile range [IQR]: 5,567 to 11,325) arbitrary units in the RIPC group and 10,065 (IQR: 7,465 to 14,004) arbitrary units in control subjects (relative reduction: 20%, 95% confidence interval: 0.2% to 28.7%; p = 0.043). Seventy-seven patients underwent a cardiac magnetic resonance scan 3 to 5 days after randomization, and 66 patients repeated a second scan after 4 months. T-2-weighted edema volume was 37 +/- 16 cc in RIPC patients and 47 +/- 22 cc in control subjects (p = 0.049). ST-segment resolution >50% was 66% in RIPC and 37% in control subjects (p = 0.015). We observed no significant differences in TIMI frame count, myocardial blush grading, and delayed enhancement volume. Conclusions In patients with anterior ST-segment elevation myocardial infarction, RIPC at the time of pPCI reduced enzymatic infarct size and was also associated with an improvement of T-2-weighted edema volume and ST-segment resolution >50%.