Reperfusion strategies in ST-elevation myocardial infarction--current status and perspectives for early and pre-hospital treatment

Differential Effects of Reperfusion on Cardiac Mitochondrial Subpopulations in a Preclinical Porcine Model of Acute Myocardial Infarction

Acute myocardial infarction (AMI) leads to localized cardiac ischemia and can be fatal if untreated. Despite being treatable, the threat of ischemia-reperfusion (IR) injury remains high. Mitochondria are central to both propagation and mitigation of IR injury, and cardiac mitochondria are categorized into two major subtypes-subsarcolemmal and interfibrillar mitochondria (SSM and IFM, respectively). We hypothesized that, in our pre-clinical porcine model of AMI, SSM and IFM are differentially affected by reperfusion. AMI was induced in female pigs by balloon occlusion of the left anterior descending artery for 45 min, followed by 4 h of reperfusion. At the end of reperfusion, animals were euthanized. Cardiac SSM and IFM from the affected ischemic area and a nearby non-ischemic area were isolated to compare mitochondrial function using substrates targeting mitochondrial electron transport chain complexes I and II. Despite detecting overall significant differences in mitochondrial function including yield, mitochondrial S3 and S4 respirations, and calcium retention, consistent individual functional differences in the two mitochondrial subpopulations were not observed, both between the two mitochondrial subtypes, as well as between the ischemic and non-ischemic tissue. Nonetheless, this study describes the mitochondrial subtype response within the initial few hours of reperfusion in a clinically relevant model of AMI, which provides valuable information needed to develop novel mitochondrially targeted therapies for AMI.

Stenting versus non-stenting treatment of intermediate stenosis culprit lesion in acute ST-segment elevation myocardial infarction: a multicenter randomized clinical trial

Background

The benefit/risk ratio of stenting in acute ST-segment elevation myocardial infarction (STEMI) patients with single vessel intermediate stenosis culprit lesions merits further study, therefore the subject of the present study.

Methods and results

It was a prospective, multicenter, randomized controlled trial. Between April 2012 and July 2015, 399 acute STEMI patients with single vessel disease and intermediate (40%–70%) stenosis of the culprit lesion before or after aspiration thrombectomy and/or intracoronary tirofiban (15 µg/kg) were enrolled and were randomly assigned (1: 1) to stenting group (n = 201) and non-stenting group (n = 198). In stenting group, patients received pharmacologic therapy plus standard percutaneous coronary intervention (PCI) with stent implantation. In non-stenting group, patients received pharmacologic therapy and PCI (thrombectomy), but without dilatation or stenting. Primary endpoint was 12-month rate of major adverse cardiac and cerebrovascular events (MACCE), a composite of cardiac death, non-fatal myocardial infarction (MI), repeat revascularization and stroke. Secondary endpoints were 12-month rates of all cause death, ischemia driven admission and bleeding complication. Median follow-up time was 12.4 ± 3.1 months. At 12 months, MACCE occurred in 8.0% of the patients in stenting group, as compared with 15.2% in the non-stenting group (adjusted HR: 0.42, 95% CI: 0.19–0.89, P = 0.02). The stenting group had lower non-fatal MI rate than non-stenting group, (1.5% vs. 5.5%, P = 0.03). The two groups shared similar cardiac death, repeat revascularization, stroke, all cause death, ischemia driven readmission and bleeding rates at 12 months.

Conclusions

Stent implantation had better efficacy and safety in reducing MACCE risks among acute STEMI patients with single vessel intermediate stenosis culprit lesions.