Prognostic value of minimal blood flow restoration in patients with acute myocardial infarction after reperfusion therapy

MicroRNA‑126 and VEGF enhance the function of endothelial progenitor cells in acute myocardial infarction

Previous studies have found that microRNA-126 (miR-126) overexpression can exert beneficial effects on endothelial function and angiogenesis. The role of miR-126 was previously reported to be by directly limiting the activities of negative regulators of the vascular endothelial growth factor (VEGF) pathway, such as PI3K regulation subunit 2 (PIK3R2). The aim of the present study was to investigate the role of the miR-126/PIK3R2/VEGF axis in endothelial progenitor cells (EPCs) under hypoxic conditions. An in vitro hypoxia model in EPCs was established by exposing EPCs to hypoxia (O²/N²/CO², 1/94/5) for 72 h, before reverse transcription-quantitative PCR (RT-qPCR) and western blot analyzes were used to measure miR-126 and PIK3R2 expression in EPCs. The proliferation, migration and tube-forming ability of the transfected cells were measured using MTT, Transwell and tube formation assays, respectively. miR-126 expression was found to be lower in EPCs in the hypoxia group compared with that in the control group (P<0.01). The expression of PIK3R2, a direct target gene of miR-126, was found to be higher in the hypoxia group compared with that in the control group (P<0.01). miR-126 mimic and VEGF-plasmid co-transfection improved the proliferation, migration, tube-forming ability and restored the phosphorylation of AKT in EPCs under hypoxic conditions (all P<0.01). In addition, the effects of miR-126 mimic on hypoxia-induced EPCs were reversed by PIK3R2-plasmid co-transfection, whilst the effects of VEGF-plasmid were enhanced further by co-transfection with the miR-126 mimic. In conclusion, miR-126 promoted the functions of EPCs under hypoxic conditions by negatively targeting PIK3R2, whilst the combined overexpression of miR-126 and VEGF enhanced these aforementioned effects.

Heterogeneity of the no-reflow group after primary percutaneous coronary intervention due to ST-segment elevation myocardial infarction - are there sex differences?

AIMS

Assessment of the diversity in the no-reflow population after primary percutaneous coronary intervention (pPCI) due to ST-segment elevation myocardial infarction (STEMI). Are there any gender-related differences?

MATERIAL AND METHODS

Analysis of 1063 STEMI patients with Thrombolysis in Myocardial Infarction (TIMI) grade 0 or 1 following pPCI. The study group consisted of 685 patients with TIMI grade 0 and of 378 patients with TIMI grade 1. We analyzed clinical characteristics, in-hospital mortality and 2-year follow-up in both groups.

RESULTS

Among women with the TIMI grade 1 an atrial fibrillation, tachycardia and impaired ejection fraction were more common than in men. The vessel responsible for myocardial infarction was most commonly the left anterior descending (LAD) in women, whereas the right coronary artery (RCA) in men. These differences were not observed in group with TIMI grade 0. We observed a higher incidence of in-hospital death in the population with TIMI grade 0 compared with TIMI grade 1 (21.9% vs 17.2%; p 0.0189). In the TIMI grade 1 group there was significantly higher incidence of in-hospital mortality in women compared to men (13.2% vs 22.7%; p 0,0159). Among women with postprocedural TIMI grade 0 in all periods of long-term follow-up the mortality was significantly higher compared to men (9.5% vs 17%; p 0,0111; 11.8% vs 19.7%; p 0.0139 and 16.7% vs 23.9%; p 0.043 for 6-,12-months and 2-years of follow up respectively).

CONCLUSIONS

Patients with no-reflow phenomenon in infarct related artery after pPCI constitute a more diverse group than previously thought. Some differences are most likely gender-specific. The female sex might have an adverse effect on in-hospital mortality in case of TIMI grade 1 and on the long-term prognosis among patients with TIMI grade 0.

Microvascular Obstruction Evaluation Using Cardiovascular Magnetic Resonance (CMR) in ST-Elevated Myocardial Infarction (STEMI) Patients

BACKROUND

Restoration of blood flow in epicardial coronary artery in patients with acute myocardial infarction can, but does not have to restore efficient blood flow in coronary circulation. The aim of the study was a direct comparison of microvascular obstruction (MVO) detected by rest and stress perfusion imaging and gadolinium enhancement obtained 2 min. (early MVO) and 15 min. (delayed MVO) post contrast.

MATERIAL/METHODS

106 patients with first anterior myocardial infarction were studied. Cardiovascular magnetic resonance (CMR) was performed 5±2 days after primary percutaneous coronary intervention (pPCI). Stress and rest perfusion imaging was performed as well as early and delayed gadolinium enhancement and systolic function assessment. Scoring of segmental function, perfusion defect, MVO and scar transmurality was performed in 16 segment left ventricular model.

RESULTS

The prevalence of MVO varies significantly between imaging techniques ranging from 48.8% for delayed MVO to 94% with stress perfusion. Median sum of scores was significantly different for each technique: stress perfusion 13 (7; 18), rest perfusion 3 (0.5; 6), early MVO 3 (0; 8), delayed MVO 0 (0; 4); p<0.05. Infarct size, stress and rest perfusion defects were independent predictors of LV EF at discharge from hospital.

CONCLUSIONS

Imaging protocol has a significant impact on MVO results. The study is the first to describe a stress-induced MVO in STEMI patients. Further research is needed to evaluate its impact on a long term prognosis.

Clinical importance of hyperemic coronary blood flow (thrombolysis in myocardial infarction-intravenous flow) after primary percutaneous coronary intervention

We aimed to investigate clinical, demographic and angiographic factors associated with hyperemic coronary blood flow (HCBF) and the relation of HCBF with mortality at 30 days. Our study included 809 consecutive patients with acute ST-segment elevation myocardial infarction who underwent primary percutaneous coronary intervention (PCI). We divided corrected thrombolysis in myocardial infarction (TIMI) frame count (TFC) values into three tertiles: less than 14, 14-28 and more than 28. Corrected TFC less than 14 was defined as HCBF or TIMI intravenous flow. The primary end-point of the present study was all-cause mortality within 30 days. Among the HCBF group (n = 58), the patients with poor myocardial perfusion demonstrated the highest mortality rate within the 30-day follow-up period (33%). Low TIMI myocardial perfusion grade, history of no smoking, left ventricular ejection fraction (LVEF), and high Killip status and low LVEF were found to be independently associated with 1-month all-cause mortality. The present study showed that HCBF after primary PCI has a high 30-day mortality when associated with impaired reperfusion.

Complement factor concentrations in patients with acute myocardial infarction: time course and ability to predict left ventricular dysfunction

Aim: Inflammatory processes may contribute to myocardial ischemia/reperfusion injury after myocardial infarction (MI). We aimed to evaluate the predictive value of complement factor concentrations for the occurrence of post-MI left ventricular (LV) dysfunction. Patients & methods: Fifty-five patients with acute MI were included. Complement factors and CRP were assessed at hospital admission (HA) and during the first 3 days. LV ejection fraction was determined by echocardiography before hospital discharge. Results: Total hemolytic complement (CH50) on admission and peak CRP during the first hospitalization days were higher in patients who developed LV dysfunction (LV ejection fraction ≤45%). By contrast, neither absolute concentrations of single complement factor concentrations nor changes in these concentrations over time were associated with the occurrence of LV dysfunction. CH50 at HA was independently associated with LV dysfunction. Conclusion: This study generates the hypothesis that CH50 concentration at HA in patients with acute MI may identify individuals at high risk for LV dysfunction.