Reperfusion ventricular arrhythmia bursts identify larger infarct size in spite of optimal epicardial and microvascular reperfusion using cardiac magnetic resonance imaging

Role of miRNA-1 and miRNA-21 in Acute Myocardial Ischemia-Reperfusion Injury and Their Potential as Therapeutic Strategy

Coronary artery disease remains the leading cause of death. Acute myocardial infarction (MI) is characterized by decreased blood flow to the coronary arteries, resulting in cardiomyocytes death. The most effective strategy for treating an MI is early and rapid myocardial reperfusion, but restoring blood flow to the ischemic myocardium can induce further damage, known as ischemia-reperfusion (IR) injury. Novel therapeutic strategies are critical to limit myocardial IR injury and improve patient outcomes following reperfusion intervention. miRNAs are small non-coding RNA molecules that have been implicated in attenuating IR injury pathology in pre-clinical rodent models. In this review, we discuss the role of miR-1 and miR-21 in regulating myocardial apoptosis in ischemia-reperfusion injury in the whole heart as well as in different cardiac cell types with special emphasis on cardiomyocytes, fibroblasts, and immune cells. We also examine therapeutic potential of miR-1 and miR-21 in preclinical studies. More research is necessary to understand the cell-specific molecular principles of miRNAs in cardioprotection and application to acute myocardial IR injury.

A Bibliometric Analysis of 14,822 Researches on Myocardial Reperfusion Injury by Machine Learning

Myocardial ischemia is the major cause of death worldwide, and reperfusion is the standard intervention for myocardial ischemia. However, reperfusion may cause additional damage, known as myocardial reperfusion injury, for which there is still no effective therapy. This study aims to analyze the landscape of researches concerning myocardial reperfusion injury over the past three decades by machine learning. PubMed was searched for publications from 1990 to 2020 indexed under the Medical Subject Headings (MeSH) term “myocardial reperfusion injury” on 13 April 2021. MeSH analysis and Latent Dirichlet allocation (LDA) analyses were applied to reveal research hotspots. In total, 14,822 publications were collected and analyzed in this study. MeSH analyses revealed that time factors and apoptosis were the leading terms of the pathogenesis and treatment of myocardial reperfusion injury, respectively. In LDA analyses, research topics were classified into three clusters. Complex correlations were observed between topics of different clusters, and the prognosis is the most concerned field of the researchers. In conclusion, the number of publications on myocardial reperfusion injury increases during the past three decades, which mainly focused on prognosis, mechanism, and treatment. Prognosis is the most concerned field, whereas studies on mechanism and treatment are relatively lacking.

Editor's Choice- Reperfusion cardiac arrhythmias and their relation to reperfusion-induced cell death

Reperfusion does not only salvage ischaemic myocardium but can also cause additional cell death which is called lethal reperfusion injury. The time of reperfusion is often accompanied by ventricular arrhythmias, i.e. reperfusion arrhythmias. While both conditions are seen as separate processes, recent research has shown that reperfusion arrhythmias are related to larger infarct size. The pathophysiology of fatal reperfusion injury revolves around intracellular calcium overload and reactive oxidative species inducing apoptosis by opening of the mitochondrial protein transition pore. The pathophysiological basis for reperfusion arrhythmias is the same intracellular calcium overload as that causing fatal reperfusion injury. Therefore both conditions should not be seen as separate entities but as one and the same process resulting in two different visible effects. Reperfusion arrhythmias could therefore be seen as a potential marker for fatal reperfusion injury.

Prognostic Significance of Complex Ventricular Arrhythmias Complicating ST-Segment Elevation Myocardial Infarction

The aim of the study was to assess the clinical significance of complex ventricular arrhythmias (VAs) (sustained ventricular tachycardia [sVT] and ventricular fibrillation [VF]) in patients with ST-segment elevation myocardial infarction (STEMI) depending on timing of arrhythmia. We analyzed 4,363 consecutive patients with STEMI treated invasively between 2004 and 2014. The median follow-up was 69.6 months (range: 0 to 139.8 months). The study population was divided into 2 main groups; VA group encompassed 476 patients (10.91%) with VAs, whereas 3,887 subjects (89.09%) without VT or VF were included into the control group. In VA population, prereperfusion VA (34.24%; n = 163) was the most common arrhythmia, whereas reperfusion-induced, early postreperfusion, and late postreperfusion VAs were diagnosed in 103 (21.64%), 103 (21.64%), and 107 (22.48%) patients, respectively. Every type of sVT or VF complicating STEMI portended significantly worse in-hospital prognosis, however a late onset arrhythmia was associated with the highest (over fivefold) and reperfusion-induced VA with the lowest (less than threefold) increase in mortality risk compared with the control group. On the contrary, long-term mortality was significantly increased only in subjects with late postreperfusion and prereperfusion VAs compared with VA-free population (43.93% and 36.81%, respectively vs 22.58%; p <0.001). Apart from cardiogenic shock on admission, late postreperfusion (hazard ratio 3.39) and prereperfusion VAs (hazard ratio 2.76) were the strongest independent predictors of death in the analyzed population. In conclusion, 1 in 10 patients with STEMI treated invasively was affected by sVT or VF. The clinical impact of VAs was strongly dependent on timing of arrhythmia.