Pathogenesis, Diagnosis and Risk Stratification in Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a genetically determined myocardial disease associated with sudden cardiac death (SCD). It is most frequently caused by mutations in genes encoding desmosomal proteins. However, there is growing evidence that ACM is not exclusively a desmosome disease but rather appears to be a disease of the connexoma. Fibroadipose replacement of the right ventricle (RV) had long been the hallmark of ACM, although biventricular involvement or predominant involvement of the left ventricle (LD-ACM) is increasingly found, raising the challenge of differential diagnosis with arrhythmogenic dilated cardiomyopathy (a-DCM). A-DCM, ACM, and LD-ACM are increasingly acknowledged as a single nosological entity, the hallmark of which is electrical instability. Our aim was to analyze the complex molecular mechanisms underlying arrhythmogenic cardiomyopathies, outlining the role of inflammation and autoimmunity in disease pathophysiology. Secondly, we present the clinical tools used in the clinical diagnosis of ACM. Focusing on the challenge of defining the risk of sudden death in this clinical setting, we present available risk stratification strategies. Lastly, we summarize the role of genetics and imaging in risk stratification, guiding through the appropriate patient selection for ICD implantation.

Diagnostic Value of the TpTe Interval in Children with Ventricular Arrhythmias

Background: The changes in the period of ventricular repolarization, i.e., QT interval, QTp (Q-Tpeak) and TpTe interval (Tpeak–Tend), make it possible to assess the electrical instability of the heart muscle, which may lead to the development of life-threatening ventricular arrhythmia. The aim of the study was to determine and evaluate the use of differences in T-wave morphology and durations of repolarization period parameters (QT, TpTe) in resting ECGs for children with ventricular arrhythmias. Methods: The retrospective analysis was made of the disease histories of 80 examined children with resting ECGs, which were admitted to the Children’s Cardiology Department. The study group consisted of 46 children aged 4 to 18 with ventricular arrhythmias and the control group consisted of 34 healthy children between 4 and 18 years of age, with no arrhythmias. Results: The duration of the TpTe interval was significantly (p < 0.001) longer in the group of children with ventricular arrhythmia with abnormal T-wave (bactrian/bifid, humid/biphasic) compared to the TpTe interval in children with ventricular arrhythmia with the normal repolarization period. The duration of the TpTe (p < 0.001), QTcB (p < 0.001) and QTcF (p < 0.001) intervals were significantly longer in the group of children with ventricular arrhythmias and with abnormal T-wave compared to the values of the TpTe, QTcB, and QTcF intervals of the control group with normal morphology of the repolarization period. Only the duration of the TpTe interval was significantly (p = 0.020) longer in the group of children with ventricular arrhythmia without clinical symptoms. Conclusions: Children with benign ventricular arrhythmias recorded on a standard ECG with prolonged TpTe and QT intervals and abnormal T-wave morphology require systematic and frequent cardiac check up with long term ECG recordings due to the possibility of future more severe ventricular arrhythmias. Further follow-up studies in even larger groups of patients are necessary to confirm the values of these repolarization parameters in clinical practice.

QT Interval Instability and Variability in Dogs with Hyperadrenocorticism

Hyperadrenocorticism is one of the most common endocrine diseases in dogs. In humans, it is clearly associated with a higher risk of cardiovascular events, but studies in dogs are scarce. To investigate the arrhythmogenic risk of dogs with hyperadrenocorticism, indices of variability and instability of the QT interval were studied in 38 dogs with hyperadrenocorticism and in 12 healthy dogs: variance (QTv), total instability (TI), short-term (STI) and long-term (LTI), and mean (QTm). Except for QTm, all parameters studied were higher in the hyperadrenocorticism group than in the control group. In addition, STI and QTv showed moderate positive correlation with left ventricle wall thickness. To a better understanding on the effect of the hypothalamus-pituitary-adrenal axis on ventricular repolarization, the hyperadrenocorticism group was subdivided according to the percentage of variation in plasma cortisol concentration (<30.1%; 30.1-60%; >60%) 8 hours after low-dose administration of dexamethasone. There was statistical difference in QTv, TI and LTI indices between the control group and the <30.1% and >60% groups, and in STI index between the control group and the >60% group. There was no statistical difference between sex groups in any of the electrocardiographic parameters studied. This result may indicate that the etiology of hyperadrenocorticism, and its consequent influence on hypothalamus-pituitary-adrenal axis could interfere on the heterogeneity of ventricular repolarization parameters in different ways, especially in the short-term stability; however further studies are necessary to understand the role of cortisol on electrical instability in dogs.

Late primary angioplasty (beyond 12 h): are we sure it should be avoided?

Optimal management for patients with ST-segment elevation myocardial infarction (STEMI) who arrive at a hospital late remains uncertain since evidence and real-world data are limited. Patients who present late with a STEMI are a heterogeneous population, and the clinical decision regarding percutaneous coronary intervention (PCI) should not be the same for all. One randomized clinical trial, multiple mechanistic studies, and contemporary registries suggest a presumed benefit for a prompt restoration of coronary flow even in late presenting STEMI. Crucial elements in decision-making are the presence of haemodynamic or electrical instability, and ongoing ischaemic signs or symptoms to tip the scales toward PCI. Among clinically stable, late-presenting patients, myocardial viability assessment and functional testing can identify yet another subgroup that may benefit from late PCI

Electrical Instability of Single-Walled Carbon Nanotube Network Thin-Film Transistors

The electrical instability of single-walled carbon nanotube (SWCNT) network-based thin-film transistors is investigated in atmospheric air and under vacuum. Atomic force microscopy images show that the nanotube bundles form X-type and Y-type nodes in the SWCNT-networkfilm. The Raman spectrum reveals that the structural defects in the SWCNTs are negligible. The fabricated SWCNT-network TFTs operate in a p-channel accumulation mode both in air and under vacuum. In contrast, TFTs exposed to atmospheric air environment exhibit lower drain currents and larger hysteresis compared with the vacuum environment case. An analysis of the time-dependent characteristic degradation of the SWCNT-network TFTs also demonstrates that the initial decay of the drain current in atmospheric air environment is more acute than that under vacuum. These results can be explained in terms of the hole-trapping behavior of the water molecules near the nanotubes or at the SWCNT/dielectric interface as well as the compensation effect of the electrons donated by water molecules with free holes in the SWCNT-networkfilm.

Electric myocardial inhomogeneity and stroke: connection and specifics

Funding Acknowledgements Type of funding sources: None. Background. The inconsistency of the literature data on the influence of different hemispheric localization of Cerebrovascular accident (CVA) on the development of cardiac arrhythmias suggests the expediency of further study of the so-called "zones" of the cerebral cortex associated with electrical instability of the myocardium. It is known that dispersion of QT interval and fragmented myocardial activity belong to the markers of electrical instability of the heart and are associated with arrhythmogenesis. The aim of the study. To study the severity of abnormalities of the parameters of electrical instability of myocardium in right and left hemispheric stroke localization in patients with hypertension. Material and methods. 111 patients with left hemispheric localization of ischemic stroke and 75 patients with right hemispheric stroke were examined. Hemorrhagic stroke was observed in 17 patients in the left hemisphere and in 13 patients in the right hemisphere. The average age was 58,2 ± 7,48 years. For all strokes, men prevailed (64% vs. 36%). For the first day of the stroke, all patients were evaluated for QT dispersion and fragmented myocardial activity on the device "Polyspectro-8EX" (Russia). Research results. Evaluation of the parameters of electrical instability of myocardium in patients with stroke revealed more pronounced disorders in hemorrhagic stroke of left hemispheric localization (Table 1). In ischemic stroke, the severity of electrophysiological parameters, reflecting the instability of the myocardium depending on the hemispheric localization, indicates the absence of differences. Conclusions. 1.The most pronounced disturbances in the parameters of electrical stability of the myocardium is observed in hemorrhagic stroke. 2.The severity of myocardial electrical instability in ischemic stroke is not associated with the localization of the focus.

Virus-Negative Necrotizing Coronary Vasculitis with Aneurysm Formation in Human SARS-CoV-2 Infection

We report a case of myopericarditis associated to SARS-CoV-2 infection with necrotizing coronary vasculitis of intramural vessels, giving rise to biventricular apical microaneurysms and to electrical instability. Negativity of myocardial polymerase chain reaction for the most common cardiotropic viruses and for SARS-CoV-2 suggested an immune-mediated myocardial and pericardial inflammatory disease. High dose (1 mg/Kg daily) prednisone and anti-viral (Remdesivir, IDA Business, Carrigtohill, County Cork, T45 DP77, Ireland) therapy led to resolution of cardiac inflammation and ventricular arrhythmias. Morpho-molecular characterization of endomyocardial tissue may improve the outcome in subjects with SARS-CoV-2-associated myopericarditis and coronary vasculitis.