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Background: Torsade de pointes is a potentially lethal polymorphic ventricular tachyarrhythmia that can occur in the setting of long QT syndrome (LQTS). LQTS is multi-hit in nature and multiple factors combine their effects leading to increased arrhythmic risk. While hypokalemia and multiple medications are accounted for in LQTS, the arrhythmogenic role of systemic inflammation is increasingly recognized but often overlooked. We tested the hypothesis that the inflammatory cytokine interleukin(IL)-6 will significantly increase the incidence of arrhythmia when combined with other pro-arrhythmic conditions (hypokalemia and the psychotropic medication, quetiapine)., Methods: Guinea pigs were injected intraperitoneally with IL-6/soluble IL-6 receptor and QT changes were measured in vivo. Subsequently, hearts were cannulated via Langendorff perfusion for ex vivo optical mapping measurements of action potential duration (APD 90 ) and arrhythmia inducibility. Computer simulations (MATLAB) were performed to investigate I Kr inhibition at varying IL-6 and quetiapine concentrations., Results: IL-6 prolonged QTc in vivo guinea pigs from 306.74 ± 7.19 ms to 332.60 ± 8.75 ms (n = 8, p = .0021). Optical mapping on isolated hearts demonstrated APD prolongation in IL-6- vs saline groups (3Hz APD 90 :179.67 ± 2.47 ms vs 153.5 ± 7.86 ms, p = .0357). When hypokalemia was introduced, the APD 90 increased to 195.8 ± 5.02 ms[IL-6] and 174.57 ± 10.7 ms[saline] (p = .2797), and when quetiapine was added to hypokalemia to 207.67 ± 3.03 ms[IL-6] and 191.37 ± 9.49 ms[saline] (p = .2449). After the addition of hypokalemia ± quetiapine, arrhythmia was induced in 75% of IL-6-treated hearts (n = 8), while in none of the control hearts (n = 6). Computer simulations demonstrated spontaneous depolarizations at ∼83% aggregate I Kr inhibition., Conclusions: Our experimental observations strongly suggest that controlling inflammation, specifically IL-6, could be a viable and important route for reducing QT prolongation and arrhythmia incidence in the clinical setting., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Nabil El-Sherif reports financial support was provided by Narrows Institute for Biomedical Research and Education, Inc. Mohamed Boutjdir reports financial support was provided by Biomedical Laboratory Research & Development Service of Veterans Affairs Office of Research and Development. Mohamed Boutjdir reports financial support was provided by National Heart Lung and Blood Institute. Mohamed Boutjdir reports financial support was provided by US Department of Defense., (Published by Elsevier Inc.)

Background: Cardiac implantable electronic device (CIED) implantation rates as well as the clinical and procedural characteristics and outcomes in patients with known active coronavirus disease 2019 (COVID-19) are unknown., Objective: The purpose of this study was to gather information regarding CIED procedures during active COVID-19, performed with personal protective equipment, based on an international survey., Methods: Fifty-three centers from 13 countries across 4 continents provided information on 166 patients with known active COVID-19 who underwent a CIED procedure., Results: The CIED procedure rate in 133,655 hospitalized COVID-19 patients ranged from 0 to 16.2 per 1000 patients (P <.001). Most devices were implanted due to high-degree/complete atrioventricular block (112 [67.5%]) or sick sinus syndrome (31 [18.7%]). Of the 166 patients in the study survey, the 30-day complication rate was 13.9% and the 180-day mortality rate was 9.6%. One patient had a fatal outcome as a direct result of the procedure. Differences in patient and procedural characteristics and outcomes were found between Europe and North America. An older population (76.6 vs 66 years; P <.001) with a nonsignificant higher complication rate (16.5% vs 7.7%; P = .2) was observed in Europe vs North America, whereas higher rates of critically ill patients (33.3% vs 3.3%; P <.001) and mortality (26.9% vs 5%; P = .002) were observed in North America vs Europe., Conclusion: CIED procedure rates during known active COVID-19 disease varied greatly, from 0 to 16.2 per 1000 hospitalized COVID-19 patients worldwide. Patients with active COVID-19 infection who underwent CIED implantation had high complication and mortality rates. Operators should take these risks into consideration before proceeding with CIED implantation in active COVID-19 patients., (Copyright © 2021 Heart Rhythm Society. All rights reserved.)

Cardiac K + channelopathies account for a significant proportion of arrhythmias and sudden cardiac death (SCD) in subjects without structural heart disease. It is well recognized that genetic defects are key factors in many cases, and in practice, the term cardiac channelopathies currently coincides with inherited cardiac channelopathies. However, mounting evidence demonstrate that not only genetic alterations but also autoimmune and inflammatory factors can cause cardiac K + -channel dysfunction and arrhythmias in the setting of a structurally normal heart. In particular, it has been demonstrated that specific autoantibodies as well as inflammatory cytokines can modulate expression and/or function of different K + channels in the heart, resulting in a disruption of the cardiac action potential and arrhythmias/sudden cardiac death. Awareness about the existence of these newly recognized forms is essential to identify and adequately manage affected patients. In the present review, we focus on autoimmune and inflammatory K + channelopathies as a novel mechanism for cardiac arrhythmias and analyze the recent advancements in this topic, providing complementary basic, clinical, and population health perspectives., (Copyright © 2019 Heart Rhythm Society. All rights reserved.)

Background: Hemorrhagic transformation (HT) is a multifactorial phenomenon and represents a possible complication of ischemic stroke, especially after thrombolytic treatment. Increased arterial stiffness has been associated with intracranial hemorrhage, but there is no evidence of association with HT after thrombolytic therapy. The aim of our study is to investigate a possible link between arterial stiffness and HT occurrence after thrombolytic therapy in patients with ischemic stroke., Methods: We enrolled 258 patients (135 males, 123 females; mean age: 73±12years) with acute ischemic stroke undergoing intravenous thrombolysis or/and mechanical thrombectomy. All stroke patients underwent neuroimaging examination, 24-h heart rate and blood pressure monitoring and brain CT-scan after 24-72h to evaluate HT occurrence. The linear regression slope of diastolic on systolic blood pressure was obtained and assumed as a global measure of arterial compliance, and its complement (1 minus the slope), named arterial stiffness index (ASI), has been taken as a measure of arterial stiffness., Results: Out of 258, HT occurred in 55 patients. ASI was significantly higher in patients with HT than in patients without HT (0.70±0.12 vs 0.62±0.14, p<0.001). Logistic regression model showed ASI as independent predictors of HT (OR: 1.9, 95% CI: 1.09-3.02, for every 0.2 increase of ASI): in particular, OR was 5.2 (CI: 2.22-12.24) when ASI was >0.71, in comparison with ASI lower than 0.57., Conclusions: Our results point to arterial stiffness as a novel independent risk factor for HT after ischemic stroke treated with thrombolysis, suggesting a particularly high bleeding risk when ASI is >0.71., (Copyright © 2017 Elsevier B.V. All rights reserved.)

When compared to the general population, patients with rheumatoid arthritis (RA) have an overall standard mortality ratio of approximately two, with more than 50% of premature deaths attributable to cardiovascular disease (CVD). Moreover, RA patients were twice as likely to experience sudden cardiac death (SCD) compared with non-RA subjects, as a putative consequence of an increased incidence of malignant arrhythmias. Accordingly, mounting data indicate that in patients affected with RA the risk of developing rhythm disturbances, particularly tachyarrhythmias, is high. Although a number of papers reviewing the problem of cardiovascular involvement in RA are currently available, the main focus is on the mechanisms of accelerated atherosclerosis and related ischemic consequences in the clinical setting. On the contrary, only little consideration has been specifically given to the arrhythmic risk so far. In the light of this concern, in the present paper we reviewed the topic with the aim to put together the apparently fragmentary existing information, with particular attention to the putative role of chronic systemic inflammation characterizing the disease. In fact, although the underlying mechanisms accounting the arrhythmogenic substrate in RA are probably intricate, the leading role seems to be played by inflammatory activation, able to promote arrhythmias either indirectly, by accelerating the development of structural CVD, and directly by affecting cardiac electrophysiology. In this view, lowering inflammatory burden through an increasingly tight control of disease activity may represent the most effective intervention to reduce arrhythmic risk and prevent life-threatening complications in these patients., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Raynaud's phenomenon, categorized as primary and secondary when occurring isolated or in association with an underlying disease, respectively, is a paroxysmal and recurrent acral ischemia resulting from an abnormal arterial vasospastic response to cold or emotional stress. The key issue in the pathogenesis of Raynaud's phenomenon is presumed to be a dysregulation in the mechanisms of vascular motility resulting in an imbalance between vasodilatation and vasoconstriction. Homocysteine, a non-protein forming sulphured amino acid proposed as an independent risk factor for atherothrombosis in the general population, clearly demonstrated to produce vascular damage through mechanisms also including endothelial injury and modifications in circulating mediators of vasomotion. The rationale for homocysteine involvement in the pathogenesis of Raynaud's phenomenon led some authors to investigate the possible association between mild hyperhomocysteinemia and such a vascular disturbance, particularly in the course of connective tissue disease. Here we review data regarding this putative association and the supposed mechanisms involved, also discussing the emblematic case of a patient with new-onset severe Raynaud's phenomenon and markedly elevated homocysteinemia., (Copyright 2009 Elsevier B.V. All rights reserved.)

The arrhythmogenicity of anti-Ro/SSA antibodies for the foetal heart and their crucial role in the development of congenital heart block is now well established, representing a paradigmatic model of passively acquired autoimmunity. Recently, intriguing data suggest that also the adult heart may represent a possible target of anti-Ro/SSA antibody-mediated autoimmune injury. The prolongation of the QTc interval, possibly resulting from a direct inhibitory interaction between the anti-Ro/SSA antibodies and the potassium current I(Kr) in the heart seems the abnormality more frequently observed in adults with anti-Ro/SSA-positive CTD. Although the possibility that anti-Ro/SSA positivity may be considered a risk factor for arrhythmic sudden death in adults has not been demonstrated as yet, preliminary data suggest a relationship among anti-Ro/SSA antibodies, QTc prolongation, and the prevalence of ventricular arrhythmias, also life threatening, in adult patients.

Hyperhomocysteinemia is independently associated with the development of coronary, cerebral and peripheral vascular disease and deep-vein thrombosis in the general population. The evidence that cardiovascular involvement is particularly frequent and advanced in patients affected with several autoimmune diseases (AD), in which hyperhomocysteinemia represent a common finding, led to an intensive investigation on homocysteine (Hcy) as a putative risk factor for the development of cardiovascular disease in such subjects. Indeed, recent data intriguingly expanded the spectrum of the possible pathogenetic implications for hyperhomocysteinemia in the course of AD. In fact, a bi-directional link seems to connect Hcy and the immuno-inflammatory activation characterizing AD, in which immuno-inflammatory activation may contribute to Hcy increase, and Hcy, in its turn, may act as a pro-inflammatory and immuno-stimulating molecule putatively cooperating to the injury of the disease-specific target organs, at least in rheumatoid arthritis and inflammatory bowel disease. Moreover, Hcy may be also a trigger of autoimmune reactions through its capability to bind and structurally modify specific proteins, then resulting in neoantigens formation potentially relevant either in the onset of specific AD and in the progression of the associated cardiovascular damage. More investigation is necessary to fully define the clinical relevance of such phenomena.

Cardiovascular involvement is common in connective tissue diseases (CTD), with relevant implications in terms of morbidity and mortality. Rhythm disturbances, i.e. conduction defects and tachyarrhythmias, represent a frequent clinical manifestation of CTD-associated cardiovascular damage and a possible cause of sudden death. The underlying arrhythmogenic mechanisms are probably multiple and intriguing, even though the myocardial fibrosis frequently observed at the pathological examination seems to play a pivotal role. Myocardial fibrosis is produced directly by inflammatory processes, or indirectly as a consequence of coronary artery occlusive disease, and it may affect the conduction system also representing the pathological substrate for reentry circles. An overview of CTD-associated cardiac rhythm disturbances is here provided. Among CTD-associated rhythm disorders, congenital heart block (CHB), which represents the main feature of neonatal lupus, a rare syndrome related to the transplacental passage of autoantibodies from anti-Ro/SSA-positive mother to their newborns, seems to acknowledge a peculiar mechanism of disease possibly dependent on a direct arrhythmogenicity of anti-Ro/SSA antibodies. Moreover, new anti-Ro/SSA-associated EKG abnormalities have been recently described in children (sinus bradycardia and corrected QT (QTc) interval prolongation) as well as in adults (QTc interval prolongation).

We assayed the redox forms of cysteine (reduced [CSH], oxidized [CSSC], and bound to protein [CS-SP]), cysteinylglycine (CGSH; cysteinylgycine disulfide [CGSSGC] and cysteinylglycine-protein mixed disulfide [CGS-SP]), glutathione (GSH; glutathione disulfide [GSSG] and glutathione-protein mixed disulfide [GS-SP]), homocysteine (Hcy; homocystine [HcyS] and homocystine-protein mixed disulfides [bHcy]), and protein sulfhydryls in the plasma of healthy subjects (divided into 8 groups ranging in age from birth to 70 years) and patients with mild hyperhomocysteinemia associated with cardiovascular disease (heart-transplant patients) or vascular atherosclerosis, with or without renal failure. In healthy individuals, levels of disulfides and protein-mixed disulfides were more abundant than those of thiols, and those of protein-thiol mixed disulfides were higher than disulfides. Concentrations of CSH, GSH, and CGSH in the various groups had profiles characterized by a maximum over time. The concentration of Hcy was unchanged up to the age of 30 years, after which it increased. CSSC concentration increased gradually with age, whereas concentrations of the other disulfides were essentially unchanged. By contrast, the concentrations of all protein-thiol mixed disulfides, especially those with CSH, increased gradually with age. Ranks of distribution of the reduced forms changed with age (at birth, CSH > CGSH > GSH > Hcy; in 1- to 2-year-olds, CSH > GSH > CGSH > Hcy; and in 51- to 70-year-olds, CSH > CGSH = GSH > Hcy), whereas those of disulfides and protein-thiol mixed disulfides were substantially unchanged (in all age groups, CSSC > CGSSGC > GSSG = HcyS and CS-SP > CGS-SP > bHcy > GS-SP). In patients with pathologic conditions, plasma levels of disulfide forms CSSC, HcyS, CS-SP, and bHcy were significantly increased, whereas other redox forms of thiols were unchanged or showed variations opposite (increasing or decreasing) to control values. Maximal increases in disulfides and protein-thiol mixed disulfides were associated with renal failure. Our data suggest that increases in plasma bHcy concentrations in subjects with pathologic conditions were more likely the result of activation of thiol-disulfide exchange reactions between free reduced Hcy and CS-SP than of a direct action of reactive oxygen species.

Hyperhomocysteinemia has recently been suggested to contribute to the progression of the so-called chronic rejection or cardiac allograft vasculopathy (CAV) in heart-transplant patients in which the major determinant of the increase in homocysteine (Hcy) was the progressive decline of renal function. The exact mechanisms of tissue injury by Hcy is unknown, but some aspects of its toxicity have been related to its capacity for altering the redox state of plasma and forming protein adducts by intermediate lactone. To study the relationships between Hcy levels and variations in the redox state governed by thiols, plasma levels of Hcy, cysteine, glutathione, cysteinylglycine, and corresponding disulfides and protein-mixed disulfides were evaluated in subjects with moderate hyperhomocysteinemia represented by heart-transplant patients with (HTRF) and without (HT) renal failure, as well as patients with renal failure of different origin (RF), and compared with those of a control group (C) of normal subjects matched for age and sex. Plasma levels of Hcy and the corresponding protein mixed disulfides increased progressively in HTs, RFs, and HTRFs with respect to control. These changes were correlated with cysteine variations (as cystine and protein-mixed disulfides) but not with glutathione or cysteinylglycine that varied only as disulfides with a similar tendency. Moreover, an alteration in the plasma redox was evidenced by the decrease in thiol/disulfide ratios of cysteine, Hcy, and cysteinylglycine. In all groups, cysteine was directly correlated with Hcy but not with glutathione or cysteinylglycine, which in turn were correlated each other. Therefore levels of plasma cysteine were more linked to Hcy than to metabolism of glutathione. The clinical meaning of cysteine changes remains undefined and requires further study.

Pulse ischemia-dependent submaximal increase in adenosine levels in plasma and in the interstitium is believed to mediate the phenomenon of ischemic preconditioning of the heart, by the interaction with the specific A1 and A3 receptors on myocytes. The aim of the study was to evaluate the effects of chronic oral treatment with dipyridamole (75 mg twice a day for 5 days) in coronary artery disease (CAD) patients with positive echocardiographic stress test with high-dose dipyridamole (DET). We evaluated positivity to DET, adenosine plasma levels in 12 patients treated with dipyridamole in comparison to eight patients treated with placebo. After oral administration of dipyridamole we observed a significant reduction in the number of patients positive to DET (5/12; P=0.02), a pulse increase in adenosine plasma levels (from 220+/-55 to 450+/-70 nmol/l), without any significant haemodynamic effects. Our results suggest that dipyridamole, administered orally at a low dose, but sufficient to increase adenosine plasma level, was able to prevent myocardial ischemia induced by high-dose dipyridamole echo-stress test in CAD patients.