A gain-of-function HCN4 mutant in the HCN domain is responsible for inappropriate sinus tachycardia in a Spanish family.

In a family with inappropriate sinus tachycardia (IST), we identified a mutation (p.V240M) of the hyperpolarization-activated cyclic nucleotide-gated type 4 (HCN4) channel, which contributes to the pacemaker current (If) in human sinoatrial node cells. Here, we clinically study fifteen family members and functionally analyze the p.V240M variant. Macroscopic (IHCN4) and single-channel currents were recorded using patch-clamp in cells expressing human native (WT) and/or p.V240M HCN4 channels. All p.V240M mutation carriers exhibited IST that was accompanied by cardiomyopathy in adults. IHCN4 generated by p.V240M channels either alone or in combination with WT was significantly greater than that generated by WT channels alone. The variant, which lies in the N-terminal HCN domain, increased the single-channel conductance and opening frequency and probability of HCN4 channels. Conversely, it did not modify the channel sensitivity for cAMP and ivabradine or the level of expression at the membrane. Treatment with ivabradine based on functional data reversed the IST and the cardiomyopathy of the carriers. In computer simulations, the p.V240M gain-of-function variant increases If and beating rate and thus explains the IST of the carriers. The results demonstrate the importance of the unique HCN domain in HCN4, which stabilizes the channels in the closed state.

Drug-induced atrial fibrillation. A narrative review of a forgotten adverse effect.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an increased morbidity and mortality. There is clinical evidence that an increasing number of cardiovascular and non-cardiovascular drugs, mainly anticancer drugs, can induce AF either in patients with or without pre-existing cardiac disorders, but drug-induced AF (DIAF) has not received the attention that it might deserve. In many cases DIAF is asymptomatic and paroxysmal and patients recover sinus rhythm spontaneously, but sometimes, DIAF persists, and it is necessary to perform a cardioversion. Furthermore, DIAF is not mentioned in clinical guidelines on the treatment of AF. The risk of DIAF increases in elderly and in patients treated with polypharmacy and with risk factors and comorbidities that commonly coexist with AF. This is the case of cancer patients. Under these circumstances ascribing causality of DIAF to a given drug often represents a clinical challenge. We review the incidence, the pathophysiological mechanisms, risk factors, clinical relevance, and treatment of DIAF. Because of the limited information presently available, further research is needed to obtain a deeper insight into DIAF. Meanwhile, it is important that clinicians are aware of the problem that DIAF represents, recognize which drugs may cause DIAF, and consider the possibility that a drug may be responsible for a new-onset AF episode.

An account on the history of pharmacology in Spain.

Here we present an account on the history of pharmacology in Spain. Pharmacology as an independent science in Europe began with the creation of university chairs. Of particular relevance was the appointment in 1872 of Osswald Shmiedeberg as chairman of an Institute of Pharmacology at the University of Strassbourg, Germany. Teófilo Hernando pioneered in Spain the new emerging pharmacology at the beginning of the XX Century. He made a posdoctoral stay in the laboratory of Schmiedeberg, working on digitalis. In 1912 he won the chair of "Materia Médica y Arte de Recetar" at "Universidad Central of Madrid" (today, "Universidad Complutense de Madrid", UCM). He soon decided to transform such subject to the emerging modern pharmacology, with the teaching of experimental pharmacology in the third course of medical studies and clinical therapeutics (today clinical pharmacology) in the sixth course. This was the status of pharmacology in 1920, supporting the view that Hernando was a pioneer of clinical pharmacology. However, the Spanish Civil War and the II Word War interropted this division of preclinical and clinical pharmacology; only in the 1980's was clinical pharmacolgy partially developed in Spain. From a scientific point of view, Hernando directly trained various young pharmacologists that extended the new science to various Spanish universities. Some of his direct disciples were Benigno Lorenzo Velázquez, Francisco García Valdecasas, Rafael Méndez, Tomás Alday, Gabriel Sánchez de la Cuesta, Dámaso Gutiérrez or Ramón P é rez-Cirera. One of the central research subject was the analysis of the effects of digitalis on the cat and frog heart. In the initiation of the 1970 s pharmacologists trained by those Hernando's students grew throughout various universities and the "Consejo Superior de Investigaciones Científicas" (CSIC). And hence, in 1972 the "Sociedad Española de Farmacología" (SEF) emerged. Later on, in the 1990's the "Sociedad Española de Farmacología Clínica (SEFC) also emerged. The relationship between the two societies is still weak. Out of the vast scope of the pharmacological sciences, Spanish pharmacologists have made relevant contributions in two areas namely, neuropsychopharmacology and cardiovacular pharmacology. Nonetheless, in other areas such as smooth muscle, gastroenterology, pharmacogenetics and hepatic toxicity, Spanish pharmacologists have also made relevant contributions. A succint description of such contributions is made. Finally, some hints on perspectives for the further development of preclinical and clinical pharmacology in Spain, are offered.

EHRA expert consensus document on the management of arrhythmias in frailty syndrome, endorsed by the Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Latin America Heart Rhythm Society (LAHRS), and Cardiac Arrhythmia Society of Southern Africa (CASSA).

There is an increasing proportion of the general population surviving to old age with significant chronic disease, multi-morbidity, and disability. The prevalence of pre-frail state and frailty syndrome increases exponentially with advancing age and is associated with greater morbidity, disability, hospitalization, institutionalization, mortality, and health care resource use. Frailty represents a global problem, making early identification, evaluation, and treatment to prevent the cascade of events leading from functional decline to disability and death, one of the challenges of geriatric and general medicine. Cardiac arrhythmias are common in advancing age, chronic illness, and frailty and include a broad spectrum of rhythm and conduction abnormalities. However, no systematic studies or recommendations on the management of arrhythmias are available specifically for the elderly and frail population, and the uptake of many effective antiarrhythmic therapies in these patients remains the slowest. This European Heart Rhythm Association (EHRA) consensus document focuses on the biology of frailty, common comorbidities, and methods of assessing frailty, in respect to a specific issue of arrhythmias and conduction disease, provide evidence base advice on the management of arrhythmias in patients with frailty syndrome, and identifies knowledge gaps and directions for future research.

An Updated Review on the Role of Non-dihydropyridine Calcium Channel Blockers and Beta-blockers in Atrial Fibrillation and Acute Decompensated Heart Failure: Evidence and Gaps.

PURPOSE: The 2021 European Society of Cardiology guidelines on acute and chronic heart failure (HF) recommend that non-dihydropyridine calcium channel blockers (NDCC) should be avoided in patients with HF with reduced ejection fraction. It also emphasizes that beta-blockers only be initiated in clinically stable, euvolemic patients. Despite these recommendations, NDCC and beta-blockers are often still employed in patients with AF with rapid ventricular response and acute decompensated HF. The relative safety and efficacy of these therapies in this setting is unclear. METHODS: To address the question of the safety and efficacy of NDCC and beta-blockers for acute rate control in decompensated HF, we provide a perspective on the literature of NDCC and beta-blockers in chronic HF with reduced and preserved ejection fraction and AF, including trials on the management of AF with rapid ventricular response with and without HF. RESULTS: Robust data demonstrates mortality benefits when beta-blockers are used in patients with chronic HF with reduced ejection fraction. The data that inform the contraindication of NDCC in HF with reduced ejection fraction are outdated and were not primarily designed to address the efficacy and safety of rate control of AF in patients with HF. Several studies indicate that for acute rate control, NDCC and beta-blockers are both efficacious therapies, especially in the setting of tachycardia-induced cardiomyopathy. CONCLUSION: Future studies are needed to assess the safety and efficacy of beta-blockers and NDCC in both acute and chronic AF with HF with reduced and preserved ejection fraction.

Factors associated with poor prognosis in patients with atrial fibrillation: An emergency department perspective the EMERG-AF study.

OBJECTIVE: We sought to identify the factors associated with a worse prognosis in Emergency Department (ED) patients with atrial fibrillation (AF), crucial information to guide management decisions. METHODS: This is a secondary analysis of a prospective, multicenter, observational cohort of consecutive AF patients attended in 62 EDs in Spain. Clinical variables were collected on enrollment. Follow-up was performed at 30 days and one year. The primary composite outcome was all-cause mortality, major bleeding and/or stroke at one year. Secondary outcomes were each of these components considered separately, plus one-year cardiovascular mortality and the composite outcome at 30 days. RESULTS: We analyzed 1107 patients. The primary outcome occurred in 209 patients (18.9%), one-year all-cause mortality in 151 (13.6%), major bleeding in 47 (4.2%), and stroke in 31 (2.8%). Disability (HR 2.064, 95% CI 1.478-2.882), previous known AF (HR 1.829, 95% CI 1.096-3.051), long duration of the AF episode (HR 1.849, 95% CI 1.052-3.252) and renal failure (HR 2.073, 95% CI 1.433-2.999) were independently associated with the primary outcome, whereas anticoagulation at discharge was inversely associated (HR 0.576, 95% CI 0.415-0.801). Disability was associated with mortality, cardiovascular mortality, and the composite at 30 days, and renal failure with mortality and major bleeding. CONCLUSIONS: Comorbidities like renal failure, long AF duration and disability were related to adverse outcomes and should be decisive to guide management decisions in ED patients with AF. Anticoagulation had a positive impact on prognosis and should be the mainstay of therapy in AF patients attended in ED.

Zfhx3 Transcription Factor Represses the Expression of SCN5A Gene and Decreases Sodium Current Density (INa).

The ZFHX3 and SCN5A genes encode the zinc finger homeobox 3 (Zfhx3) transcription factor (TF) and the human cardiac Na+ channel (Nav1.5), respectively. The effects of Zfhx3 on the expression of the Nav1.5 channel, and in cardiac excitability, are currently unknown. Additionally, we identified three Zfhx3 variants in probands diagnosed with familial atrial fibrillation (p.M1260T) and Brugada Syndrome (p.V949I and p.Q2564R). Here, we analyzed the effects of native (WT) and mutated Zfhx3 on Na+ current (INa) recorded in HL-1 cardiomyocytes. ZFHX3 mRNA can be detected in human atrial and ventricular samples. In HL-1 cardiomyocytes, transfection of Zfhx3 strongly reduced peak INa density, while the silencing of endogenous expression augmented it (from -65.9 ± 8.9 to -104.6 ± 10.8 pA/pF; n ≥ 8, p < 0.05). Zfhx3 significantly reduced the transcriptional activity of human SCN5A, PITX2, TBX5, and NKX25 minimal promoters. Consequently, the mRNA and/or protein expression levels of Nav1.5 and Tbx5 were diminished (n ≥ 6, p < 0.05). Zfhx3 also increased the expression of Nedd4-2 ubiquitin-protein ligase, enhancing Nav1.5 proteasomal degradation. p.V949I, p.M1260T, and p.Q2564R Zfhx3 produced similar effects on INa density and time- and voltage-dependent properties in WT. WT Zfhx3 inhibits INa as a result of a direct repressor effect on the SCN5A promoter, the modulation of Tbx5 increasing on the INa, and the increased expression of Nedd4-2. We propose that this TF participates in the control of cardiac excitability in human adult cardiac tissue.

Tbx20 controls the expression of the KCNH2 gene and of hERG channels.

Long QT syndrome (LQTS) exhibits great phenotype variability among family members carrying the same mutation, which can be partially attributed to genetic factors. We functionally analyzed the KCNH2 (encoding for Kv11.1 or hERG channels) and TBX20 (encoding for the transcription factor Tbx20) variants found by next-generation sequencing in two siblings with LQTS in a Spanish family of African ancestry. Affected relatives harbor a heterozygous mutation in KCNH2 that encodes for p.T152HfsX180 Kv11.1 (hERG). This peptide, by itself, failed to generate any current when transfected into Chinese hamster ovary (CHO) cells but, surprisingly, exerted "chaperone-like" effects over native hERG channels in both CHO cells and mouse atrial-derived HL-1 cells. Therefore, heterozygous transfection of native (WT) and p.T152HfsX180 hERG channels generated a current that was indistinguishable from that generated by WT channels alone. Some affected relatives also harbor the p.R311C mutation in Tbx20. In human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), Tbx20 enhanced human KCNH2 gene expression and hERG currents (IhERG) and shortened action-potential duration (APD). However, Tbx20 did not modify the expression or activity of any other channel involved in ventricular repolarization. Conversely, p.R311C Tbx20 did not increase KCNH2 expression in hiPSC-CMs, which led to decreased IhERG and increased APD. Our results suggest that Tbx20 controls the expression of hERG channels responsible for the rapid component of the delayed rectifier current. On the contrary, p.R311C Tbx20 specifically disables the Tbx20 protranscriptional activity over KCNH2 Therefore, TBX20 can be considered a KCNH2-modifying gene.

Cardiac electrical defects in progeroid mice and Hutchinson-Gilford progeria syndrome patients with nuclear lamina alterations.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disease caused by defective prelamin A processing, leading to nuclear lamina alterations, severe cardiovascular pathology, and premature death. Prelamin A alterations also occur in physiological aging. It remains unknown how defective prelamin A processing affects the cardiac rhythm. We show age-dependent cardiac repolarization abnormalities in HGPS patients that are also present in the Zmpste24-/- mouse model of HGPS. Challenge of Zmpste24-/- mice with the ß-adrenergic agonist isoproterenol did not trigger ventricular arrhythmia but caused bradycardia-related premature ventricular complexes and slow-rate polymorphic ventricular rhythms during recovery. Patch-clamping in Zmpste24-/- cardiomyocytes revealed prolonged calcium-transient duration and reduced sarcoplasmic reticulum calcium loading and release, consistent with the absence of isoproterenol-induced ventricular arrhythmia. Zmpste24-/- progeroid mice also developed severe fibrosis-unrelated bradycardia and PQ interval and QRS complex prolongation. These conduction defects were accompanied by overt mislocalization of the gap junction protein connexin43 (Cx43). Remarkably, Cx43 mislocalization was also evident in autopsied left ventricle tissue from HGPS patients, suggesting intercellular connectivity alterations at late stages of the disease. The similarities between HGPS patients and progeroid mice reported here strongly suggest that defective cardiac repolarization and cardiomyocyte connectivity are important abnormalities in the HGPS pathogenesis that increase the risk of arrhythmia and premature death.

New Therapeutic Approaches for the Treatment of Hyperkalemia in Patients Treated with Renin-Angiotensin-Aldosterone System Inhibitors.

Hyperkalemia (serum potassium > 5.5 mEq/L) is a common clinical problem in patients with chronic kidney disease, hypertension, diabetes, and heart failure. It can result from increased K+ intake, impaired distribution between intracellular and extracellular spaces, and most frequently, decreased renal excretion. Patients at the highest risk of hyperkalemia are treated with renin-angiotensin-aldosterone system inhibitors (RAASIs) as they improve cardiovascular and renal outcomes and are strongly recommended in clinical guidelines. However, RAASIs cause or increase the risk of hyperkalemia, a key limitation to fully titrate RAASIs in patients who are most likely to benefit from treatment. Until recently, drugs for the treatment of hyperkalemia presented limited efficacy and/or safety concerns and there was an unmet need of new drugs to control hyperkalemia while maintaining RAASI therapy. We provide an overview of the mechanisms involved in K+ homeostasis and the epidemiology and management of hyperkalemia as a complication in cardiovascular patients and, finally, analyze the efficacy and safety of two new polymer-based, non-systemic agents, patiromer calcium and sodium zirconium cyclosilicate (ZS-9), designed to increase fecal K+ loss and to normalize elevated serum K+ levels and chronically maintain K+ homeostasis in hyperkalemic patients treated with RAASIs.

Benefits of Emergency Departments' Contribution to Stroke Prophylaxis in Atrial Fibrillation: The EMERG-AF Study (Emergency Department Stroke Prophylaxis and Guidelines Implementation in Atrial Fibrillation).

BACKGROUND AND PURPOSE: Long-term benefits of initiating stroke prophylaxis in the emergency department (ED) are unknown. We analyzed the long-term safety and benefits of ED prescription of anticoagulation in atrial fibrillation patients. METHODS: Prospective, multicenter, observational cohort of consecutive atrial fibrillation patients was performed in 62 Spanish EDs. Clinical variables and thromboprophylaxis prescribed at discharge were collected at inclusion. Follow-up at 1 year post-discharge included data about thromboprophylaxis and its complications, major bleeding, and death; risk was assessed with univariate and bivariate logistic regression models. RESULTS: We enrolled 1162 patients, 1024 (88.1%) at high risk according to CHA2DS2-VASc score. At ED discharge, 935 patients (80.5%) were receiving anticoagulant therapy, de novo in 237 patients (55.2% of 429 not previously treated). At 1 year, 48 (4.1%) patients presented major bleeding events, and 151 (12.9%) had died. Anticoagulation first prescribed in the ED was not related to major bleeding (hazard ratio, 0.976; 95% confidence interval, 0.294-3.236) and was associated with a decrease in mortality (hazard ratio, 0.398; 95% confidence interval, 0.231-0.686). Adjusting by the main clinical and sociodemographic characteristics, concomitant antiplatelet treatment, or destination (discharge or admission) did not affect the results. CONCLUSIONS: Prescription of anticoagulation in the ED does not increase bleeding risk in atrial fibrillation patients at high risk of stroke and contributes to decreased mortality.

Vascular and Central Activation of Peroxisome Proliferator-Activated Receptor-ß Attenuates Angiotensin II-Induced Hypertension: Role of RGS-5.

Activation of peroxisome proliferator-activated receptor-ß/δ (PPARß) lowers blood pressure in genetic and mineralocorticoid-induced hypertension. Regulator of G-protein-coupled receptor signaling 5 (RGS5) protein, which interferes in angiotensin II (AngII) signaling, is a target gene to PPARß The aim of the present study was to examine whether PPARß activation in resistance arteries and brain tissues prevents the elevated blood pressure in AngII-induced hypertension and evaluate the role of RGS5 in this effect. C57BL/6J male mice were divided into five groups (control mice, PPARß agonist [4-[[[2-[3-Fluoro-4-(trifluoromethyl)phenyl]-4-methyl-5-thiazolyl]methyl]thio]-2-methylphenoxy]acetic acid (GW0742)-treated mice AngII-infused mice, GW0742-treated AngII-infused mice, and AngII-infused mice treated with GW0742 plus PPARß antagonist 3-[[[2-Methoxy-4-(phenylamino)phenyl]amino]sulfonyl]-2-thiophenecarboxylic acid methyl ester (GSK0660)) and were followed for 3 weeks. GW0742 prevented the increase in both arterial blood pressure and plasma noradrenaline levels and the higher reduction of blood pressure after ganglionic blockade, whereas it reduced the mesenteric arterial remodeling and the hyper-responsiveness to vasoconstrictors (AngII and endothelin-1) in AngII-infused mice. These effects were accompanied by an inhibition of NADPH oxidase expression and activity in the brain. Gene expression profiling revealed a marked loss of brainstem and vascular RGS5 in AngII-infused mice, which was restored by GW0742. GW0742-induced effects were abolished by GSK0660. Small interfering RNA targeting RGS5 caused augmented contractile response to AngII in resistance mesenteric arteries and blunted the inhibitory effect of GW0742 on this response. In conclusion, GW0742 exerted antihypertensive effects, restoring sympathetic tone and vascular structure and function in AngII-infused mice by PPARß activation in brain and vessels inhibiting AngII signaling as a result of RGS5 upregulation.