Prolongation of the QT interval and ventricular tachycardia in patients treated with arsenic trioxide for acute promyelocytic leukemia

Zebrafish as an innovative model for exploring cardiovascular disease induction mechanisms and novel therapeutic interventions: a molecular insight

Cardiovascular disease (CVD) is a common cardiac disorder that leads to heart attacks, strokes, and heart failure. It is primarily characterized by conditions that impact the heart and blood arteries, including peripheral artery disease, arrhythmias, atherosclerosis, myocardial ischemia, congenital heart abnormalities, heart failure, rheumatic heart disease, hypertension, and cardiomyopathies. These conditions are mainly effect the heart and blood vessels, causing blockages or weakened pumping, due to severe hereditary and environmental factors. The frequency of CVD is rising significantly as life expectancy increases. Despite this, no effective treatment or management for its symptoms has been found. One of the most difficult obstacles to overcome, is finding a suitable animal model for drug screening and drug development. Although rodents, mice, swine, and mammals serve as the basis for most animal models of cardiovascular disease, no model accurately captures the epidemiology of the condition. Zebrafish (Danio rerio) have drawn the interest of the international scientific community due to certain shortcomings of the previously discussed animal models because they are smaller, less costly, and have an incredibly high rate of reproduction. This review article emphasizes the significance of using zebrafish as an animal model to investigate the possible facets of cardiovascular disease. Moreover, the ultimate purpose of this review article is to establish the advantages of employing zebrafish over other animal models and to investigate the boundaries of using zebrafish to study human disease. Furthermore, the mechanisms of cardiovascular diseases induction in zebrafish were covered to improve understanding for readers. Finally, the analysis of cardiotoxicity using Zebra fish model, is also explained. In order to stop the health index from deteriorating, the current study also covers some innovative, effective, and relatively safer treatments for treatment and management of cardiotoxicity.

The involvement and therapeutic potential of lncRNA Kcnq1ot1/miR-34a-5p/Sirt1 pathway in arsenic trioxide-induced cardiotoxicity

BACKGROUND/AIMS

Arsenic trioxide (ATO) is the first-line therapeutic drug for acute promyelocytic leukemia. However, the cardiotoxicity of ATO limits its clinical application. This study aims to explore the long noncoding RNA (lncRNA) involved molecular mechanism in ATO-induced cardiotoxicity and to identify available prevention strategies.

METHODS

ATO was administered to mice or primary cultured mouse cardiomyocytes. Small interfering RNA targeting lncRNA Kcnq1ot1 (si-Kcnq1ot1) was used to knockdown lncRNA Kcnq1ot1. MiR-34a-5p mimic and antisense morpholino oligonucleotide targeting miR-34a-5p (AMO-34a-5p) were used to upregulate and downregulate the expression of miR-34a-5p, respectively. TUNEL staining was conducted to detect cell DNA damage. Flow cytometry assay was used to detect cell apoptosis. Western blot was conducted to detect Bcl-2, Bax and Sirt1 protein expression. Real-time PCR was used to detect lncRNA Kcnq1ot1, miR-34a-5p, and Sirt1 mRNA expression. Dual-luciferase reporter assay was performed to validate the predicted binding site.

RESULTS

ATO induced apoptosis in cardiomyocytes both in vivo and in vitro. Simultaneously, the expression of lncRNA Kcnq1ot1 and Sirt1 was downregulated, and miR-34a-5p was upregulated. MiR-34a-5p has binding sites with lncRNA Kcnq1ot1 and Sirt1. Knockdown of lncRNA Kcnq1ot1 induced apoptosis of cardiomyocytes, with increased miR-34a-5p and decreased Sirt1 expression. Inhibition of miR-34a-5p attenuated si-Kcnq1ot1-induced apoptosis in cardiomyocytes. Therefore, the lncRNA Kcnq1ot1/miR-34a-5p/Sirt1 signaling pathway is involved in ATO-induced cardiotoxicity. Propranolol alleviated ATO-induced apoptosis in cardiomyocytes both in vivo and in vitro, which was related to the lncRNA Kcnq1ot1/miR-34a-5p/Sirt1 signaling pathway.

CONCLUSION

The lncRNA Kcnq1ot1/miR-34a-5p/Sirt1 pathway is involved in ATO-induced cardiotoxicity. Propranolol can attenuate ATO-induced cardiotoxicity at least partially through the lncRNA Kcnq1ot1/miR-34a-5p/Sirt1 pathway. Combined administration with propranolol may be a new strategy for alleviating the cardiotoxicity of ATO.

Emerging roles of circular RNAs in cancer therapy-induced cardiotoxicity

Cancer therapy-induced cardiotoxicity (CTIC) is an important cause of death in cancer survivors which often results in the withdrawal or discontinuation of drugs. The underlying mechanisms of CTIC remain unclear. Circular RNAs (circRNAs) are a class of non-coding regulatory RNA molecules which have emerged in recent years. They are generated by back splicing and have powerful biological functions, including transcription and splicing, isolating or building macromolecular scaffolds to interfere with microRNA activity and signaling pathways, and acting as templates for translation. Moreover, circRNAs demonstrate high abundance and significant stability. CircRNAs can be used as novel biomarkers because they often function in a cell-type and tissue-specific manner. CircRNAs have attracted increasing attention in cardiovascular disease research, and recent studies exploring the role of circRNAs in CTIC have had promising results. This review will summarize the current understanding of circRNAs' biogenesis, regulation and function. Their clinical potential as biomarkers, therapeutic agents and drug targets will also be explored.

Long-term retrospective study of retinoic acid combined with arsenic and chemotherapy for acute promyelocytic leukemia

Chemotherapy, all-trans retinoic acid (ATRA), and arsenic are effective options for acute promyelocytic leukemia (APL). We conducted a 20-year retrospective analysis of newly diagnosed (ND) APL patients treated with arsenic, ATRA and mitoxantrone. After achieving complete remission (CR), patients received 3-5 cycles of chemotherapy followed by AS4S4 maintenance for 3 years. Eighty-eight ND APL patients were treated with either oral AS4S4 (n = 42) or arsenic trioxide (ATO) (n = 46). The 8-year overall survival (OS) rate was 100% in the AS4S4 group and 90% in the ATO group. The disease-free survival (DFS) rates were 100% and 87.1% (p = 0.027), respectively. Patients in the ATO group had more side effects. A subsequent cohort of 33 ND APL patients received triple therapy with oral AS4S4, ATRA, and chemotherapy. The 13-year OS and DFS rates were 100% and 90.9%. Our long-term analyses show that APL patients with oral AS4S4 had better outcomes compared to ATO, with no need for hospitalization.

Poison With a Purpose: A Case Report on Arsenic Cardiotoxicity and Obesity

Acute promyelocytic leukemia (APL) is a form of leukemia in which there is an arrest of the maturation of the myeloid lineage at the promyelocyte stage. Although there is high early mortality due to coagulopathy, APL is now a curable disease with the use of arsenic trioxide (ATO) and all-trans-retinoic acid (ATRA). Arsenic is weight-based for the treatment of APL, and many toxicities are dose-dependent, although there are no guidelines regarding dosing adjustments for obese patients. We present a case of a 34-year-old male with obesity and APL who developed arsenic-induced QTc prolongation and symptomatic sinus tachycardia while receiving treatment. Further research is needed to guide appropriate dosing for obese patients to determine if ideal body weight dosing is able to provide similar cure rates with fewer adverse events.

Drug-Induced QT Prolongation and Torsade de Pointes in Spontaneous Adverse Event Reporting: A Retrospective Analysis Using the Japanese Adverse Drug Event Report Database (2004-2021)

BACKGROUND

Drugs with new mechanisms of action are continually being developed, but it is difficult to capture whether a drug induces QT prolongation/torsade de pointes (TdP) in preclinical and preapproval clinical trials.

OBJECTIVE

To evaluate drugs associated with drug-induced QT prolongation/TdP using a real-world database in Japan.

PATIENTS AND METHODS

A search was performed in the Japanese Adverse Drug Event Report (JADER) database for QT prolongation and TdP. The reporting odds ratio (ROR) was calculated to identify potential drug-induced QT prolongation/TdP association.

RESULTS

Among the reported 4,326,484 data entries, 3410 patients exhibited QT prolongation/TdP (2707 with QT prolongation, 703 with TdP) with the suspected drugs. Of these patients, 53.9% were females. The highest occurrence was in the 70- to 79-year-old age group (24.7%). The most common types of drugs involved were cardiovascular drugs, central nervous system (CNS) drugs, anticancer drugs, and anti-infective drugs; the rate of overdose was reportedly very low at 1.6%. The highest adjusted RORs were observed for nifekalant (351.41, 95% confidence interval (CI) 235.85-523.59), followed by vandetanib (182.55, 95% CI 108.11-308.24), evocalcet (181.59, 95% CI 132.96-248.01), bepridil (160.37, 95% CI 138.17-186.13), diarsenic trioxide (79.43, 95% CI 63.98-98.62), and guanfacine (78.29, 95% CI 58.51-104.74). Among the drugs launched in Japan during the last decade, vandetanib had the highest adjusted RORs.

CONCLUSIONS

This study using the JADER database showed that antiarrhythmic drugs, calcium-sensing receptor agonists, small-molecule targeted anticancer drugs, and CNS drugs are associated with QT prolongation/TdP. Further pharmacoepidemiological studies, such as cohort studies using large databases, are needed to prove these causal relationships.

Palpitations in the Cancer Patient

Cancer and cardiovascular diseases (CVD) are among the leading causes of death worldwide. In response to the growing population of cancer patients and survivors with CVD, the sub-specialty of cardio-oncology has been developed to better optimise their care. Palpitations are one of the most common presenting complaints seen in the emergency room or by the primary care provider or cardiologist. Palpitations are defined as a rapid pulsation or abnormally rapid or irregular beating of the heart and present a complex diagnostic entity with no evidence-based guidelines currently available. Palpitations are a frequent occurrence in people with cancer, and investigations and treatment are comparable to that in the general population although there are some nuances. Cancer patients are at a higher risk of arrhythmogenic causes of palpitations and non-arrhythmogenic causes of palpitations. This review will appraise the literature with regards to the development and management of palpitations in the cancer patient.

Toward a broader view of mechanisms of drug cardiotoxicity

Cardiotoxicity, defined as toxicity that affects the heart, is one of the most common adverse drug effects. Numerous drugs have been shown to have the potential to induce lethal arrhythmias by affecting cardiac electrophysiology, which is the focus of current preclinical testing. However, a substantial number of drugs can also affect cardiac function beyond electrophysiology. Within this broader sense of cardiotoxicity, this review discusses the key drug-protein interactions known to be involved in cardiotoxic drug response. We cover adverse effects of anticancer, central nervous system, genitourinary system, gastrointestinal, antihistaminic, anti-inflammatory, and anti-infective agents, illustrating that many share mechanisms of cardiotoxicity, including contractility, mitochondrial function, and cellular signaling.

Recent development of chromogenic and fluorogenic chemosensors for the detection of arsenic species: Environmental and biological applications

Due to biological and environmental significance of highly toxic arsenic species, the design, synthesis and development of chemosensors for arsenic species has been a very active research field in recent times. In this review, we summarize recent works on the sensing mechanisms employed by fluorometric/colorimetric chemosensors and their applications in arsenic detection. Various types of sensing strategies can be categorized into six types including (i) chemosensors based on hydrogen bonding interactions; (ii) aggregation induced emission (AIE) based chemosensors; (iii) chemodosimetric approach (reaction-based chemosensors); (iv) metal coordination-based sensing strategy; (v) chemosensors based on metal complex displacement approach and (vi) metal complex as chemosensor. All these sensing strategies are very much simple and sensitive for use in the design of arsenic selective chromogenic and fluorogenic probes.

ECG Markers of Cardiovascular Toxicity in Adult and Pediatric Cancer Treatment

When a cardiologist is asked to evaluate the cardiac toxic effects of chemotherapy, he/she can use several tools: ECG, echocardiography, coronary angiography, ventriculography, and cardiac MRI. Of all these, the fastest and easiest to use is the ECG, which can provide information on the occurrence of cardiac toxic effects and can show early signs of subclinical cardiac damage. These warning signs are the most desired to be recognized by the cardiologist, because the dose of chemotherapeutics can be adjusted so that the clinical side effects do not occur, or the therapy can be stopped in time, before irreversible side effects. This review addresses the problem of early detection of cardiotoxicity in adult and pediatric cancer treatment, by using simple ECG recordings.

Resurrection of Oral Arsenic Trioxide for Treating Acute Promyelocytic Leukaemia: A Historical Account From Bedside to Bench to Bedside

Various forms of arsenic were used in China and elsewhere for over 5,000 years. Following the initial success of intravenous arsenic trioxide (i.v. As₂O₃), we revived an oral formulation of pure As₂O₃ in 1998 for the treatment of acute promyelocytic leukemia (APL). We were the first to produce a 1 mg/ml oral-As₂O₃ solution and showed that it had comparable bioavailability to i.v. As₂O₃. Moreover, we also reported that intracellular arsenic concentrations were considerably higher than the corresponding plasma values. Our oral-As₂O₃ was patented internationally and registered in Hong Kong for the treatment of APL. Safety, tolerability and clinical efficacy was confirmed in long-term follow-up studies. We have extended the use of oral-As₂O₃ to frontline induction of newly diagnosed APL. With these findings, we are moving toward an era of completely oral and chemotherapy-free management of APL.

[Proarrhythmic adverse effects of nonarrhythmic drugs]

Acquired QT prolongation is almost exclusively the result of inhibition of the potassium channel Ikr. Especially hospitalized patients have a high risk to suffer from Torsade de points (TdP). Therefore, any prescription of drugs with the potential for QT prolongation should involve the consideration of the necessity of the agent and interaction with other QT prolonging drugs. The website www.crediblemed.com helps to identify the risk for TdP of each drug. During drug prescription, it is necessary to monitor QTc with regular ECGs; QTc prolongation >500 ms or QTc increase >60 ms should trigger end of drug administration followed by monitoring of the patient according to the individual risk for TdP.

An Overview on Arsenic Trioxide-Induced Cardiotoxicity

Arsenic trioxide (ATO) is among the first-line chemotherapeutic drugs used in oncological practice. It has shown substantial efficacy in treating patients with relapsed or refractory acute promyelocytic leukaemia. The clinical use of ATO is hampered due to cardiotoxicity and hence many patients are precluded from receiving this highly effective treatment. An alternative to this would be to use any drug that can ameliorate the cardiotoxic effects and allow exploiting the full therapeutic potential of ATO, with considerable impact on cancer therapy. Generation of reactive oxygen species is involved in a wide range of human diseases, including cancer, cardiovascular, pulmonary and neurological disorders. Hence, agents with the ability to protect against these reactive species may be therapeutically useful. The present review focuses on the beneficial as well as harmful effects of arsenic and ATO, the mechanisms underlying ATO toxicity and the possible ways that can be adopted to circumvent ATO-induced toxicity.

Leveraging genetic interactions for adverse drug-drug interaction prediction

In light of increased co-prescription of multiple drugs, the ability to discern and predict drug-drug interactions (DDI) has become crucial to guarantee the safety of patients undergoing treatment with multiple drugs. However, information on DDI profiles is incomplete and the experimental determination of DDIs is labor-intensive and time-consuming. Although previous studies have explored various feature spaces for in silico screening of interacting drug pairs, their use of conventional cross-validation prevents them from achieving generalizable performance on drug pairs where neither drug is seen during training. Here we demonstrate for the first time targets of adversely interacting drug pairs are significantly more likely to have synergistic genetic interactions than non-interacting drug pairs. Leveraging genetic interaction features and a novel training scheme, we construct a gradient boosting-based classifier that achieves robust DDI prediction even for drugs whose interaction profiles are completely unseen during training. We demonstrate that in addition to classification power—including the prediction of 432 novel DDIs—our genetic interaction approach offers interpretability by providing plausible mechanistic insights into the mode of action of DDIs.

Adverse drug-drug interactions are adverse side effects caused by taking two or more drugs together. As co-prescription of multiple drugs becomes an increasingly prevalent practice, affecting 42.2% of Americans over 65 years old, adverse drug-drug interactions have become a serious safety concern, accounting for over 74,000 emergency room visits and 195,000 hospitalizations each year in the United States alone. Since experimental determination of adverse drug-drug interactions is labor-intensive and time-consuming, various machine learning-based computational approaches have been developed for predicting drug-drug interactions. Considering the fact that drugs effect through binding and modulating the function of their targets, we have explored whether drug-drug interactions can be predicted from the genetic interaction between the gene targets of two drugs, which characterizes the unexpected fitness effect when two genes are simultaneously knocked out. Furthermore, we have built a fast and robust classifier that achieves accurate prediction of adverse drug-drug interactions by incorporating genetic interaction and several other types of widely used features. Our analyses suggest that genetic interaction is an important feature for our prediction model, and that it provides mechanistic insight into the mode of action of drugs leading to drug-drug interactions.

Fucoidan⁻Fucoxanthin Ameliorated Cardiac Function via IRS1/GRB2/ SOS1, GSK3β/CREB Pathways and Metabolic Pathways in Senescent Mice

The effects of low molecular weight fucoidan (LMWF) in combination with high-stability fucoxanthin (HSFUCO) on cardiac function and the metabolic pathways of aging mice (Mus musculus) were investigated. We demonstrated that LMWF and HSFUCO could improve cardiac function in aging mice. Aging mice were treated with LMWF and HSFUCO, either on their own or in combination, on 28 consecutive days. Electrocardiography and whole-cell patch-clamp were used to measure QT interval and action potential duration (APD) of the subjects. Cardiac tissue morphology, reactive oxygen species, and Western blot were also applied. Ultra-high-performance liquid chromatography⁻quadrupole time-of-flight (UPLC-QTOF) mass spectrometry was used for investigating metabolic alterations. The use of LMWF and HSFUCO resulted in improvements in both ventricular rhythms (QT and APD). Treatment with fucoidan and fucoxanthin reduced the expression levels of SOS1 and GRB2 while increasing GSK3β, CREB and IRS1 proteins expression in the aging process. Three main metabolic pathways, namely the TCA cycle, glycolysis, and steroid hormone biosynthesis, were highly enriched in the pathway enrichment analysis. When taken together, the LMWF and HSFUCO treatment improved both the ventricular rhythm and the muscular function of aging subjects by interfering with the metabolism and gene function.

Attempted suicide by poisoning of self-prepared arsenic trioxide solution

Introduction:

Arsenic is a traditional poison that has a history extending back to ancient times.

Case presentation:

A 43-year-old male presented to our Emergency Department 50 min after ingestion of 300 mL self-prepared arsenic trioxide solution (砒霜). He produced the solution from heating xionghuang (雄黃), an arsenic sulfide mineral (As4S4) which is a Chinese herb, for academic purposes a few years ago.

Discussion:

Supportive care including fluid replacement and decontamination with gastric lavage and chelation therapy with intravenous dimercaptopropanesulphonate sodium was given to patient. Spot urine arsenic to creatinine ratio significantly decreased from 343,124 nmol/mmol (day 3) to 7116 nmol/mmol (day 5). He had an uneventful course without any neurological deficit.

Conclusions:

Treatment of acute arsenic poisoning includes supportive care, decontamination, and chelation therapy. DMPS is an antidote for arsenic poisoning and its use should be directed by clinical status and urinary arsenic excretion.

PM2.5 induced cardiac hypertrophy via CREB/GSK3b/SOS1 pathway and metabolomics alterations

The particle matter with diameter less 2.5μm (PM2.5) easier to adsorb toxic substance, and interfere with pulmonary gas exchange. In this study, cardioprotective effects of low molecular weight (LMW) fucoidan in cardiac hypertrophy subjects induced by PM2.5 exposure was conducted by measuring QT interval, Blood pressure, cardiac structure, metabolites and proteins expression in different organs. After PM2.5 exposure, increase in blood pressure, abnormal cardiac function (Prolongation of Action Potential Duration and QT Interval), and structral remodeling (cardiac hypertrophy and fibrosis) were recorded. Fucoidan supplement in consecutive 28 days can reduce the damage to myocardial injury caused by PM2.5. Clearance effect of fucoidan in serum, heart, kidney, lung and liver was found due to organic and inorganic compounds reduced SOS1, CREB, GSK3b, and GRB2 protein level were changed under PM2.5 exposure. Whereas, only CREB level was reduced after fucoidan treatment. Metabolic alteration was also determined that PM2.5 severely damage cardiac tissue and compromise its function. After treatment with fucoidan, the cardiac function was significantly recovered. Our finding demonstrated that LMW could enhance the cardiac status of mice with PM2.5 exposures by rescued QT interval prolongation, action potential and cardiac hypertrophy, and cardiac fibrosis decline.

Role of non-coding RNAs in cardiotoxicity of chemotherapy

The long-time paradoxical situation of non-coding RNAs (ncRNAs) has been terminated for they emerge as executive at full spectrum of gene expression and translation. More recently, it has been demonstrated that some ncRNAs apparently are associated with chemotherapy, causing cardiotoxicity, which taint long-term recovery of patients in growing body of evidence. The current review focused on up-to-date knowledge on regulation change and molecular signaling of ncRNAs, at mean time evaluate their potentials as diagnostic biomarkers or therapeutic targets to monitor and protect cardio function.

Mechanism of As2O3-Induced Action Potential Prolongation and Using hiPS-CMs to Evaluate the Rescue Efficacy of Drugs With Different Rescue Mechanism

Arsenic trioxide (As2O3) has been verified as a breakthrough in the management of acute promyelocytic leukemia in recent decades. However, cardiotoxicity, especially long QT syndrome (LQTS) has become the most important issue during As2O3 treatment. The characterized mechanisms behind this adverse effect are inhibition of cardiac hERG channel trafficking and increase of cardiac calcium currents. In our study, we found a new pathway underlying As2O3-induced cardiotoxicity that As2O3 accelerates lysosomal degradation of hERG on plasma membrane after using brefeldin A (BFA) to block protein trafficking. Then we explored pharmacological rescue strategies on As2O3-induced LQTS, and found that 4 therapeutic agents exert rescue efficacy via 3 different pathways: fexofenadine and astemizole facilitate hERG trafficking via promotion of channel-chaperone formation after As2O3 incubation; ranolazine slows hERG degradation in the presence of As2O3; and resveratrol shows significant attenuation on calcium current increase triggered by As2O3. Moreover, we used human-induced pluripotent stem cell derived cardiomyocytes (hiPS-CMs) to evaluate the rescue effects of the above agents on As2O3-induced prolongation of action potential duration (APD) and demonstrated that fexofenadine and resveratrol significantly ameliorate the prolonged APD. These observations suggested that pharmacological chaperone like fexofenadine and resveratrol might have the potential to protect against the cardiotoxicity of As2O3.

Incidence, Diagnosis, and Management of QT Prolongation Induced by Cancer Therapies: A Systematic Review

Background

The cardiovascular complications of cancer therapeutics are the focus of the burgeoning field of cardio‐oncology. A common challenge in this field is the impact of cancer drugs on cardiac repolarization (ie, QT prolongation) and the potential risk for the life‐threatening arrhythmia torsades de pointes. Although QT prolongation is not a perfect marker of arrhythmia risk, this has become a primary safety metric among oncologists. Cardiologists caring for patients receiving cancer treatment should become familiar with the drugs associated with QT prolongation, its incidence, and appropriate management strategies to provide meaningful consultation in this complex clinical scenario.

Methods and Results

In this article, we performed a systematic review (using Preferred Reporting Items of Systematic Reviews and Meta‐Analyses (PRISMA) guidelines) of commonly used cancer drugs to determine the incidence of QT prolongation and clinically relevant arrhythmias. We calculated summary estimates of the incidence of all and clinically relevant QT prolongation as well as arrhythmias and sudden cardiac death. We then describe strategies to prevent, identify, and manage QT prolongation in patients receiving cancer therapy. We identified a total of 173 relevant publications. The weighted incidence of any corrected QT (QTc) prolongation in our systematic review in patients treated with conventional therapies (eg, anthracyclines) ranged from 0% to 22%, although QTc >500 ms, arrhythmias, or sudden cardiac death was extremely rare. The risk of QTc prolongation with targeted therapies (eg, small molecular tyrosine kinase inhibitors) ranged between 0% and 22.7% with severe prolongation (QTc >500 ms) reported in 0% to 5.2% of the patients. Arrhythmias and sudden cardiac death were rare.

Conclusions

Our systematic review demonstrates that there is variability in the incidence of QTc prolongation of various cancer drugs; however, the clinical consequence, as defined by arrhythmias or sudden cardiac death, remains rare.

Chronic drug-induced effects on contractile motion properties and cardiac biomarkers in human induced pluripotent stem cell-derived cardiomyocytes

BACKGROUND AND PURPOSE

In the pharmaceutical industry risk assessments of chronic cardiac safety liabilities are mostly performed during late stages of preclinical drug development using in vivo animal models. Here, we explored the potential of human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) to detect chronic cardiac risks such as drug-induced cardiomyocyte toxicity.

EXPERIMENTAL APPROACH

Video microscopy-based motion field imaging was applied to evaluate the chronic effect (over 72 h) of cardiotoxic drugs on the contractile motion of hiPS-CMs. In parallel, the release of cardiac troponin I (cTnI), heart fatty acid binding protein (FABP3) and N-terminal pro-brain natriuretic peptide (NT-proBNP) was analysed from cell medium, and transcriptional profiling of hiPS-CMs was done at the end of the experiment.

KEY RESULTS

Different cardiotoxic drugs altered the contractile motion properties of hiPS-CMs together with increasing the release of cardiac biomarkers. FABP3 and cTnI were shown to be potential surrogates to predict cardiotoxicity in hiPS-CMs, whereas NT-proBNP seemed to be a less valuable biomarker. Furthermore, drug-induced cardiotoxicity produced by chronic exposure of hiPS-CMs to arsenic trioxide, doxorubicin or panobinostat was associated with different profiles of changes in contractile parameters, biomarker release and transcriptional expression.

CONCLUSION AND IMPLICATIONS

We have shown that a parallel assessment of motion field imaging-derived contractile properties, release of biomarkers and transcriptional changes can detect diverse mechanisms of chronic drug-induced cardiac liabilities in hiPS-CMs. Hence, hiPS-CMs could potentially improve and accelerate cardiovascular de-risking of compounds at earlier stages of drug discovery.

LINKED ARTICLES

This article is part of a themed section on New Insights into Cardiotoxicity Caused by Chemotherapeutic Agents. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.21/issuetoc.

A long-range emissive mega-Stokes inorganic–organic hybrid material with peripheral carboxyl functionality for As(v) recognition and its application in bioimaging

We demonstrate a strategy for the recognition of As⁵⁺ in aqueous solution using a red-emissive probe based on a perylene–Cu²⁺ ensemble decorated with peripheral free carboxyl functionality.

Current first- and second-line treatment options in acute promyelocytic leukemia

Outcome of acute promyelocytic leukemia (APL) has remarkably improved during the last 30 years, especially after the identification of PML-RARA oncogene as a key in the pathogenesis of APL and all-trans retinoic acid as therapeutic agent. Arsenic trioxide has been recently demonstrated to be the most effective single antileukemic agent and it has also showed synergistic action when combined with all-trans retinoic acid, decreasing relapse rate especially in low/intermediate-risk settings. Therapeutic advances led to complete remission rates of more than 90%, modifying disease history. In relapse setting, arsenic trioxide-based regimens showed efficacy for the achievement of second molecular complete remission. The most challenging issue in APL management remains the significant early deaths rate, nowadays the principal reason for treatment failure.

Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias

Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended.

Differential mechanistic investigation of protective effects from imperatorin and sec-O-glucosylhamaudol against arsenic trioxide-induced cytotoxicity in vitro

BACKGROUND AND PURPOSE

The clinical use of arsenic trioxide (As₂O₃) for treating acute promyelocytic leukemia (APL) is limited due to its severe cardiotoxicity. The possible mechanisms of As₂O₃-induced cardiotoxicity include DNA fragmentation, reactive oxygen species (ROS) generation, cardiac ion channel changes and apoptosis. The present study is designed to investigate the protective effects of imperatorin and sec-O-glucosylhamaudol and to explore their mechanistic involvement in As₂O₃-induced cytotoxicity.

EXPERIMENTAL METHODS

Cell viability assay, Lactate dehydrogenase (LDH) release, Acridine orange/ethidium bromide (AO/EB) double staining, Caspase-3 activity assay, ROS generation, cellular calcium levels, mRNA expression levels by qRT-PCR and protein expression levels by Western blotting were measured in H9c2 cells in combination with As₂O₃ and imperatorin or sec-O-glucosylhamaudol.

KEY RESULTS

We observed that H9c2 cells treated with imperatorin or sec-O-glucosylhamaudol were more resistant to As₂O₃-induced cell death. Both imperatorin and sec-O-glucosylhamaudol reduced H9c2 cell apoptosis, but both imperatorin and sec-O-glucosylhamaudol had no effects on Caspase-3 activity and intracellular calcium accumulation. Furthermore, imperatorin was capable of suppressing ROS generation, while sec-O-glucosylhamaudol did not show this effect. Moreover, imperatorin and sec-O-glucosylhamaudol triggered Nrf2 activation, which resulted in upregulation of downstream phase II metabolic enzymes and antioxidant protein/enzyme, probably offering cellular protection to As₂O₃-induced cardiotoxicity via the Nrf2 signal pathway.

CONCLUSIONS AND IMPLICATIONS

Imperatorin and sec-O-glucosylhamaudol can ameliorate As₂O₃-induced cytotoxicity and apoptosis in H9c2 cells, the mechanisms probably related to antioxidation. As₂O₃ in combination with imperatorin or sec-O-glucosylhamaudol could be considered as a novel strategy to expand the clinical application of As₂O₃.

Overview of drug therapy for multiple myeloma

Background. Multiple myeloma accounts for 10% of all haematologic malignancies worldwide. In Europe, over 10 000 new cases and nearly 8000 deaths were attributed to multiple myeloma in 2000. Unlike other malignancies, in which surgery and radiation are important treatment modalities, myeloma is exclusively treated with stem cell transplantation and drug therapy, requiring pharmacists to stay abreast of new developments. The melphalan-prednisolone and vincristine-doxorubicin-dexamethasone (VAD) regimens, which have been standard treatments for multiple myeloma over the past few decades, have yielded responses without real survival benefits. Transplantation utilizing high-dose chemotherapy has produced the only meaningful survival benefits for patients with multiple myeloma, but many patients are not candidates for this aggressive treatment option. More effective therapies for multiple myeloma are needed.

Objective. To address the mechanisms of action, safety, and efficacy of novel approaches to the treatment of myeloma involving bortezomib, thalidomide and its analogues, lenalidomide and CC-4047 (ActimidTM), and arsenic trioxide as single agents or in combination regimens.

Data sources. Published preclinical and primary clinical trial results, as well as scientific or clinical meeting abstracts. The author determined the relevance and subsequent inclusion of the data.

Conclusions. Bortezomib is approved in the US and Europe as single-agent therapy for the treatment of relapsed or refractory multiple myeloma. Thalidomide, its analogues, and arsenic trioxide have demonstrated activity and are under investigation in this disease. Further clinical trials of the efficacy and toxicity of these novel agents are ongoing and will further define optimal combinations and sequencing with conventional therapies.

Arsenic trioxide poisoning: a description of two acute overdoses

Arsenic is a traditional poison that has a history extending back into ancient times, as a medicinal agent, a homicidal poison and more recently in deliberate and unintentional self-poisoning. We report two cases of acute poisoning with an unwettable formulation of arsenic trioxide. Both patients had early gastrointestinal toxicity and were treated with early whole bowel irrigation (WBI). Chelation therapy with dimercaptosuccinic acid (dimercaptosuccinate, DMSA) was commenced within 24 hours and serial blood and urine arsenic concentrations were measured. Neither patient suffered any adverse outcome in spite of very high blood and urine concentrations of arsenic. Arsenic quantification in blood, urine and faeces suggested that enhanced gastrointestinal decontamination was minimally effective for decontamination and that DMSA for at least two weeks was required.

Update on cardiotoxicity of anti-cancer treatments

BACKGROUND AND AIMS

Anti-cancer treatments markedly improved the prognosis of patients, but unfortunately might be hampered by cardiotoxicity. Both symptomatic and asymptomatic clinical forms of heart failure have been reported, which may be reversible or irreversible. The aim of this review is to provide an overview of the antineoplastic agents associated with cardiac toxicity and of the available diagnostic techniques.

METHODS AND METHODS

This narrative review is based on material from MEDLINE and PUBMED up to November 2015. We looked at the terms antineoplastic drugs and cardiac toxicity in combination with echocardiography, troponins, cardiac magnetic resonance, and positron emission tomography.

RESULTS

Anthracyclines, monoclonal antibodies, fluoropyrimidines, taxanes, alkylating agents, vinka alkaloids were reported to induce different clinical manifestations of cardioxicity. Chest radiotherapy is also associated with various forms of cardiac damage, which are indistinguishable from those found in patients with heart disease of other aetiologies and that may even appear several years after administration. Among diagnostic techniques, echocardiography is a noninvasive, cost-effective, and widely available imaging tool. Nuclear imaging and cardiac magnetic resonance may be used but are not so widely available and are more difficult to perform. Finally, some biomarkers, such as troponins, may be used to evaluate cardiac damage, but establishing the optimal timing of troponin assessment remains unclear and defining the cut-off point for positivity is still an important goal.

CONCLUSIONS

Cardiotoxicity of anti-cancer treatments is associated with development of heart failure. Novel diagnostic tools might be relevant to early recognize irreversible forms cardiac diseases.

Mechanisms of Cardiotoxicity of Cancer Chemotherapeutic Agents: Cardiomyopathy and Beyond

Tremendous strides have been made in the treatment of various oncological diseases such that patients are surviving longer and are having better quality of life. However, the success has been tainted by the iatrogenic cardiac toxicities. This is especially concerning in the younger population who are facing cardiac disease such as heart failure in their 30s and 40s as the consequence of the anthracycline's side effects (used for childhood leukemia and lymphoma). This resulted in the awareness of cardiotoxic effects of anticancer drugs and emergence of a new discipline: oncocardiology. Since then, numerous anticancer drugs have been correlated to cardiomyopathy. Additionally, other cardiovascular effects have been identified, which includes but is not limited to myocardial infarction, thrombosis, hypertension, arrhythmias, and pulmonary hypertension. In this review we examine some of the anticancer agents that mitigate cardiotoxicity and present current knowledge of molecular mechanism(s). The aim of the review is to ignite awareness of emerging cardiotoxic effects as new generations of anticancer agents are being tested in clinical trials and introduced as part of the therapeutic armamentarium to our oncological patients.

Current standard treatment of adult acute promyelocytic leukaemia

The outcome of patients with acute promyelocytic leukaemia (APL) has dramatically improved over the last two decades, due to the introduction of combined all-trans retinoic acid (ATRA) and chemotherapy regimens and, more recently, to the advent of arsenic trioxide (ATO). ATRA and anthracycline-based chemotherapy remains a widely used strategy, providing cure rates above 80%, but it is associated with risk of severe infections and occurrence of secondary leukaemias. ATO is the most effective single agent in APL and, used alone or in combination with ATRA or ATRA and reduced-intensity chemotherapy, results in greater efficacy with considerably less haematological toxicity. The toxic profile of ATO includes frequent, but manageable, QTc prolongation and increase of liver enzymes. Two large randomized studies have shown that ATRA + ATO is superior to ATRA + chemotherapy for newly diagnosed low-risk APL resulting in 2-4 year event-free survival rates above 90% and very few relapses. According to real world data, the spectacular progress in APL outcomes reported in clinical trials has not been paralleled by a significant improvement in early death rates, this remains the most challenging issue for the final cure of the disease.

QT Prolongation and Oncology Drug Development

Many pharmaceutical agents interact with cardiac ion channels resulting in abnormal ventricular repolarization and prolongation of the QT interval. In rare circumstances, this has resulted in the development of the potentially life-threatening arrhythmia, torsades de pointes. It is recognized, however, that accurate measurement of the QT interval is challenging, and it is a poor predictor for the development of this arrhythmia. Nevertheless, QT interval monitoring is an essential part of pharmaceutical development, and significant increases in the QT interval may prevent a drug from gaining approval.

Cardiovascular disease and arsenic exposure in Inner Mongolia, China: a case control study

BACKGROUND

Millions of people are at risk from the adverse effects of arsenic exposure through drinking water. Increasingly, non-cancer effects such as cardiovascular disease have been associated with drinking water arsenic exposures. However, most studies have been conducted in highly exposed populations and lacked individual measurements.

OBJECTIVE

To evaluate the association between cardiovascular disease and well-water arsenic exposure.

METHODS

We conducted a hospital based case control study in Inner Mongolia, China. Cases and controls were prospectively identified and enrolled from a large hospital in the Hangjin Hou area. Cases were patients diagnosed with cardiovascular disease and controls were patients free from cardiovascular disease, admitted for conditions unrelated to arsenic exposure. Water from the primary water source and toenail samples were collected from each subject and tested for inorganic arsenic.

RESULTS

Arsenic exposures were moderate with mean and median arsenic exposures of 8.9 μg/L and 13.1 μg/L, respectively. A total of 298 cases and 275 controls were enrolled. The adjusted odds ratio (AOR) and corresponding 95% confidence interval (95% CI) for a 10 μg/L increase in water arsenic were 1.19 (95% CI: 1.03, 1.38). Compared to exposures less than 10 μg/L, the AOR for water arsenic exposures above 40 μg/L was 4.05 (95% CI: 1.1-14.99, p = 0.04). Nail arsenic above 1.38 μg/g was also associated with an increased risk of cardiovascular disease.

CONCLUSIONS

By using standardized case definitions and collecting individual measurements of arsenic, this study addressed several limitations of previous studies. The results provide further evidence of the association between cardiovascular disease and arsenic at moderate exposures.

Prevalence, management, and clinical consequences of QT interval prolongation during treatment with arsenic trioxide

PURPOSE

Arsenic trioxide (ATO) is a highly effective agent for the treatment of acute promyelocytic leukemia (APL). QT interval prolongation is common with ATO and can pose a barrier to effective administration. The objective of this study was to characterize the prevalence, management, and clinical consequences of QT prolongation in a large cohort of patients treated with ATO.

PATIENTS AND METHODS

We analyzed 3,011 electrocardiograms from 113 patients with non-APL acute myeloid leukemia and myelodysplastic syndrome who were treated on a previously reported clinical trial. QT intervals were assessed using four different correction formulas, and data were correlated with clinical parameters and treatment with ATO.

RESULTS

There were no clinically significant cardiac events in the study population. Of those receiving ATO therapy, 29 patients (26%) had rate-uncorrected QT values above 470 ms and 13 (12%) had values exceeding 500 ms. With the commonly used Bazett rate correction formula, 102 patients (90%) had QTc greater than 470 ms, including 74 (65%) above 500 ms. By using alternative rate correction formulas, only 24% to 32% of patients had rate-corrected QT intervals above 500 ms.

CONCLUSION

QT interval prolongation is common with ATO treatment, but clinically significant arrhythmias are rare and can be avoided with appropriate precautions. Use of the Bazett correction may result in unnecessary interruptions in ATO therapy, and alternative rate correction formulas should be considered for routine electrocardiographic monitoring.

Computer-aided targeting of the PI3K/Akt/mTOR pathway: toxicity reduction and therapeutic opportunities

The PI3K/Akt/mTOR pathway plays an essential role in a wide range of biological functions, including metabolism, macromolecular synthesis, cell growth, proliferation and survival. Its versatility, however, makes it a conspicuous target of many pathogens; and the consequential deregulations of this pathway often lead to complications, such as tumorigenesis, type 2 diabetes and cardiovascular diseases. Molecular targeted therapy, aimed at modulating the deregulated pathway, holds great promise for controlling these diseases, though side effects may be inevitable, given the ubiquity of the pathway in cell functions. Here, we review a variety of factors found to modulate the PI3K/Akt/mTOR pathway, including gene mutations, certain metabolites, inflammatory factors, chemical toxicants, drugs found to rectify the pathway, as well as viruses that hijack the pathway for their own synthetic purposes. Furthermore, this evidence of PI3K/Akt/mTOR pathway alteration and related pathogenesis has inspired the exploration of computer-aided targeting of this pathway to optimize therapeutic strategies. Herein, we discuss several possible options, using computer-aided targeting, to reduce the toxicity of molecularly-targeted therapy, including mathematical modeling, to reveal system-level control mechanisms and to confer a low-dosage combination therapy, the potential of PP2A as a therapeutic target, the formulation of parameters to identify patients who would most benefit from specific targeted therapies and molecular dynamics simulations and docking studies to discover drugs that are isoform specific or mutation selective so as to avoid undesired broad inhibitions. We hope this review will stimulate novel ideas for pharmaceutical discovery and deepen our understanding of curability and toxicity by targeting the PI3K/Akt/mTOR pathway.

Evaluation of early subclinical cardiotoxicity of chemotherapy in breast cancer

Objective:

Cardiac effects of chemotherapy are usually recognized after clinical symptom or sign occurrence in patients with breast cancer. In this study, we aimed to determine the potential subclinical cardiotoxic effects of chemotherapy that were given lower dosage than well known cardiac safety dosage limits in patients with breast cancer during early period.

Methods:

Fifty-one patients consecutively enrolled to this prospective cohort study. All patients were diagnosed as breast cancer at oncology hospital in University of Gaziantep. Before chemotherapy, all of the patients underwent to detailed ECG and echocardiography (ECHO) examinations. After 6 months, detailed ECG and ECHO examinations were repeated and compared with baseline values. Statistical analysis was performed using Shapiro-Wilk tests, Student t-test and Spearman correlation test.

Results:

The average age of patients was 51 and one was male. Statistically significant decrease in ejection fraction was found after treatment (62.3%±3.3 and 59.9%±5.9, p=0.002). Evaluation of diastolic parameters; significant increase in the transmitral A flow velocity and significant decrease of E/A ratio were observed on Doppler ECHO analysis (77.4±19.1 cm/sec versus 86±18 cm/sec, p<0.001; 1.01±0.3 versus 0.9±0.2, p=0.03, respectively). On tissue Doppler analysis we observed that significant reduction in the value of E’ and significantly increase E/E’ ratio were present (12.5±3.6 cm/sec versus 10.7±2.9 cm/sec, p=0.001; 6.6±2.9 versus 7.7±3.3, p=0.04, respectively).

Conclusion:

Chemotherapy has detrimental subclinical effect on both of systolic and diastolic function in early six months period despite the prescription of lower dosage of chemotherapy than well-known cardiac safety dosage limits. Tissue Doppler imaging may be more sensitive than ECG, conventional ECHO and Doppler for determining the subclinical cardiac damage.

Pharmacogenetics of drug-induced arrhythmias

Abnormal functioning of cardiac ion channels can disrupt cardiac myocyte action potentials and thus cause potentially lethal cardiac arrhythmias. Ion channel dysfunction has been observed at all stages in channel ontogeny, from biogenesis to regulation, and arises from genetic or environmental factors, or both. Acquired arrhythmias - including those that are drug induced - are more common than solely inherited arrhythmias but, in some cases, also contain an identifiable genetic component. This interplay between the pharmacology and genetics - known as 'pharmacogenetics' - of cardiac ion channels and the systems that impact them presents both challenges and opportunities to academics, pharmaceutical companies and clinicians seeking to develop and utilize therapies for cardiac rhythm disorders. In this review, we discuss ion channel pharmacogenetics in the context of both causation and treatment of cardiac arrhythmias, focusing on the long QT syndromes.

The Protective Role of Resveratrol against Arsenic Trioxide-Induced Cardiotoxicity

Arsenic trioxide (As₂O₃) shows substantial anticancer activity in patients with acute promyelocytic leukemia (APL). Unfortunately, limiting the application of this effective agent to APL patients is severe cardiotoxicity. Resveratrol, the natural food-derived polyphenolic compound, is well known for its antioxidant properties and protects the cardiovascular system. But the potential role of resveratrol against As₂O₃ in heart via nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) is unclear. The present study evaluated the effects of pretreatment with resveratrol and As₂O₃ on oxidative stress and cardiac dysfunction in rat. In the present study, resveratrol decreased As₂O₃-induced reactive oxygen species generation, oxidative DNA damage, and pathological alterations. In addition, cardiac dysfunction parameters, intracellular calcium and arsenic accumulation, glutathione redox ratio, and cAMP deficiency levels were observed in As₂O₃-treated rats; these changes were attenuated by resveratrol. Furthermore, resveratrol significantly prohibited the downregulation of both Nrf2 and HO-1 gene expressions that were downregulated by As₂O₃, whereas resveratrol did not alter As₂O₃-induced nitric oxide formation. Thus, the protective role of resveratrol against As₂O₃-induced cardiotoxicity is implemented by the maintenance of redox homeostasis (Nrf2-HO-1 pathway) and facilitating arsenic efflux. Our findings suggest coadministration with resveratrol, and As₂O₃ might provide a novel therapeutic strategy for APL.

A phase 1 trial of intravenous 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) in patients with advanced solid tumours

BACKGROUND

4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) is a water-soluble mitochondrial toxin that binds to adenine nucleotide translocase in the inner mitochondrial membrane, thereby targeting cell proliferation. This phase 1 study investigated safety, dose-limiting toxicities (DLTs), maximum tolerated dose (MTD) and pharmacokinetics (PK) of GSAO as a daily 1-h infusion for 5 days a week for 2 weeks in every three. Pharmacodynamics of GSAO was evaluated by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and circulating markers of angiogenesis.

METHODS

Patients with advanced solid tumours received GSAO in a dose-escalation trial according to a standard '3 + 3' design that was guided by toxicity and, for the final dose escalation, by arsenic PK data.

RESULTS

A total of 34 patients were treated with GSAO across 9 dose levels (1.3-44.0 mg/m(2)). Treatment was well tolerated with few adverse events. An additional three patients were enrolled at the 12.4 mg/m(2) dose level following a DLT of derangement of liver function tests (grade 4). At the 44.0 mg/m(2) dose level, two out of three patients had DLTs (reversible encephalopathy; paroxysmal atrial fibrillation).

CONCLUSIONS

The MTD of GSAO was 22.0 mg/m(2)/day. There was no biomarker evidence from DCE-MRI or circulating markers of angiogenesis of an anti-vascular effect of GSAO.

MicroRNA regulation of cardiac conduction and arrhythmias

MicroRNAs are now recognized as important regulators of cardiovascular genes with critical roles in normal development and physiology, as well as disease development. MicroRNAs (miRNAs) are small noncoding RNAs approximately 22 nucleotides in length that regulate expression of target genes through sequence-specific hybridization to the 3' untranslated region of messenger RNAs and either block translation or direct degradation of their target messenger RNA. They have been shown to participate in cardiovascular disease pathogenesis including atherosclerosis, coronary artery disease, myocardial infarction, heart failure, and cardiac arrhythmias. Broadly defined, cardiac arrhythmias are a variation from the normal heart rate or rhythm. Arrhythmias are common and result in significant morbidity and mortality. Ventricular arrhythmias constitute a major cause for cardiac death, particularly sudden cardiac death in the setting of myocardial infarction and heart failure. As advances in pharmacologic, device, and ablative therapy continue to evolve, the molecular insights into the basis of arrhythmia is growing with the ambition of providing additional therapeutic options. Electrical remodeling and structural remodeling are identified mechanisms underlying arrhythmia generation; however, published studies focusing on miRNAs and cardiac conduction are sparse. Recent studies have highlighted the role of miRNAs in cardiac rhythm through regulation of key ion channels, transporters, and cellular proteins in arrhythmogenic conditions. This article aims to review the studies linking miRNAs to cardiac excitability and other processes pertinent to arrhythmia.