Effects of ranolazine on torsades de pointes tachycardias in a healthy isolated rabbit heart model

The Role of Ranolazine in the Treatment of Ventricular Tachycardia and Atrial Fibrillation: A Narrative Review of the Clinical Evidence

Cardiac arrhythmias are among the leading causes of morbidity and mortality worldwide. While antiarrhythmic drugs traditionally represent the first-line management strategy, their use is often limited by profound proarrhythmic effects. Several studies, including randomized control trials (RCTs), have demonstrated the antiarrhythmic efficacy of ranolazine, which is registered as an antianginal agent, while also establishing its safety profile. This review compiles clinical evidence investigating the antiarrhythmic properties of ranolazine, focusing primarily on ventricular tachycardia (VT) and atrial fibrillation (AF), as they are common rhythm abnormalities with serious complications. Data from RCTs indicate that ranolazine reduces VT incidence, although this effect is not universal. Therefore, we attempt to better describe the patient population that gains the most benefit from ranolazine due to VT suppression. Additionally, ranolazine is known to enhance the conversion rate of AF to sinus rhythm when combined with other antiarrhythmic drugs such as amiodarone, highlighting its synergistic effect in the atrium without provoking ventricular dysrhythmias. Despite the heterogeneity in the currently available data, ranolazine appears to be an effective and safe option for the management of various arrhythmias.

Electrocardiographic measures of repolarization heterogeneity are not predictive for Torsades de Pointes among undifferentiated patients with prolonged QTc: A case control study

INTRODUCTION

Torsades de Pointes (TdP) is a potentially lethal polymorphic ventricular tachydysrhythmia associated with and caused by prolonged myocardial repolarization. However, prediction of TdP is challenging. We sought to determine if electrocardiographic myocardial repolarization heterogeneity is necessary and predictive of TdP.

METHODS

We performed a case control study of TdP at a large urban hospital. We identified cases based on a hospital center electrocardiogram (ECG) database search for tracings from 1/2005 to 6/2019 with heart rate corrected QT (QTc) > 500, QRS < 120, and heart rate (HR) < 60, and a subsequent natural language search of electronic health records for the terms: TdP, polymorphic ventricular tachycardia, sudden cardiac death, and relevant variants. Controls were drawn in a 2:1 ratio to cases from a similar pool of ECGs, and matching for QTc, heart rate, sex, and age. We abstracted historical, laboratory, and ECG data using detailed written instructions and an electronic database. We included a second blinded data abstractor to test data abstraction and manual ECG measurement reliability. We used General Electric (GE) QT Guard software for automated repolarization measurements. We compared groups using unpaired statistics.

RESULTS

We included 75 cases and 150 controls. The number of current QTc prolonging medications and serum electrolytes were substantially the same between the two groups. We found no significant difference in measures of QT or T wave repolarization heterogeneity.

CONCLUSION

Electrocardiographic repolarization heterogeneity is not greater in otherwise unselected patients with QTc prolongation who suffer TdP and does not appear predictive of TdP. However, previous observations suggest specific repolarization characteristics may be useful for defined patient subgroups at risk for TdP.

Cross clinical-experimental-computational qualification of in silico drug trials on human cardiac purkinje cells for proarrhythmia risk prediction

The preclinical identification of drug-induced cardiotoxicity and its translation into human risk are still major challenges in pharmaceutical drug discovery. The ICH S7B Guideline and Q&A on Clinical and Nonclinical Evaluation of QT/QTc Interval Prolongation and Proarrhythmic Potential promotes human in silico drug trials as a novel tool for proarrhythmia risk assessment. To facilitate the use of in silico data in regulatory submissions, explanatory control compounds should be tested and documented to demonstrate consistency between predictions and the historic validation data. This study aims to quantify drug-induced electrophysiological effects on in silico cardiac human Purkinje cells, to compare them with existing in vitro rabbit data, and to assess their accuracy for clinical pro-arrhythmic risk predictions. The effects of 14 reference compounds were quantified in simulations with a population of in silico human cardiac Purkinje models. For each drug dose, five electrophysiological biomarkers were quantified at three pacing frequencies, and results compared with available in vitro experiments and clinical proarrhythmia reports. Three key results were obtained: 1) In silico, repolarization abnormalities in human Purkinje simulations predicted drug-induced arrhythmia for all risky compounds, showing higher predicted accuracy than rabbit experiments; 2) Drug-induced electrophysiological changes observed in human-based simulations showed a high degree of consistency with in vitro rabbit recordings at all pacing frequencies, and depolarization velocity and action potential duration were the most consistent biomarkers; 3) discrepancies observed for dofetilide, sotalol and terfenadine are mainly caused by species differences between humans and rabbit. Taken together, this study demonstrates higher accuracy of in silico methods compared to in vitro animal models for pro-arrhythmic risk prediction, as well as a high degree of consistency with in vitro experiments commonly used in safety pharmacology, supporting the potential for industrial and regulatory adoption of in silico trials for proarrhythmia prediction.

Ranolazine: An Old Drug with Emerging Potential; Lessons from Pre-Clinical and Clinical Investigations for Possible Repositioning

Ischemic heart disease is a significant public health problem with high mortality and morbidity. Extensive scientific investigations from basic sciences to clinics revealed multilevel alterations from metabolic imbalance, altered electrophysiology, and defective Ca²⁺/Na⁺ homeostasis leading to lethal arrhythmias. Despite the recent identification of numerous molecular targets with potential therapeutic interest, a pragmatic observation on the current pharmacological R&D output confirms the lack of new therapeutic offers to patients. By contrast, from recent trials, molecules initially developed for other fields of application have shown cardiovascular benefits, as illustrated with some anti-diabetic agents, regardless of the presence or absence of diabetes, emphasizing the clear advantage of “old” drug repositioning. Ranolazine is approved as an antianginal agent and has a favorable overall safety profile. This drug, developed initially as a metabolic modulator, was also identified as an inhibitor of the cardiac late Na⁺ current, although it also blocks other ionic currents, including the hERG/Ikr K⁺ current. The latter actions have been involved in this drug’s antiarrhythmic effects, both on supraventricular and ventricular arrhythmias (VA). However, despite initial enthusiasm and promising development in the cardiovascular field, ranolazine is only authorized as a second-line treatment in patients with chronic angina pectoris, notwithstanding its antiarrhythmic properties. A plausible reason for this is the apparent difficulty in linking the clinical benefits to the multiple molecular actions of this drug. Here, we review ranolazine’s experimental and clinical knowledge on cardiac metabolism and arrhythmias. We also highlight advances in understanding novel effects on neurons, the vascular system, skeletal muscles, blood sugar control, and cancer, which may open the way to reposition this “old” drug alone or in combination with other medications.

Dynamic features of cardiac vector as alternative markers of drug-induced spatial dispersion

INTRODUCTION

The abnormal amplification of ventricular repolarization dispersion (VRD) has long been linked to proarrhythmia risk. Recently, the measure of VRD through electrocardiogram intervals has been strongly questioned. The search for an efficient and non-invasive surrogate marker of drug-induced dispersion effects constitute an urgent research challenge.

METHODS

Herein, drug-induced ventricular dispersion is generated by d-Sotalol supply in an In-vitro rabbit heart model. A cilindrical chamber simulates the thorax and a multi-electrode net is used to obtain spatial electrocardiographic signals. Cardiac vector dynamics is captured by novel velocity cardiomarkers obtained by quaternion methods. Through statistical analysis and machine learning technics, we compute potential dispersion markers that could define proarrhythmic risk.

RESULTS

The cardiomarkers with the greatest statistical significance, both obtained from the electrical cardiac vector, were: the QT_ω, which is the difference between first and last maxima of angular velocity and λ21_v^T, the roundness of linear velocity. When comparing with the performance of the current standards (89%), this pair was able to correctly separate 21 out of 22 experiments achieving a performance of 95%. Moreover, the QT_ω computes in a much more robust basis the QT interval, the current index for drug regulation.

DISCUSSION

These velocity markers circumvent the problems of accuratelly finding the fiducial points such as the always tricky T-wave end. Given the high performance they achieved, it is provided a promising outcome for future applications to the detection of anomalous changes of heterogeneity that may be useful for the purposes of torsadogenic toxicity studies.

Selective late sodium current inhibitor GS-458967 suppresses Torsades de Pointes by mostly affecting perpetuation but not initiation of the arrhythmia

Background and Purpose

Enhanced late sodium current (late I_Na) in heart failure and long QT syndrome type 3 is proarrhythmic. This study investigated the antiarrhythmic effect and mode of action of the selective and potent late I_Na inhibitor GS‐458967 (GS967) against Torsades de Pointes arrhythmias (TdP) in the chronic atrioventricular block (CAVB) dog.

Experimental Approach

Electrophysiological and antiarrhythmic effects of GS967 were evaluated in isolated canine ventricular cardiomyocytes and CAVB dogs with dofetilide‐induced early afterdepolarizations (EADs) and TdP, respectively. Mapping of intramural cardiac electrical activity in vivo was conducted to study effects of GS967 on spatial dispersion of repolarization.

Key Results

GS967 (IC₅₀~200nM) significantly shortened repolarization in canine ventricular cardiomyocytes and sinus rhythm (SR) dogs, in a concentration and dose‐dependent manner. In vitro, despite addition of 1μM GS967, dofetilide‐induced EADs remained present in 42% and 35% of cardiomyocytes from SR and CAVB dogs, respectively. Nonetheless, GS967 (787±265nM) completely abolished dofetilide‐induced TdP in CAVB dogs (10/14 after dofetilide to 0/14 dogs after GS967), while single ectopic beats (sEB) persisted in 9 animals. In vivo mapping experiments showed that GS967 significantly reduced spatial dispersion of repolarization: cubic dispersion was significantly decreased from 237±54ms after dofetilide to 123±34ms after GS967.

Conclusion and Implications

GS967 terminated all dofetilide‐induced TdP without completely suppressing EADs and sEB in vitro and in vivo, respectively. The antiarrhythmic mode of action of GS967, through the reduction of spatial dispersion of repolarization, seems to predominantly impede the perpetuation of arrhythmic events into TdP rather than their initiating trigger.

Impact of ranolazine on ventricular arrhythmias - A systematic review

Ranolazine is a new medication for the treatment of refractory angina. However, except its anti-anginal properties, it has been found to act as an anti-arrhythmic. The aim of our systematic review is to present the existing data about the impact of ranolazine in ventricular arrhythmias. We searched MEDLINE and Cochrane databases as well clinicaltrials.gov until September 1, 2017 to find all studies (clinical trials, observational studies, case reports/series) reported data about the impact of ranolazine in ventricular arrhythmias. Our search revealed 14 studies (3 clinical trials, 2 observational studies, 8 case reports, 1 case series). These data reported a beneficial impact of ranolazine in ventricular tachycardia/fibrillation, premature ventricular beats, and ICD interventions in different clinical settings. The existing data highlight the anti-arrhythmic properties of ranolazine in ventricular arrhythmias.

The Significance of the Late Na+ Current for Arrhythmia Induction and the Therapeutic Antiarrhythmic Potential of Ranolazine

The purpose of this article is to review the basis of arrhythmogenesis, the functional and clinical role of the late Na current, and its therapeutic inhibition. Under pathological conditions such as ischemia and heart failure this current is abnormally enhanced and influences cellular electrophysiology as a proarrhythmic substrate in myocardial pathology. Ranolazine the only approved late Na current blocker has been demonstrated to produce antiarrhythmic effects in the atria and the ventricle. We summarize recent experimental and clinical studies of ranolazine and other experimental late Na current blockers and discuss the significance of the available data.

Ranolazine antagonizes catecholamine-induced dysfunction in isolated cardiomyocytes, but lacks long-term therapeutic effects in vivo in a mouse model of hypertrophic cardiomyopathy

AIMS

Hypertrophic cardiomyopathy (HCM) is often accompanied by increased myofilament Ca(2+) sensitivity and diastolic dysfunction. Recent findings indicate increased late Na(+) current density in human HCM cardiomyocytes. Since ranolazine has the potential to decrease myofilament Ca(2+) sensitivity and late Na(+) current, we investigated its effects in an Mybpc3-targeted knock-in (KI) mouse model of HCM.

METHODS AND RESULTS

Unloaded sarcomere shortening and Ca(2+) transients were measured in KI and wild-type (WT) cardiomyocytes. Measurements were performed at baseline (1 Hz) and under increased workload (30 nM isoprenaline (ISO), 5 Hz) in the absence or presence of 10 µM ranolazine. KI myocytes showed shorter diastolic sarcomere length at baseline, stronger inotropic response to ISO, and drastic drop of diastolic sarcomere length under increased workload. Ranolazine attenuated ISO responses in WT and KI cells and prevented workload-induced diastolic failure in KI. Late Na(+) current density was diminished and insensitive to ranolazine in KI cardiomyocytes. Ca(2+) sensitivity of skinned KI trabeculae was slightly decreased by ranolazine. Phosphorylation analysis of cAMP-dependent protein kinase A-target proteins and ISO concentration-response measurements on muscle strips indicated antagonism at β-adrenoceptors with 10 µM ranolazine shifting the ISO response by 0.6 log units. Six-month treatment with ranolazine (plasma level >20 µM) demonstrated a β-blocking effect, but did not reverse cardiac hypertrophy or dysfunction in KI mice.

CONCLUSION

Ranolazine improved tolerance to high workload in mouse HCM cardiomyocytes, not by blocking late Na(+) current, but by antagonizing β-adrenergic stimulation and slightly desensitizing myofilaments to Ca(2+). This effect did not translate in therapeutic efficacy in vivo.