Sex-Related Differences in Ventricular Tachyarrhythmia Events in Patients With Implantable Cardioverter-Defibrillator and Prior Ventricular Tachyarrhythmias

BACKGROUND

Data on the risk of ventricular tachycardia (VT), ventricular fibrillation (VF), and death by sex in patients with prior VT/VF are limited.

OBJECTIVES

This study aimed to assess sex-related differences in implantable cardioverter-defibrillator (ICD)-treated VT/VF events and death in patients implanted for secondary prevention or primary prevention ICD indications who experienced VT/VF before enrollment in the RAID (Ranolazine Implantable Cardioverter-Defibrillator) trial.

METHODS

Sex-related differences in the first and recurrent VT/VF requiring antitachycardia pacing or ICD shock and death were evaluated in 714 patients.

RESULTS

There were 124 women (17%) and 590 men observed during a mean follow-up of 26.81 ± 14.52 months. Compared to men, women were at a significantly lower risk of VT/VF/death (HR: 0.67; P = 0.029), VT/VF (HR: 0.68; P = 0.049), VT/VF treated with antitachycardia pacing (HR: 0.59; P = 0.019), and VT/VF treated with ICD shock (HR: 0.54; P = 0.035). The risk of recurrent VT/VF was also significantly lower in women (HR: 0.35; P < 0.001). HR for death was similar to the other endpoints (HR: 0.61; P = 0.162). In comparison to men, women presented with faster VT rates (196 ± 32 beats/min vs 177 ± 30 beats/min, respectively; P = 0.002), and faster shock-requiring VT/VF rates (258 ± 56 beats/min vs 227 ± 57 beats/min, respectively; P = 0.30). There was a significant interaction for the risk of VT/VF by race (P = 0.013) with White women having significantly lower risk than White men (HR: 0.36; P < 0.001), whereas Black women had a similar risk to Black men (HR: 1.06; P = 0.851).

CONCLUSIONS

Women with a history of prior VT/VF experienced a lower risk recurrent VT/VF requiring ICD therapy when compared to men. Black Women had a risk similar to men, whereas the lower risk for VT/VF in women was observed primarily in White women. (Ranolazine Implantable Cardioverter-Defibrillator Trial; NCT01215253).

Novel predictive approaches for drug-induced convulsions in non-human primates using machine learning and heart rate variability analysis

Drug-induced convulsions are a major challenge to drug development because of the lack of reliable biomarkers. Using machine learning, our previous research indicated the potential use of an index derived from heart rate variability (HRV) analysis in non-human primates as a biomarker for convulsions induced by GABAA receptor antagonists. The present study aimed to explore the application of this methodology to other convulsants and evaluate its specificity by testing non-convulsants that affect the autonomic nervous system. Telemetry-implanted males were administered various convulsants (4-aminopyridine, bupropion, kainic acid, and ranolazine) at different doses. Electrocardiogram data gathered during the pre-dose period were employed as training data, and the convulsive potential was evaluated using HRV and multivariate statistical process control. Our findings show that the Q-statistic-derived convulsive index for 4-aminopyridine increased at doses lower than that of the convulsive dose. Increases were also observed for kainic acid and ranolazine at convulsive doses, whereas bupropion did not change the index up to the highest dose (1/3 of the convulsive dose). When the same analysis was applied to non-convulsants (atropine, atenolol, and clonidine), an increase in the index was noted. Thus, the index elevation appeared to correlate with or even predict alterations in autonomic nerve activity indices, implying that this method might be regarded as a sensitive index to fluctuations within the autonomic nervous system. Despite potential false positives, this methodology offers valuable insights into predicting drug-induced convulsions when the pharmacological profile is used to carefully choose a compound.

Efficacy and Safety of a Metabolic Modulator Drug in Chronic Stable Angina: Review of Evidence from Clinical Trials

A number of newer antianginal agents, including nicorandil, trimetazidine, and ivabradine, have been synthesized in recent years, but ranolazine, a piperazine derivative that partially inhibits fatty acid oxidation and the late INa current in animal models, is of particular interest mechanistically. Earlier clinical trials with immediate-release ranolazine led to the current sustained-release version tested in the Monotherapy Assessment of Ranolazine In Stable Angina (MARISA) (n = 193) and Combination Assessment of Ranolazine In Stable Angina (CARISA) trials (n = 823) of patients with chronic angina and severe limitation of exercise capacity (ie, < 5 metabolic equivalents). MARISA was a placebo-controlled, randomized trial that compared ranolazine monotherapy (500 mg, 1000 mg, and 1500 mg, twice daily) to placebo. CARISA was a placebo-controlled trial that randomized patients on background 1-blocker or calcium antagonist therapy to placebo or ranolazine (750 mg or 1000 mg, twice daily). Both studies showed a significant increase in total exercise duration, time to angina onset, and time to 1 mm ST segment depression. The average magnitude of increase in exercise duration over placebo was 29 to 56 seconds at peak and 24 to 46 seconds at trough with the 3 doses tested in MARISA, and 24 to 34 seconds greater than placebo with the 2 doses used in CARISA. The beneficial effect was achieved without clinically important changes in rest or exercise heart rate or blood pressure. Weekly angina attack frequency and nitroglycerin usage were significantly reduced in a dose-dependent manner in the 12-week CARISA trial. Reported adverse effects were similar in MARISA and CARISA and consisted of asthenia, nausea, constipation, and dizziness. Syncope, reported in 8 patients at doses of 1000 mg twice daily or more may be related to attenuation of α-1 receptor activity. The mean QTc interval increased with dose and was less than 10 msec on ranolazine at 1000 mg twice daily. The mortality rates at 1 and 2 years in MARISA and CARISA open-label run-on studies were 2% and less than 5%, acceptable for this high-risk population with limited exercise capacity. In conclusion, clinical trial evidence with ranolazine to date is consistent with its proposed mechanism of action and demonstrates an effective antianginal profile that may benefit patients with severe chronic angina.

Serotonin and urocortin 1 in the dorsal raphe and Edinger-Westphal nuclei after early life stress in serotonin transporter knockout rats

The interaction of early life stress (ELS) and the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) has been associated with increased risk to develop depression in later life. We have used the maternal separation paradigm as a model for ELS exposure in homozygous and heterozygous 5-HTT knockout rats and measured urocortin 1 (Ucn1) mRNA and/or protein levels, Ucn1 DNA methylation, as well as 5-HT innervation in the centrally projecting Edinger-Westphal (EWcp) and dorsal raphe (DR) nuclei, both implicated in the regulation of stress response. We found that ELS and 5-HTT genotype increased the number of 5-HT neurons in specific DR subdivisions, and that 5-HTT knockout rats showed decreased 5-HT innervation of EWcp-Ucn1 neurons. Furthermore, ELS was associated with increased DNA methylation of the promoter region of the Ucn1 gene and increased expression of 5-HT receptor 1A in the EWcp. In contrast, 5-HTT deficiency was associated with site-specific alterations in DNA methylation of the Ucn1 promoter, and heterozygous 5-HTT knockout rats showed decreased expression of CRF receptor 1 in the EWcp. Together, our findings extend the existing literature on the relationship between EWcp-Ucn1 and DR-5-HT neurons. These observations will further our understanding on their potential contribution to mediate affect as a function of ELS interacting with 5-HTTLPR.

Metabolic Modulators for Chronic Cardiac Ischemia

Many patients with ischemic heart disease continue to experience anginal symptoms despite revascularization and treatment with antianginal medications. The effectiveness of current anti-ischemic medications is limited by their hemodynamic side effects, such as hypotension and bradycardia, which result in compromised organ perfusion. In this article, we review five novel agents (ranolazine, trimetazidine, L-carnitine, ribose, and dichloroacetate) under investigation for treatment of ischemic heart disease that work by enhancing the efficiency of the myocardium, rather than decreasing its work. This new paradigm promises to eliminate these side effects.

Ranolazine, an Inhibitor of the Late Sodium Channel Current, Reduces Postischemic Myocardial Dysfunction in the Rabbit

Ranolazine is a selective inhibitor of the late sodium current relative to peak sodium channel current, and via this mechanism, it may decrease sodium-dependent intracellular calcium overload during ischemia and reperfusion. Ranolazine reduces the frequency of angina attacks, but there is little information on its effects on myocardial stunning after short-term ischemia. The objective of this study was to test the effects of ranolazine on left ventricular (LV) function and myocardial stunning after ischemia/reperfusion in rabbits. Myocardial stunning was induced in rabbits by 15 minutes of coronary artery occlusion (CAO) followed by 3 hours reperfusion. Ten minutes before CAO, rabbits were randomly assigned to vehicle (n = 15) or ranolazine (2 mg/kg bolus plus 60 μg/kg/min infusion, IV, n = 15). Myocardial stunning was assessed by LV 2-dimensional echocardiography using, as a marker of severity, ischemic free-wall fractional thickening (FWft; systolic wall thickness – diastolic wall thickness/diastolic wall thickness). Regional ejection fraction (EF) was also assessed. During CAO, FWft was depressed in both groups, indicating an ischemic insult (FWft was reduced from 0.62 ± 0.05 at baseline to 0.10 ± 0.04 in vehicle and from 0.73 ± 0.05 to 0.26 ± 0.07 in ranolazine, P < 0.05, ranolazine vs vehicle). After reperfusion, previously ischemic myocardium remained stunned; however, FWft recovered significantly better in ranolazine (0.51 ± 0.05) than in vehicle (0.35 ± 0.04, P = .027). Baseline EF was 0.65 ± 0.02 in the ranolazine and 0.68 ± 0.02 in vehicle ( P = ns). During CAO, EF was reduced by 36% ± 6% in vehicle versus only 20% ± 6% in ranolazine ( P < .05). At the end of reperfusion, EF remained depressed in both groups, but the reduction in the vehicle group (25% ± 5%) was significantly worse than in ranolazine (9% ± 4%, P = .017). Improvement in function was independent of necrosis (negligible) or differences in hemodynamics (no differences between groups). Ranolazine treatment reduced myocardial stunning following brief ischemia/reperfusion suggesting that inhibiting the late sodium channel current may be a novel approach to treating stunning independent of effects on hemodynamics.

Ranolazine protects from doxorubicin-induced oxidative stress and cardiac dysfunction

AIMS

Doxorubicin is widely used against cancer; however, it can produce heart failure (HF). Among other hallmarks, oxidative stress is a major contributor to HF pathophysiology. The late INa inhibitor ranolazine has proven effective in treating experimental HF. Since elevated [Na+]i is present in failing myocytes, and has been recently linked with reactive oxygen species (ROS) production, our aim was to assess whether ranolazine prevents doxorubicin-induced cardiotoxicity, and whether blunted oxidative stress is a mechanism accounting for such protection.

METHODS AND RESULT

In C57BL6 mice, doxorubicin treatment for 7 days produced LV dilation and decreased echo-measured fractional shortening (FS). Ranolazine (305 mg/kg/day) prevented LV dilation and dysfunction when co-administered with doxorubicin. Doxorubicin-induced cardiotoxicity was accompanied instead by elevations in atrial natriuretic peptide (ANP), BNP, connective tissue growth factor (CTGF), and matrix metalloproteinase 2 (MMP2) mRNAs, which were not elevated on co-treatment with ranolazine. Alterations in extracellular matrix remodelling were confirmed by an increase in interstitial collagen, which did not rise in ranolazine-co-treated hearts. Levels of poly(ADP-ribose) polymerase (PARP) and pro-caspase-3 measured by western blotting were lowered with doxorubicin, with increased cleavage of caspase-3, indicating activation of the proapoptotic machinery. Again, ranolazine prevented this activation. Furthermore, in HL-1 cardiomyocytes transfected with HyPer to monitor H2O2 emission, besides reducing the extent of cell death, ranolazine prevented the occurrence of oxidative stress caused by doxorubicin. Interestingly, similar protective results were obtained with the Na+/Ca2+ exchanger (NCX) inhibitor KB-R7943.

CONCLUSIONS

Ranolazine protects against experimental doxorubicin cardiotoxicity. Such protection is accompanied by a reduction in oxidative stress, suggesting that INa modulates cardiac redox balance, resulting in functional and morphological derangements.

Cost-utility of ranolazine for the symptomatic treatment of patients with chronic angina pectoris in Spain

BACKGROUND

Ranolazine is an antianginal agent that was approved in the EU in 2008 as an add-on therapy for symptomatic chronic angina pectoris treatment in patients who are inadequately controlled by, or are intolerant to, first-line antianginal therapies. These patients' quality of life is significantly affected by more frequent angina events, which increase the risk of revascularization.

OBJECTIVE

To assess the cost-utility of ranolazine versus placebo as an add-on therapy for the symptomatic treatment of patients with chronic angina pectoris in Spain.

METHODS

A decision tree model with 1-year time horizon was designed. Transition probabilities and utility values for different angina frequencies were obtained from the literature. Costs were obtained from Spanish official DRGs for patients with chronic angina pectoris. We calculated the incremental cost-utility ratio of using ranolazine compared with a placebo. Sensitivity analyses, by means of Monte Carlo simulations, were performed. Acceptability curves and expected value of perfect information were calculated.

RESULTS

The incremental cost-utility ratio was €8,455 per quality-adjusted life-year (QALY) per patient in Spain. Sensitivity analyses showed that if the decision makers' willingness to pay is €15,000 per QALY, the treatment with ranolazine will be cost effective at a 95 % level of confidence. The incremental cost-utility ratio is particularly sensitive to changes in utility values of those non-hospitalized patients with mild or moderate angina frequency.

CONCLUSIONS

Ranolazine is a highly efficient add-on therapy for the symptomatic treatment of chronic angina pectoris in patients who are inadequately controlled by, or intolerant to, first-line antianginal therapies in Spain.

Myopathy during treatment with the antianginal drug ranolazine

Ranolazine is a medication indicated for treatment of chronic angina and is a partial inhibitor of the fatty acid β-oxidation. We present an adult patient who developed subacute progressive muscle weakness and exercise-induced myalgia, soon after increasing the daily dose of ranolazine, in the setting of therapy with simvastatin. CK persisted normal throughout the duration of the weakness and muscle biopsy showed a lipid storage myopathy for which no underlying genetic defect was identified. Discontinuation of both drugs resulted in clinical improvement. Although simvastatin may have contributed to the myopathy, the temporal relation between the increase in ranolazine dose and the onset of the weakness would favor ranolazine as major culprit for the weakness.

Blockade of Na+ channels in pancreatic α-cells has antidiabetic effects

Pancreatic α-cells express voltage-gated Na(+) channels (NaChs), which support the generation of electrical activity leading to an increase in intracellular calcium, and cause exocytosis of glucagon. Ranolazine, a NaCh blocker, is approved for treatment of angina. In addition to its antianginal effects, ranolazine has been shown to reduce HbA1c levels in patients with type 2 diabetes mellitus and coronary artery disease; however, the mechanism behind its antidiabetic effect has been unclear. We tested the hypothesis that ranolazine exerts its antidiabetic effects by inhibiting glucagon release via blockade of NaChs in the pancreatic α-cells. Our data show that ranolazine, via blockade of NaChs in pancreatic α-cells, inhibits their electrical activity and reduces glucagon release. We found that glucagon release in human pancreatic islets is mediated by the Nav1.3 isoform. In animal models of diabetes, ranolazine and a more selective NaCh blocker (GS-458967) lowered postprandial and basal glucagon levels, which were associated with a reduction in hyperglycemia, confirming that glucose-lowering effects of ranolazine are due to the blockade of NaChs. This mechanism of action is unique in that no other approved antidiabetic drugs act via this mechanism, and raises the prospect that selective Nav1.3 blockers may constitute a novel approach for the treatment of diabetes.

Ranolazine refractory angina registry: 1-year results

Patients with refractory angina (RA) have limited therapeutic options and significant limitations in their quality of life. Ranolazine is approved for patients with chronic stable angina but has not been studied in patients with RA. The Ranolazine Refractory Angina Registry was designed to evaluate the safety, tolerability, and effectiveness in RA patients. In a dedicated RA clinic using an extensive prospective database, 100 patients were enrolled. Angina class, medications, major adverse cardiac events including death, myocardial infarction, and revascularization were obtained at 1, 6, and 12 months. Overall 43% of patients had a ≥2 class improvement in angina. At 1 year, 57% patients remained on ranolazine (91.2%; 500 mg BID), including 58% with a ≥2 class improvement in angina. Reasons for discontinuation included: side effects (n = 16), major adverse cardiac events (n = 10), cost (n = 5), ineffective (n = 6), cost and ineffective (n = 3), and unknown (n = 3). In conclusion, ranolazine is an effective antianginal therapy in patients with RA; still at 1 year only 57% of patients remained on ranolazine because of side effects, suboptimal effectiveness, cost, or progression of disease.

Antiepileptic activity of preferential inhibitors of persistent sodium current

OBJECTIVE

Evidence from basic neurophysiology and molecular genetics has implicated persistent sodium current conducted by voltage-gated sodium (NaV ) channels as a contributor to the pathogenesis of epilepsy. Many antiepileptic drugs target NaV channels and modulate neuronal excitability, mainly by a use-dependent block of transient sodium current, although suppression of persistent current may also contribute to the efficacy of these drugs. We hypothesized that a drug or compound capable of preferential inhibition of persistent sodium current would have antiepileptic activity.

METHODS

We examined the antiepileptic activity of two selective persistent sodium current blockers ranolazine, a U.S. Food and Drug Administration (FDA)-approved drug for treatment of angina pectoris, and GS967, a novel compound with more potent effects on persistent current, in the epileptic Scn2a(Q54) mouse model. We also examined the effect of GS967 in the maximal electroshock model and evaluated effects of the compound on neuronal excitability, propensity for hilar neuron loss, development of mossy fiber sprouting, and survival of Scn2a(Q54) mice.

RESULTS

We found that ranolazine was capable of reducing seizure frequency by approximately 50% in Scn2a(Q54) mice. The more potent persistent current blocker GS967 reduced seizure frequency by >90% in Scn2a(Q54) mice and protected against induced seizures in the maximal electroshock model. GS967 greatly attenuated abnormal spontaneous action potential firing in pyramidal neurons acutely isolated from Scn2a(Q54) mice. In addition to seizure suppression in vivo, GS967 treatment greatly improved the survival of Scn2a(Q54) mice, prevented hilar neuron loss, and suppressed the development of hippocampal mossy fiber sprouting.

SIGNIFICANCE

Our findings indicate that the selective persistent sodium current blocker GS967 has potent antiepileptic activity and that this compound could inform development of new agents.

Relation of T-wave alternans to mortality and nonsustained ventricular tachycardia in patients with non-ST-segment elevation acute coronary syndrome from the MERLIN-TIMI 36 trial of ranolazine versus placebo

We explored the utility of T-wave alternans (TWA) in predicting mortality in patients with non-ST-segment elevation acute coronary syndrome (NSTEACS). Maximum TWA was calculated using Modified Moving Average method from continuous electrocardiographic recordings in patients with left ventricular ejection fraction <40% and ventricular tachycardia (VT) ≥4 beats during index hospitalization or sudden cardiac death during the follow-up year and age- and sex-matched controls in the Metabolic Efficiency with Ranolazine for Less Ischemia in Non-ST Elevation Acute Coronary Syndrome-Thrombolysis In Myocardial Infarction (MERLIN-TIMI) 36 trial. All patients received standard therapy for NSTEACS plus ranolazine (n = 109) or placebo (n = 101). Median follow-up was 1 year. Baseline clinical characteristics did not differ between patients with elevated TWA (≥47 μV) compared with lower levels. Patients with TWA ≥47 μV at admission had increased risk of total mortality (adjusted odds ratio [ORadj] 2.35, p = 0.04) during follow-up and VT ≥4 beats (ORadj 2.70, p = 0.01) during hospitalization with a trend toward increased cardiovascular death risk (ORadj 2.18, p = 0.07) during follow-up. In patients receiving placebo, TWA ≥47 μV on day 6 was associated with increased risk of total mortality (OR 4.12, 95% confidence interval 1.25 to 13.64, p = 0.02) and cardiovascular death (OR 4.73, p = 0.01) during follow-up. No deaths occurred among patients with TWA ≥47 μV assigned to ranolazine. In conclusion, in patients with NSTEACS and left ventricular ejection fraction <40%, TWA ≥47 μV early after admission is associated with increased risk of mortality at 1 year and with nonsustained VT during hospitalization. TWA may be useful in risk estimation in patients with NSTEACS. The possibility that TWA may serve as a therapeutic target deserves further exploration.

Update on ranolazine in the management of angina

Mortality rates attributable to coronary heart disease have declined in recent years, possibly related to changes in clinical presentation patterns and use of proven secondary prevention strategies. Chronic stable angina (CSA) remains prevalent, and the goal of treatment is control of symptoms and reduction in cardiovascular events. Ranolazine is a selective inhibitor of the late sodium current in myocytes with anti-ischemic and metabolic properties. It was approved by the US Food and Drug Administration in 2006 for use in patients with CSA. Multiple, randomized, placebo-controlled trials have shown that ranolazine improves functional capacity and decreases anginal episodes in CSA patients, despite a lack of a significant hemodynamic effect. Ranolazine did not improve cardiovascular mortality or affect incidence of myocardial infarction in the MERLIN (Metabolic Efficiency with Ranolazine for Less Ischemia in Non-ST-Elevation Acute Coronary Syndrome)-TIMI (Thrombolysis In Myocardial Infarction) 36 trial, but significantly decreased the incidence of recurrent angina. More recently, ranolazine has been shown to have beneficial and potent antiarrhythmic effects, both on supraventricular and ventricular tachyarrhythmias, largely due to its inhibition of the late sodium current. Randomized controlled trials testing these effects are underway. Lastly, ranolazine appears to be cost-effective due to its ability to decrease angina-related hospitalizations and improve quality of life.

Use of ranolazine in patients with stable angina pectoris

The current American Heart Association/American College of Cardiology guidelines for patients with stable angina pectoris recommend β-blockers as the initial drug therapy for prevention of angina pectoris (class I B indication). Long-acting nitrates or calcium channel blockers should be prescribed for prevention of angina when β-blockers are contraindicated or not tolerated secondary to side effects (class I B indication). Long-acting nitrates or calcium channel blockers in combination with β-blockers should be prescribed for angina prevention when initial treatment with β-blockers is unsuccessful (class I B indication). Only sublingual nitroglycerin or nitroglycerin spray should be used for immediate relief of angina pectoris (class I B indication). Ranolazine with β-blockers can be used for prevention of angina when initial treatment with β-blockers is not successful (class IIa A indication). If angina persists despite treatment with β-blockers, long-acting nitrates and calcium channel blockers, we recommend the addition of ranolazine for prevention of stable angina pectoris. This editorial discusses the contemporary role of ranolazine in the management of patients with stable angina pectoris.

Slow junctional rhythm, QTc prolongation and transient torsades de-pointes following combined use of Ivabradine, Diltiazem and Ranolazine

A case of unstable angina developed slow junctional rhythm with QTc prolongation and transient Torsades de pointes following simultaneous use of Ivabradine, Diltiazem and Ranolazine. Effect of Diltiazem on hepatic isoenzyme CYP 3A could be responsible. Such a combination should be avoided.

[New developments in the antiarrhythmic therapy of atrial fibrillation]

Atrial fibrillation often affects elderly people with cardiovascular disease and takes a progressive course with increasing resistance to treatment. For the latter, electrical and structural changes (remodelling) seem to be responsible that are directly related to the high excitatory rate in the atria. Therapeutic strategies for atrial fibrillation consist of (i) treating the underlying cardiovascular disease, (ii) re-establishing sinus rhythm and (iii) reducing ventricular rate. Rapid pharmacological or electrical cardioversion is expected to prevent remodelling. Classical antiarrhythmic drugs are notoriously ineffective and burdened with serious cardiac and extracardiac side effects so that there is an urgent need for effective and safe novel compounds. In this review the three recently introduced drugs dronedarone, vernakalant and ranolazine are discussed with respect to the use in atrial fibrillation. Other new antiarrhythmic agents are still in the developmental phase and aim at atria-selective mechanisms thereby excluding ventricular proarrhythmic effects. The mechanisms of action will be discussed in the context of the present understanding of the pathophysiology of onset and maintenance of atrial fibrillation.

Ranolazine: new approach for the treatment of stable angina pectoris

Myocardial ischemia is a metabolic problem involving reduced delivery of oxygen to cardiac mitochondria, resulting in less ATP formation, acceleration of glycolysis and production of lactate and H+ by the cell. Traditional therapies for ischemia aim at restoring the balance between mitochondrial ATP production and breakdown by reducing the need for ATP via suppression of heart rate, blood pressure and cardiac contractility, or by increasing oxygen delivery via increased myocardial blood flow. Despite optimal treatment with traditional hemodynamically oriented drugs (beta-adrenergic receptor antagonist, Ca2+ channel antagonist and nitrates), many patients continue to suffer from angina. Thus, there is a need for anti-anginal drugs that act directly on cardiomyocytes to lessen the metabolic abnormalities induced by ischemia and reduce the symptoms (chest pain and exercise intolerance). Ranolazine has been demonstrated to improve exercise time to angina or 1 mm of ST-segment depression in a manner similar to currently approved drugs, but without any significant effects on heart rate or blood pressure at rest or during exercise. In two Phase III trials, ranolazine improved exercise tolerance and reduced the frequency of angina attacks in chronic severe angina patients when administered either as monotherapy or on a background of atenolol, amlodinine or diltiazem. At present, ranolazine is under review for US Food and Drug Administration approval and, if approved, it will represent the first drug of its class in the USA.

Refractory atrial fibrillation effectively treated with ranolazine

Atrial fibrillation is the most common sustained cardiac arrhythmia which is often troublesome to manage. Currently, rhythm and rate control medications are the mainstays of therapy. In 2 amiodarone-refractory highly symptomatic patients, an innovative approach using ranolazine, which selectively acts on Na+ channels and delays atrial depolarization, was tried successfully.

Ranolazine for congenital and acquired late INa-linked arrhythmias: in silico pharmacological screening

RATIONALE

The antianginal ranolazine blocks the human ether-a-go-go-related gene-based current IKr at therapeutic concentrations and causes QT interval prolongation. Thus, ranolazine is contraindicated for patients with preexisting long-QT and those with repolarization abnormalities. However, with its preferential targeting of late INa (INaL), patients with disease resulting from increased INaL from inherited defects (eg, long-QT syndrome type 3 or disease-induced electric remodeling (eg, ischemic heart failure) might be exactly the ones to benefit most from the presumed antiarrhythmic properties of ranolazine.

OBJECTIVE

We developed a computational model to predict if therapeutic effects of pharmacological targeting of INaL by ranolazine prevailed over the off-target block of IKr in the setting of inherited long-QT syndrome type 3 and heart failure.

METHODS AND RESULTS

We developed computational models describing the kinetics and the interaction of ranolazine with cardiac Na(+) channels in the setting of normal physiology, long-QT syndrome type 3-linked ΔKPQ mutation, and heart failure. We then simulated clinically relevant concentrations of ranolazine and predicted the combined effects of Na(+) channel and IKr blockade by both the parent compound ranolazine and its active metabolites, which have shown potent blocking effects in the therapeutically relevant range. Our simulations suggest that ranolazine is effective at normalizing arrhythmia triggers in bradycardia-dependent arrhythmias in long-QT syndrome type 3 as well tachyarrhythmogenic triggers arising from heart failure-induced remodeling.

CONCLUSIONS

Our model predictions suggest that acute targeting of INaL with ranolazine may be an effective therapeutic strategy in diverse arrhythmia-provoking situations that arise from a common pathway of increased pathological INaL.

Role of late sodium current as a potential arrhythmogenic mechanism in the progression of pressure-induced heart disease

The aim of the study was to determine the characteristics of the late Na current (INaL) and its arrhythmogenic potential in the progression of pressure-induced heart disease. Transverse aortic constriction (TAC) was used to induce pressure overload in mice. After one week the hearts developed isolated hypertrophy with preserved systolic contractility. In patch-clamp experiments both, INaL and the action potential duration (APD90) were unchanged. In contrast, after five weeks animals developed heart failure with prolonged APDs and slowed INaL decay time which could be normalized by addition of the INaL inhibitor ranolazine (Ran) or by the Ca/calmodulin-dependent protein kinase II (CaMKII) inhibitor AIP. Accordingly the APD90 could be significantly abbreviated by Ran, tetrodotoxin and the CaMKII inhibitor AIP. Isoproterenol increased the number of delayed afterdepolarizations (DAD) in myocytes from failing but not sham hearts. Application of either Ran or AIP prevented the occurrence of DADs. Moreover, the incidence of triggered activity was significantly increased in TAC myocytes and was largely prevented by Ran and AIP. Western blot analyses indicate that increased CaMKII activity and a hyperphosphorylation of the Nav1.5 at the CaMKII phosphorylation site (Ser571) paralleled our functional observations five weeks after TAC surgery. In pressure overload-induced heart failure a CaMKII-dependent augmentation of INaL plays a crucial role in the AP prolongation and generation of cellular arrhythmogenic triggers, which cannot be found in early and still compensated hypertrophy. Inhibition of INaL and CaMKII exerts potent antiarrhythmic effects and might therefore be of potential therapeutic interest. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".

Ranolazine-induced myopathy in a patient on chronic statin therapy

We present a case demonstrating clinical, electrophysiological, serological, and radiological evidence of a myopathy induced by ranolazine, in a patient otherwise asymptomatic on chronic statin therapy. The patient developed proximal weakness, serum creatine kinase levels of 1875 U/L, electromyography with muscle membrane instability and small short-duration motor unit potentials, and magnetic resonance imaging evidence of muscle edema. The manifestations began within one week of initiation of ranolazine and improved within days after discontinuation. Ranolazine is a weak inhibitor of CYP3A4 known to increase the serum level of simvastatin and its active metabolite 2-fold. We postulate that the addition of ranolazine to a medical regimen that included atorvastatin induced a myoncecrotic myopathy.

Mechanisms of ranolazine's dual protection against atrial and ventricular fibrillation

Coronary artery disease and heart failure carry concurrent risk for atrial fibrillation and life-threatening ventricular arrhythmias. We review evidence indicating that at therapeutic concentrations, ranolazine has potential for dual suppression of these arrhythmias. Mechanisms and clinical implications are discussed.

Ranolazine: clinical applications and therapeutic basis

Ranolazine is currently approved for use in chronic angina. The basis for this use is likely related to inhibition of late sodium channels with resultant beneficial downstream effects. Randomized clinical trials have demonstrated an improvement in exercise capacity and reduction in angina episodes with ranolazine. This therapeutic benefit occurs without the hemodynamic effects seen with the conventional antianginal agents. The inhibition of late sodium channels as well as other ion currents has a central role in the potential use of ranolazine in ischemic heart disease, arrhythmias, and heart failure. Despite its QTc-prolonging action, albeit minimal, clinical data have not shown a predisposition to torsades de pointes, and the medication has shown a reasonable safety profile even in those with structural heart disease. In this article we present the experimental and clinical data that support its current therapeutic role, and provide insight into potential future clinical applications.

Tolerability and pharmacokinetics of ranolazine following single and multiple sustained-release doses in Chinese healthy adult volunteers: a randomized, open-label, Latin square design, phase I study

BACKGROUND AND OBJECTIVES

Ranolazine was approved by the US Food and Drug Administration in January 2006 for the treatment of chronic angina pectoris, and is the first approved agent from a new class of anti-anginal drugs in almost 25 years. The primary objective of this study was to determine the concentration of ranolazine in human plasma using the liquid chromatography/tandem mass spectrometry (LC-MS/MS) method and to compare the pharmacokinetic properties of ranolazine after administration of single and multiple doses of ranolazine in healthy Chinese adult volunteers.

METHODS

A randomized, open-label, single- and multiple-dose study design was used in the study. Subjects were randomized to receive a single dose of 500, 1,000, or 1,500 mg of ranolazine. Those who received the single dose continued on to the multiple-dose phase and received 500 mg twice daily for 7 days. In the single-dose phase, blood samples were collected from 0 to 48 h after drug administration. In the multiple-dose phase, samples were obtained before drug administration at 8:00 am and 8:00 pm on days 6 and 7 to determine the minimum steady-state plasma concentration (C(min,ss)) of ranolazine; on day 8, samples were collected from 0 to 48 h after drug administration. All values were expressed as means (standard deviations [SDs]). Adverse events (AEs) were monitored throughout the study via subject interview, vital signs, and blood sampling.

RESULTS

The LC-MS/MS method was developed and validated. Twelve Chinese subjects (six men, six women) were enrolled in the single-dose phase of the pharmacokinetic study. The mean (SD) age of the subjects was 24.7 (1.6) years; their mean (SD) weight was 61.3 (6.4) kg, their mean (SD) height was 165.7 (4.5) cm, and their mean (SD) body mass index was 21.6 (6.6) kg/m(2). The main pharmacokinetic parameters [mean (SD)] for ranolazine after administration of a single oral dose of 500, 1,000, and 1,500 mg were as follows: maximum plasma concentration (C(max)) 741.5 (253.0), 1,355.0 (502.0), and 2,328.7 (890.5) ng/mL, respectively; area under the concentration-time curve from time zero to 48 h (AUC(48)) 9,071.9 (3,400.0), 16,573.5 (6,806.2), and 29,324.5 (10,857.2) ng·h/mL; AUC from time zero extrapolated to infinity (AUC(∞)) 9,826.7 (3,152.0), 16,882.4 (6,790.8), and 29,923.5 (10,706.3) ng·h/mL; time to reach C(max) (t(max)) 5.3 (1.4), 4.2 (1.2), and 5.9 (2.8) h; elimination half-life (t(½)) 6.4 (3.3), 6.4 (3.5), and 6.7 (4.3) h. Mean (SD) values for the main pharmacokinetic parameters for ranolazine after administration of multiple doses were as follows: steady-state C(max) (C(max,ss)) 1,732.9 (547.3) ng/mL; C(min,ss) 838.1 (429.8) ng/mL; steady-state AUC at time t (AUC(ss,(t))) 14,655.5 (5,624.2) ng·h/mL; average steady-state plasma drug concentration during multiple-dose administration (C(av,ss)) 1,221.3 (468.7) ng/mL; t(max) 3.46 (1.48) h; t(½) 6.28 (2.48) h.

CONCLUSION

In this group of healthy Chinese subjects, AUC and C(max) increased proportionally with the dose, whereas t(½) was independent of the dose. The pharmacokinetic properties of ranolazine were linear after administration of single oral doses of 500 to 1,500 mg. Compared with the pharmacokinetic parameters of the subjects who received a single dose, those who received multiple doses (twice daily) of ranolazine had a larger AUC from time zero to the time of the last measurable concentration (AUC(last)), AUC(∞), C(max), and apparent total body clearance of drug from plasma after oral administration (CL/F), and shorter t(max) (all p < 0.05). Furthermore, some of the main pharmacokinetic parameters of ranolazine may reflect ethnic differences. This dosage was generally well tolerated by all the subjects.

Role of ranolazine in the management of stable angina

Ischemic heart disease (IHD) is a major cause of death in Western Countries and accounts for very high costs worldwide. In this review we discussed the pathogenesis, symptoms, diagnosis, prognosis and management of chronic IHD. In particular, we discussed about the percutaneous coronary interventions and coronary artery bypass grafting, as well as to clinical trials that evaluated the advantages of one approach versus another. Pharmacological treatment is among major objectives of the review and for each class of therapeutic agents an evaluation of well-conducted clinical trials is provided. The most important drug classes in IHD treatment are betablockers, calcium channel blockers, nitrates, antiplatelet agents, and ACE-inhibitors. In addition to these agents, also new treatment options are evaluated in patients with stable IHD. Ranolazine, in particular, is a innovative anti-anginal drug with a great successful in the management of patients with refractory angina. A pharmacological as well as clinical profile of this drug is provided.

Effect of ranolazine on arterial endothelial function in patients with type 2 diabetes mellitus

OBJECTIVE

To assess the effect of ranolazine on systemic vascular function in patients with type II diabetes mellitus (T2DM).

METHODS

We randomized 30 consecutive T2DM patients with no evidence of cardiovascular disease and no insulin therapy to receive one of the following 3 forms of treatment in a blinded fashion: ranolazine, 375 mg bid for 3 weeks (group 1); ranolazine, 375 mg bid for 2 weeks, followed by placebo bid for 1 week (group 2); placebo bid for 3 weeks (group 3). Flow-mediated dilation (FMD) and nitrate-mediated dilation (NMD) of the right brachial artery were assessed at baseline and after 48 h, and 2 and 3 weeks.

RESULTS

FMD and NMD were similar among groups at baseline. Compared to the basal value, FMD significantly improved after 2 weeks in group 1 and in group 2 (p < 0.01 for both), but not in group 3. At 3 weeks, FMD remained improved, compared to baseline, in group 1 (p < 0.05), whereas returned to basal values in group 2 (p = 0.89 vs. baseline). No changes in NMD were observed in any group.

CONCLUSIONS

In this controlled study, ranolazine was able to improve endothelial function in T2DM patients.

Carbon monoxide induces cardiac arrhythmia via induction of the late Na+ current

RATIONALE

Clinical reports describe life-threatening cardiac arrhythmias after environmental exposure to carbon monoxide (CO) or accidental CO poisoning. Numerous case studies describe disruption of repolarization and prolongation of the QT interval, yet the mechanisms underlying CO-induced arrhythmias are unknown.

OBJECTIVES

To understand the cellular basis of CO-induced arrhythmias and to identify an effective therapeutic approach.

METHODS

Patch-clamp electrophysiology and confocal Ca(2+) and nitric oxide (NO) imaging in isolated ventricular myocytes was performed together with protein S-nitrosylation to investigate the effects of CO at the cellular and molecular levels, whereas telemetry was used to investigate effects of CO on electrocardiogram recordings in vivo.

MEASUREMENTS AND MAIN RESULTS

CO increased the sustained (late) component of the inward Na(+) current, resulting in prolongation of the action potential and the associated intracellular Ca(2+) transient. In more than 50% of myocytes these changes progressed to early after-depolarization-like arrhythmias. CO elevated NO levels in myocytes and caused S-nitrosylation of the Na(+) channel, Na(v)1.5. All proarrhythmic effects of CO were abolished by the NO synthase inhibitor l-NAME, and reversed by ranolazine, an inhibitor of the late Na(+) current. Ranolazine also corrected QT variability and arrhythmias induced by CO in vivo, as monitored by telemetry.

CONCLUSIONS

Our data indicate that the proarrhythmic effects of CO arise from activation of NO synthase, leading to NO-mediated nitrosylation of Na(V)1.5 and to induction of the late Na(+) current. We also show that the antianginal drug ranolazine can abolish CO-induced early after-depolarizations, highlighting a novel approach to the treatment of CO-induced arrhythmias.

Comparison of effectiveness of ranolazine plus amiodarone versus amiodarone alone for conversion of recent-onset atrial fibrillation

Ranolazine, an antianginal agent with antiarrhythmic properties, prevents atrial fibrillation (AF) in patients with acute coronary syndrome. In experimental models, the combination of ranolazine and amiodarone has marked synergistic effects that potently suppress AF. Currently, the clinical effect of the ranolazine-amiodarone combination for the conversion of AF is unknown. This prospective randomized pilot study compared the safety and efficacy of ranolazine plus amiodarone versus amiodarone alone for the conversion of recent-onset AF. We enrolled 51 consecutive patients with AF (<48-hour duration) eligible for pharmacologic cardioversion. Patients (33 men, 63 ± 8 years of age) were randomized to intravenous amiodarone for 24 hours (group A, n = 26) or to intravenous amiodarone plus oral ranolazine 1,500 mg at time of randomization (group A + R, n = 25). The 2 groups were well balanced with respect to clinical characteristics and left atrial diameter. Conversion within 24 hours (primary end point) was achieved in 22 patients (88%) in group A + R versus 17 patients (65%) in group A (p = 0.056). Time to conversion was shorter in group A + R than in group A (9.8 ± 4.1 vs 14.6 ± 5.3 hours, p = 0.002). According to Cox regression analysis, left atrial diameter and A + R treatment were the only independent predictors of time to conversion (hazard ratio 5.35, 95% confidence interval 2.37 to 12.11, p <0.001; hazard ratio 0.81, 95% confidence interval 0.74 to 0.88, p <0.001, respectively). There were no proarrhythmic events in either group. In conclusion, addition of ranolazine to standard amiodarone therapy is equally safe and appears to be more effective compared to amiodarone alone for conversion of recent-onset AF.

New treatment options for late Na current, arrhythmias, and diastolic dysfunction

The late Na current is of pathophysiological importance for the heart. Ranolazine is an innovative anti-ischemic and antianginal agent that inhibits the late Na current, thereby reducing the Na-dependent Ca-overload, which improves diastolic tone and oxygen handling during myocardial ischemia. In addition, ranolazine seems to exert beneficial effects on diastolic cardiac function. Moreover, there are experimental and clinical data about its antiarrhythmic properties. A beneficial atrial selectivity of ranolazine has been suggested that may be helpful for the treatment of atrial fibrillation. The purpose of this review article is to discuss possible future clinical indications based on novel experimental and preclinical results and the significance of the available data.

[Involvement of veratridine-induced increase of reverse Na(+)/Ca(2+) exchange current in intracellular Ca(2+) overload and extension of action potential duration in rabbit ventricular myocytes]

The objectives of this study were to investigate the effects of veratridine (VER) on persistent sodium current (I(Na.P)), Na(+)/Ca(2+) exchange current (I(NCX)), calcium transients and the action potential (AP) in rabbit ventricular myocytes, and to explore the mechanism in intracellular calcium overload and myocardial contraction enhancement by using whole-cell patch clamp recording technique, visual motion edge detection system, intracellular calcium measurement system and multi-channel physiological signal acquisition and processing system. The results showed that I(Na.P) and reverse I(NCX) in ventricular myocytes were obviously increased after giving 10, 20 μmol/L VER, with the current density of I(Na.P) increasing from (-0.22 ± 0.12) to (-0.61 ± 0.13) and (-2.15 ± 0.14) pA/pF (P < 0.01, n = 10) at -20 mV, and that of reverse I(NCX) increasing from (1.62 ± 0.12) to (2.19 ± 0.09) and (2.58 ± 0.11) pA/pF (P < 0.05, n = 10) at +50 mV. After adding 4 μmol/L tetrodotoxin (TTX), current density of I(Na.P) and reverse I(NCX) returned to (-0.07 ± 0.14) and (1.69 ± 0.15) pA/pF (P < 0.05, n = 10). Another specific blocker of I(Na.P), ranolazine (RAN), could obviously inhibit VER-increased I(Na.P) and reverse I(NCX). After giving 2.5 μmol/L VER, the maximal contraction rate of ventricular myocytes increased from (-0.91 ± 0.29) to (-1.53 ± 0.29) μm/s (P < 0.01, n = 7), the amplitude of contraction increased from (0.10 ± 0.04) to (0.16 ± 0.04) μm (P < 0.05, n = 7), and the baseline of calcium transients (diastolic calcium concentration) increased from (1.21 ± 0.08) to (1.37 ± 0.12) (P < 0.05, n = 7). After adding 2 μmol/L TTX, the maximal contraction rate and amplitude of ventricular myocytes decreased to (-0.86 ± 0.24) μm/s and (0.09 ± 0.03) μm (P < 0.01, n = 7) respectively. And the baseline of calcium transients reduced to (1.17 ± 0.09) (P < 0.05, n = 7). VER (20 μmol/L) could extend action potential duration at 50% repolarization (APD(50)) and at 90% repolarization (APD(90)) in ventricular myocytes from (123.18 ± 23.70) to (271.90 ± 32.81) and from (146.94 ± 24.15) to (429.79 ± 32.04) ms (P < 0.01, n = 6) respectively. Early afterdepolarizations (EADs) appeared in 3 out of the 6 cases. After adding 4 μmol/L TTX, APD(50) and APD(90) were reduced to (99.07 ± 22.81) and (163.84 ± 26.06) ms (P < 0.01, n = 6) respectively, and EADs disappeared accordingly in 3 cases. It could be suggested that: (1) As a specific agonist of the I(Na.P), VER could result in I(Na.P) increase and intracellular Na(+) overload, and subsequently intracellular Ca(2+) overload with the increase of reverse I(NCX). (2) The VER-increased I(Na.P) could further extend the action potential duration (APD) and induce EADs. (3) TTX could restrain the abnormal VER-induced changes of the above-mentioned indexes, indicating that these abnormal changes were caused by the increase of I(Na.P). Based on this study, it is concluded that as the I(Na.P) agonist, VER can enhance reverse I(NCX) by increasing I(Na.P), leading to intracellular Ca(2+) overload and APD abnormal extension.

Ranolazine for the treatment of refractory angina in a veterans population

BACKGROUND

Pivotal ranolazine trials did not require optimization of conventional medical therapy including coronary revascularization and antianginal drug therapy prior to ranolazine use. This case series describes the use of ranolazine for the treatment of chronic stable angina refractory to maximal medical treatment in a veterans population.

RESULTS

A total of 18 patients with a median age of 66 years were identified. All patients had prior percutaneous coronary intervention and/or coronary artery bypass graft surgery; 83% had three-vessel coronary artery disease, with left main disease present in 39% of patients. Prior to initiating ranolazine, antianginal use consisted of beta blockers (94%), long-acting nitrates (83%) and calcium channel blockers (61%). Median blood pressure (116.2/61.8 mmHg) and pulse (65 beats per min) were controlled. Median preranolazine angina episodes and sublingual nitroglycerin (SLNTG) doses per week were 14 and 10, respectively, with a Canadian Cardiovascular Society (CCS) angina grade of III-IV in 67% of patients. After initiation of ranolazine, median angina episodes per week and SLNTG doses used per week decreased to 0.7 and 0, respectively, with CCS grade of III-IV declining to 17%. Of the 18 subjects enrolled, 44% had complete resolution of angina episodes.

CONCLUSION

The addition of ranolazine to maximally tolerated conventional antianginal drug therapy post coronary revascularization was associated with decreases in angina episodes and SLNTG utilization and improvement in CCS angina grades. Ranolazine may provide an effective treatment option for revascularized patients with refractory angina.

[Analysis of primary metabolites of ranolazine in dog urine by LC-MS(n)]

Ranolazine and metabolites in dog urine were identified by LC-MS(n). Dog urine samples were collected after ig 30 mg x kg(-1) ranolazine, then the samples were enriched and purified through solid-phase extraction cartridge. The purified samples were analyzed by LC-MS(n). The possible metabolites were discovered by comparing the full scan and SIM chromatograms of the test samples with the corresponding blanks. Seventeen phase I metabolites and fourteen phase II metabolites were identified in dog urine. Three metabolites were identified by comparing with the control article. The metabolites were formed via the following metabolic pathways: O-demethylation, O-dearylation, hydroxylation, N-dealkylation, amide hydrolysis, glucuronidation and sulfation. The LC-MS(n) method is suitable for the rapid identification of drug and its metabolites in biologic samples.

Pharmacology of myocardial calcium-handling

Disturbed myocardial calcium (Ca(+)) handling is one of the pathophysiologic hallmarks of cardiovascular diseases such as congestive heart failure, cardiac hypertrophy, and certain types of tachyarrhythmias. Pharmacologic treatment of these diseases thus focuses on restoring myocardial Ca(2+) homeostasis by interacting with Ca(2+)-dependent signaling pathways. In this article, we review the currently used pharmacologic agents that are able to restore or maintain myocardial Ca(2+) homeostasis and their mechanism of action as well as emerging new substances.

A focus on antiarrhythmic properties of ranolazine

Ranolazine is an antianginal drug that inhibits a number of ion currents that are important for the genesis of transmembrane cardiac action potential. It was initially developed as an antianginal agent but was found to additionally exert antiarrhythmic actions, due to its multichannel-blocking properties. In recent years, several studies about the antiarrhythmic properties of ranolazine were conducted, demonstrating the beneficial effects of this drug in both atrial and ventricular arrhythmias, such as atrial fibrillation, ventricular premature beats, ventricular tachycardia, torsades de pointes, and ventricular fibrillation. Our aim is to briefly review the main points of these studies, most more experimental than clinical.

Comparison of electrophysiological and antiarrhythmic effects of vernakalant, ranolazine, and sotalol in canine pulmonary vein sleeve preparations

BACKGROUND

Vernakalant (VER) is a relatively atrial-selective antiarrhythmic drug capable of blocking potassium and sodium currents in a frequency- and voltage-dependent manner. Ranolazine (RAN) is a sodium-channel blocker shown to exert antiarrhythmic effects in pulmonary vein (PV) sleeves. dl-Sotalol (SOT) is a β-blocker commonly used in the rhythm-control treatment of atrial fibrillation. This study evaluated the electrophysiological and antiarrhythmic effects of VER, RAN, and SOT in canine PV sleeve preparations in a blinded fashion.

METHODS

Transmembrane action potentials were recorded from canine superfused PV sleeve preparations exposed to VER (n = 6), RAN (n = 6), and SOT (n = 6). Delayed afterdepolarizations were induced in the presence of isoproterenol and high-calcium concentrations by periods of rapid pacing.

RESULTS

In PV sleeves, VER, RAN, and SOT (3-30 μM) produced small (10-15 ms) increases in action potential duration. The effective refractory period, diastolic threshold of excitation, and the shortest S(1)-S(1) cycle length permitting 1:1 activation were significantly increased by VER and RAN in a rate- and concentration-dependent manner. VER and RAN significantly reduced V(max) in a concentration- and rate-dependent manner. SOT did not significantly affect the effective refractory period, V(max), diastolic threshold of excitation, or the shortest S(1)-S(1) cycle length permitting 1:1 activation. All 3 agents (3-30 μM) suppressed delayed afterdepolarization-mediated triggered activity induced by isoproterenol and high calcium.

CONCLUSIONS

In canine PV sleeves, the effects of VER and RAN were similar and largely characterized by concentration- and rate-dependent depression of sodium-channel-mediated parameters, which were largely unaffected by SOT. All 3 agents demonstrated an ability to effectively suppress delayed afterdepolarization-induced triggers of atrial arrhythmia.

[Ranolazine in the treatment of chronic stable angina]

Coronary artery disease is the leading cause of death in Europe and in the US and angina is the most common symptom associated with stable coronary artery disease. Despite receiving optimal antianginal therapy, based on agents such as beta-blockers, calcium channel antagonists and nitrates, many patients continue to experience angina. Furthermore, the administration of these drugs is limited by adverse effects such as bradycardia or hypotension. Ranolazine is a new antianginal agent, recently approved as add-on therapy in patients with stable angina. This review will focus on its mechanism of action, tolerability, highlighting the clinical benefit coming from its use.