Ranolazine: new paradigm for management of myocardial ischemia, myocardial dysfunction, and arrhythmias

Fatty Acid Metabolism in Endothelial Cell

The endothelium is a monolayer of cells lining the inner blood vessels. Endothelial cells (ECs) play indispensable roles in angiogenesis, homeostasis, and immune response under normal physiological conditions, and their dysfunction is closely associated with pathologies such as cardiovascular diseases. Abnormal EC metabolism, especially dysfunctional fatty acid (FA) metabolism, contributes to the development of many diseases including pulmonary hypertension (PH). In this review, we focus on discussing the latest advances in FA metabolism in ECs under normal and pathological conditions with an emphasis on PH. We also highlight areas of research that warrant further investigation.

Recent Advances in the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease in which stenosis or obstruction of the pulmonary arteries (PAs) causes an increase in PA pressure, leading to right-sided heart failure and death. Basic research has revealed a decrease in the levels of endogenous vasodilators, such as prostacyclin, and an increase in the levels of endogenous vasoconstrictors, such as endothelin, in patients with PAH, leading to the development of therapeutic agents. Currently, therapeutic agents for PAH target three pathways that are selective for PAs: the prostacyclin, endothelin, and nitric oxide pathways. These treatments improve the prognosis of PAH patients. In this review, we introduce new drug therapies and provide an overview of the current therapeutic agents.

Beyond hypertension: Diastolic dysfunction associated with cancer treatment in the era of cardio-oncology

Cancer patients are at an increased risk of cardiovascular events. Both old-generation cytostatics/cytotoxics and new-generation "targeted" drugs can in fact damage cardiomyocytes, endothelial cells of veins and arteries, specialized cells of the conduction system, pericardium, and valves. A new discipline, cardio-oncology, has therefore developed with the aim of protecting cancer patients from cardiovascular events, while also providing them with the best possible oncologic treatment. Anthracyclines have long been known to elicit cardiotoxicity that, depending on treatment- or patient-related factors, may progress with a variable velocity toward cardiomyopathy and systolic heart failure. However, early compromise of diastolic function may precede systolic dysfunction, and a progression of early diastolic dysfunction to diastolic rather than systolic heart failure has been documented in long-term cancer survivors. This chapter first describes general notions about hypertension in the cancer patient and then moves on reviewing the pathophysiology and clinical trajectories of diastolic dysfunction, and the molecular mechanisms of anthracycline-induced diastolic dysfunction. Diastolic dysfunction can in fact be caused and/or aggravated by hypertension. Pharmacologic foundations and therapeutic opportunities to prevent or treat diastolic dysfunction before it progresses toward heart failure are also reviewed, with a special emphasis on the mechanisms of action of drugs that raised hopes to treat diastolic dysfunction in the general population (sacubitril/valsartan, guanylyl cyclase activators, phosphodiesterase inhibitors, ranolazine, inhibitors of type-2 sodium-glucose-inked transporter). Cardio-oncologists will be confronted with the risk:benefit ratio of using these drugs in the cancer patient.

Pharmacology of Ranolazine versus Common Cardiovascular Drugs in Patients with Early Diastolic Dysfunction Induced by Anthracyclines or Nonanthracycline Chemotherapeutics: A Phase 2b Minitrial

We have reported that anthracyclines and nonanthracycline chemotherapeutics caused diastolic dysfunction in cancer patients without cardiovascular risk factors. Diastolic dysfunction occurred as early as 1 week after the last chemotherapy cycle and manifested as impaired myocardial relaxation at echocardiography or persistent elevations of B-type natriuretic peptide (BNP) or troponin. The antianginal drug ranolazine shows cardiac relaxant effects that we considered of value to treat early diastolic dysfunction induced by cancer drugs; therefore, 24 low-risk patients with post-chemotherapy diastolic dysfunction were randomized (1:1) to ranolazine or the investigator's choice of common cardiovascular drugs, such as β-blockers and/or angiotensin-converting enzyme inhibitors or loop diuretics (best standard therapy, BST). After 5 weeks, 12 of 12 patients on ranolazine recovered from diastolic dysfunction, whereas 3 of 12 patients on BST did not improve; however, adverse events (not serious) were apparently more frequent for ranolazine than for BST (4/12 vs. 1/12). Ranolazine did not lower blood pressure, whereas BST reduced systolic pressure and caused a trend toward a reduced diastolic pressure. Most patients at randomization showed tachycardia resulting from chemotherapy-related anemia. Hemoglobin recovery contributed to normalizing heart rate in these patients; however, some patients in the ranolazine arm developed tachycardia through chronotropic effects of high BNP levels and returned to a normal heart rate through the effects of ranolazine on decreasing BNP levels. This minitrial describes the potential effects of ranolazine on relieving chemotherapy-related diastolic dysfunction; however, clinical implications of these findings need to be characterized by studies with an adequate sample size. SIGNIFICANCE STATEMENT: The antianginal drug ranolazine causes cardiac relaxant effects that might relieve diastolic dysfunction. In a clinical pharmacology study, 24 patients were randomized (1:1) to receive ranolazine or common cardiovascular drugs to treat early diastolic dysfunction induced by anthracycline-based or nonanthracycline chemotherapy. Ranolazine relieved diastolic dysfunction in these patients. The safety profile of ranolazine in cancer patients is similar to that of the general population. Compared with common cardiovascular drugs, ranolazine relieved diastolic dysfunction without lowering blood pressure. The sample size of this study was nonetheless too small to permit considerations about the potential clinical value of ranolazine for oncologic patients with early diastolic dysfunction induced by anthracyclines or nonanthracycline chemotherapeutics. This information should be obtained by studies with an adequate sample size.

The Endogenous Lusitropic and Chronotropic Agent, B-Type Natriuretic Peptide, Limits Cardiac Troponin Release in Cancer Patients with an Early Impairment of Myocardial Relaxation Induced by Anthracyclines

We have reported that cancer patients treated with anthracycline-based or nonanthracycline chemotherapy developed an early impairment of myocardial relaxation at echocardiography or persistent elevations of the cardiac hormone B-type natriuretic peptide (BNP). Post-hoc pharmacologic analyses showed that BNP elevations were induced by impaired relaxation and caused positive lusitropic effects that maintained normal relaxation. High BNP levels and impaired relaxation were therefore characterized as mutually exclusive manifestations of diastolic dysfunction, but high BNP levels resulted in positive chronotropism and inappropriate tachycardia. Some patients developed increased circulating levels of cardiac troponin I isoform (cTnI), a marker of cardiomyocyte necrosis. Here we have characterized whether cTnI elevations correlated with diastolic dysfunction that manifested as impaired relaxation or a high level of BNP. The effects of high BNP levels on cTnI elevations were also characterized. We show that impaired relaxation or high BNP levels were significantly more frequent in patients with cTnI elevations. High BNP levels diminished the plasma peak and area under the curve of cTnI, but this result was accompanied by inappropriate tachycardia. cTnI elevations occurred only in patients treated with anthracyclines; moreover, the association of impaired relaxation or high BNP levels with cTnI elevations was significantly more frequent in doxorubicin-treated patients compared with patients treated with its analog, epirubicin. These findings describe cause-and-effect relations between impaired relaxation and cardiomyocyte necrosis, illuminate the role of anthracycline analogs, denote that the beneficial effects of BNP in relieving impaired relaxation and cardiomyocyte necrosis are counterbalanced by inappropriate tachycardia. Patients showing troponin elevations and impaired relaxation or high BNP levels should be treated with lusitropic drugs that lack a positive chronotropism.

Sarcoendoplasmic reticulum Ca(2+) ATPase. A critical target in chlorine inhalation-induced cardiotoxicity

Autopsy specimens from human victims or experimental animals that die due to acute chlorine gas exposure present features of cardiovascular pathology. We demonstrate acute chlorine inhalation-induced reduction in heart rate and oxygen saturation in rats. Chlorine inhalation elevated chlorine reactants, such as chlorotyrosine and chloramine, in blood plasma. Using heart tissue and primary cardiomyocytes, we demonstrated that acute high-concentration chlorine exposure in vivo (500 ppm for 30 min) caused decreased total ATP content and loss of sarcoendoplasmic reticulum calcium ATPase (SERCA) activity. Loss of SERCA activity was attributed to chlorination of tyrosine residues and oxidation of an important cysteine residue, cysteine-674, in SERCA, as demonstrated by immunoblots and mass spectrometry. Using cardiomyocytes, we found that chlorine-induced cell death and damage to SERCA could be decreased by thiocyanate, an important biological antioxidant, and by genetic SERCA2 overexpression. We also investigated a U.S. Food and Drug Administration-approved drug, ranolazine, used in treatment of cardiac diseases, and previously shown to stabilize SERCA in animal models of ischemia-reperfusion. Pretreatment with ranolazine or istaroxime, another SERCA activator, prevented chlorine-induced cardiomyocyte death. Further investigation of responsible mechanisms showed that ranolazine- and istaroxime-treated cells preserved mitochondrial membrane potential and ATP after chlorine exposure. Thus, these studies demonstrate a novel critical target for chlorine in the heart and identify potentially useful therapies to mitigate toxicity of acute chlorine exposure.

Effects of ranolazine on exercise capacity, right ventricular indices, and hemodynamic characteristics in pulmonary arterial hypertension: a pilot study

Ranolazine, a late inward sodium current and fatty acid oxidation inhibitor, may improve right ventricular (RV) function in pulmonary arterial hypertension (PAH); however, the safety and efficacy of ranolazine in humans with PAH is unknown. Therefore, we sought to (1) determine whether ranolazine is safe and well tolerated in PAH and (2) explore ranolazine's effect on symptoms, exercise capacity, RV structure and function, and hemodynamic characteristics. We therefore conducted a 3-month, prospective, open-label pilot study involving patients with symptomatic PAH (n = 11) and echocardiographic evidence of RV dysfunction. We evaluated the safety and tolerability of ranolazine and compared symptoms, exercise capacity, exercise bicycle echocardiographic parameters, and invasive hemodynamic parameters between baseline and 3 months of ranolazine therapy using paired t tests. Of the 11 patients enrolled, one discontinued ranolazine therapy due to a drug-drug interaction after 3 days of therapy. All 10 of the remaining patients continued therapy for 3 months, and 8 (80%) of 10 completed all study tests. After 3 months, ranolazine administration was safe and associated with improvement in functional class (P = 0.0013), reduction in RV size (P = 0.015), improved RV function (improvement in RV strain during exercise at 3 months; P = 0.037), and a trend toward improved exercise time and exercise watts on bicycle echocardiography (P = 0.06 and 0.01, respectively). Ranolazine was not associated with improvement in invasive hemodynamic parameters. In conclusion, in a pilot study involving PAH, ranolazine therapy was safe and well tolerated, and it resulted in improvement in symptoms and echocardiographic parameters of RV structure and function but did not alter invasive hemodynamic parameters. ClinicalTrials.gov Identifier: NCT01174173.

The concomitant management of cancer therapy and cardiac therapy

Antitumor drugs have long been known to introduce a measurable risk of cardiovascular events. Cardio-Oncology is the discipline that builds on collaboration between cardiologists and oncologists and aims at screening, preventing or minimizing such a risk. Overt concern about "possible" cardiovascular toxicity might expose cancer patients to the risk of tumor undertreatment and poor oncologic outcome. Careful analysis of risk:benefit balance is therefore central to the management of patients exposed to potentially cardiotoxic drugs. Concomitant or sequential management of cardiac and cancer therapies should also be tailored to the following strengths and weaknesses: i) molecular mechanisms and clinical correlates of cardiotoxicity have been characterized to some extent for anthracyclines but not for other chemotherapeutics or new generation "targeted" drugs, ii) anthracyclines and targeted drugs cause different mechanisms of cardiotoxicity (type I versus type II), and this classification should guide strategies of primary or secondary prevention, iii) with anthracyclines and nonanthracycline chemotherapeutics, cardiovascular events may occur on treatment as well as years or decades after completing chemotherapy, iv) some patients may be predisposed to a higher risk of cardiac events but there is a lack of prospective studies that characterized optimal genetic tests and pharmacologic measures to minimize excess risk, v) clinical toxicity may be preceded by asymptomatic systolic and/or diastolic dysfunction that necessitates innovative mechanism-based pharmacologic treatment, and vi) patient-tailored pharmacologic correction of comorbidities is important for both primary and secondary prevention. Active collaboration of physicians with laboratory scientists is much needed for improving management of cardiovascular sequelae of antitumor therapy. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Rhythm control in heart failure patients with atrial fibrillation: contemporary challenges including the role of ablation

Because nonpharmacological interventions likely alter the risks and benefits associated with rhythm control, this paper reviews the role of current rhythm control strategies in atrial fibrillation. This report also focuses on the specific limitations of pharmacological interventions and the utility of percutaneous ablation in this growing population of patients with concomitant atrial fibrillation and heart failure.

Pharmacology at work for cardio-oncology: ranolazine to treat early cardiotoxicity induced by antitumor drugs

Antitumor drugs may cause asymptomatic diastolic dysfunction that introduces a lifetime risk of heart failure or myocardial infarction. Cardio-oncology is the discipline committed to the cardiac surveillance and management of cancer patients and survivors; however, cardio-oncology teams do not always attempt to treat early diastolic dysfunction. Common cardiovascular drugs, such as β blockers or angiotensin-converting enzyme inhibitors or others, would be of uncertain efficacy in diastolic dysfunction. This perspective describes the potential value of ranolazine, an antianginal drug that improves myocardial perfusion by relieving diastolic wall tension and dysfunction. Ranolazine acts by inhibiting the late inward sodium current, and pharmacological reasonings anticipate that antitumor anthracyclines and nonanthracycline chemotherapeutics might well induce anomalous activation of this current. These notions formed the rationale for a clinical study of the efficacy and safety of ranolazine in cancer patients. This study was not designed to demonstrate that ranolazine reduced the lifetime risk of cardiac events; it was designed as a short term proof-of-concept study that probed the following hypotheses: 1) asymptomatic diastolic dysfunction could be detected a few days after patients completed antitumor therapy, and 2) ranolazine was active and safe in relieving echocardiographic and/or biohumoral indices of diastolic dysfunction, measured at 5 weeks or 6 months of ranolazine administration. These facts illustrate the translational value of pharmacology, which goes from identifying therapeutic opportunities to validating hypotheses in clinical settings. Pharmacology is a key to the success of cardio-oncology.

Childhood ataxia: clinical features, pathogenesis, key unanswered questions, and future directions

Childhood ataxia is characterized by impaired balance and coordination primarily because of cerebellar dysfunction. Friedreich ataxia, a form of childhood ataxia, is the most common multisystem autosomal recessive disease. Most of these patients are homozygous for the GAA repeat expansion located on the first intron of the frataxin gene on chromosome 9. Mutations in the frataxin gene impair mitochondrial function, increase reactive oxygen species, and trigger redistribution of iron in the mitochondria and cytosol. Targeted therapies for Friedreich ataxia are undergoing testing. In addition, a centralized database, patient registry, and natural history study have been launched to support clinical trials in Friedreich ataxia. The 2011 Neurobiology of Disease in Children symposium, held in conjunction with the 40th annual Child Neurology Society meeting, aimed to (1) describe clinical features surrounding Friedreich ataxia, including cardiomyopathy and genetics; (2) discuss recent advances in the understanding of the pathogenesis of Friedreich ataxia and developments of clinical trials; (3) review new investigations of characteristic symptoms; and (4) establish clinical and biochemical overlaps in neurodegenerative diseases and possible directions for future basic, translational, and clinical studies.

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.

Damage to mitochondrial complex I during cardiac ischemia reperfusion injury is reduced indirectly by anti-anginal drug ranolazine

Ranolazine, an anti-anginal drug, is a late Na(+) channel current blocker that is also believed to attenuate fatty acid oxidation and mitochondrial respiratory complex I activity, especially during ischemia. In this study, we investigated if ranolazine's protective effect against cardiac ischemia/reperfusion (IR) injury is mediated at the mitochondrial level and specifically if respiratory complex I (NADH Ubiquinone oxidoreductase) function is protected. We treated isolated and perfused guinea pig hearts with ranolazine just before 30 min ischemia and then isolated cardiac mitochondria at the end of 30 min ischemia and/or 30 min ischemia followed by 10 min reperfusion. We utilized spectrophotometric and histochemical techniques to assay complex I activity, Western blot analysis for complex I subunit NDUFA9, electron paramagnetic resonance for activity of complex I Fe-S clusters, enzyme linked immuno sorbent assay (ELISA) for determination of protein acetylation, native gel histochemical staining for respiratory supercomplex assemblies, and high pressure liquid chromatography for cardiolipin integrity; cardiac function was measured during IR. Ranolazine treated hearts showed higher complex I activity and greater detectable complex I protein levels compared to untreated IR hearts. Ranolazine treatment also led to more normalized electron transfer via Fe-S centers, supercomplex assembly and cardiolipin integrity. These improvements in complex I structure and function with ranolazine were associated with improved cardiac function after IR. However, these protective effects of ranolazine are not mediated by a direct action on mitochondria, but rather indirectly via cytosolic mechanisms that lead to less oxidation and better structural integrity of complex I.

Medical therapy versus myocardial revascularization in chronic coronary syndrome and stable angina

Coronary artery disease is a leading cause of death in the United States. Angina is encountered frequently in clinical practice. Effective management of patients with coronary artery disease and stable angina should consist of therapy aimed at symptom control and reduction of adverse clinical outcomes. Therapeutic options for angina include antianginal drugs: nitrates, beta-blockers, calcium channel blockers, ranolazine, and myocardial revascularization. Recent trials have shown that although revascularization is slightly better in controlling symptoms, optimal medical therapy that includes aggressive risk factor modification is equally effective in reducing the risk of future coronary events and death. On the basis of the available data, it seems appropriate to prescribe optimal medical therapy in most patients with coronary artery disease and stable angina, and reserve myocardial revascularization for selected patients with disabling symptoms despite optimal medical therapy.

Evolving approaches to the management of heart failure with preserved ejection fraction in patients with coronary artery disease

OPINION STATEMENT

Coronary artery disease (CAD) is a major cause of heart failure with preserved ejection fraction (HFpEF). In studies of HFpEF, the reported prevalence of CAD varies widely, which may be the result of inconsistent definitions of CAD, geographic and ethnic differences in CAD burden, varying definitions of HFpEF (including different cutoffs for "preserved ejection fraction"), and differences in study design. Despite these limitations, pooled analysis of prospective HFpEF studies demonstrates that CAD is common in HFpEF, with an estimated prevalence of approximately 50%. Based on available data, patients with signs and symptoms of heart failure who have preserved left ventricular ejection fraction and evidence of CAD (HFpEF-CAD) most likely comprise a distinct etiologic and pathophysiologic subset of HFpEF. Therefore, future clinical trials in HFpEF should a priori stratify by CAD or specifically target patients with CAD, strategies that may improve the disappointing track record of therapies tested in HFpEF. The combination of systematic evaluation and management of CAD in HFpEF, along with promising future therapies for HFpEF-CAD, may lead to improved outcomes for this challenging clinical syndrome.

Emerging clinical role of ranolazine in the management of angina

Chronic stable angina is an exceedingly prevalent condition with tremendous clinical, social, and financial implications. Traditional medical therapy for angina consists of beta-blockers, calcium channel blockers, and nitrates. These agents decrease myocardial oxygen demand and ischemia by reducing heart rate, lowering blood pressure, and/or optimizing ventricular loading characteristics. Unique in its mechanism of action, ranolazine is the first new antianginal agent approved for use in the US for chronic angina in over 25 years. By inhibiting the late inward sodium current (I(Na)), ranolazine prevents pathologic intracellular calcium accumulation that leads to ischemia, myocardial dysfunction, and electrical instability. Ranolazine has been proven in multiple clinical trials to reduce the symptoms of angina safely and effectively and to improve exercise tolerance in patients with symptomatic coronary heart disease. These benefits occur without reduction in heart rate and blood pressure or increased mortality. Although ranolazine prolongs the QT(c), experimental data indicate that ranolazine may actually be antiarrhythmic. In a large acute coronary syndrome clinical trial, ranolazine reduced the incidence of supraventricular tachycardia, ventricular tachycardia, new-onset atrial fibrillation, and bradycardic events. Additional benefits of ranolazine under investigation include reductions in glycosylated hemoglobin levels and improved left ventricular function. Ranolazine is a proven antianginal medication in patients with symptomatic coronary heart disease, and should be considered as an initial antianginal agent for those with hypotension or bradycardia.

Improvement in Left Ventricular Systolic and Diastolic Performance During Ranolazine Treatment in Patients With Stable Angina

Purpose: Ranolazine is a novel antianginal medication that acts by ameliorating disturbed sodium and calcium homeostasis. By preventing myocyte sodium and calcium overload, ranolazine also have potential beneficial effects on myocardial function. Experimental models support this concept, as do 2 small studies in human participants receiving ranolazine intravenously. We evaluated changes in parameters of left ventricular function in stable angina patients treated with oral ranolazine. Methods: Twenty-two participants were enrolled with Doppler echocardiography performed at baseline and a mean of 2 months after initiation of treatment. Results: Global left ventricular function, as assessed by the myocardial performance index, was significantly improved on drug therapy (P < .0001). This was due to improvement in both diastolic and systolic parameters. Of 21 patients, 17 reported less angina and 8 patients reported an increase in activity level. Conclusions: We report improved parameters of left ventricular function in response to ranolazine as used in the clinical setting.

The utility of cardiopulmonary exercise testing in the assessment of suspected microvascular ischemia

Evidence demonstrating the potential value of cardiopulmonary exercise testing (CPET) to accurately detect myocardial ischemia secondary to macro-vascular disease is beginning to emerge. Despite distinct mechanisms mediating ischemia in micro-vascular and macrovascular coronary artery disease (CAD), the net physiologic effect of exercise-induced left ventricular (LV) dysfunction is common to both. The abnormal physiologic response to CPET may, therefore, be similar in patients with macro- and micro-vascular ischemia. The following case report describes the CPET abnormalities in a patient with suspected microvascular CAD and the subsequent improvement in LV function following three weeks of medical therapy with the anti-ischemic drug ranolazine.