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Biomedical subjects

Arthur M Feldman

Publications and source records attributed to Arthur M Feldman.

At least 37 records · Page 2Linked to original sources

Implantable cardioverter defibrillators and cardiac resynchronization therapy in patients with left ventricular dysfunction: randomized trial evidence through 2004.

Although many studies have shown that implantable cardioverter defibrillator (ICD) therapy improves the survival of patients with significant left ventricular dysfunction, the magnitude of effectiveness of ICD therapy in clinically defined subgroups remains uncertain. Similarly, although studies have shown an improvement in patients' hemodynamics and quality of life with cardiac resynchronization therapy (CRT), there is a continuing uncertainty about the effect of CRT on patients' survival and the magnitude of improvement in quality of life with this therapy. On August 24, 2004, an ad hoc group of experts representing clinical cardiovascular medicine, biostatistics, economics, and health policy were joined by representatives of the Food and Drug Administration, Centers for Medicare and Medicaid Services (Baltimore, Md), Agency for Healthcare Research and Quality (Rockville, Md), and the device industry for a 1-day round table to review the available clinical trial evidence on the effect of ICD therapy in the primary prevention of sudden cardiac death and the effect of CRT in patients with congestive heart failure. The meeting was organized by the Duke Clinical Research Institute, Durham, NC, and funded in part by the Agency for Healthcare Research and Quality. This document summarizes the evidence reviewed at that meeting and the discussions of that evidence.

Death, Sudden, Cardiac↗

Treating heart failure with enhanced external counterpulsation (EECP): design of the Prospective Evaluation of EECP in Heart Failure (PEECH) trial.

BACKGROUND: Enhanced external counterpulsation (EECP) treatment can improve exercise tolerance in patients with ischemic heart disease; however, the possible benefits of EECP in patients with stable heart failure (HF) and left ventricular dysfunction (LVD) are unclear. An open pilot study showed significant increases in exercise tolerance in HF patients undergoing EECP. Thus a larger, controlled study of EECP in patients with stable HF (New York Heart Association [NYHA] classes II and III) and LVD was undertaken. METHODS AND RESULTS: The PEECH trial is a controlled, randomized, single-blind, parallel-group, multicenter study of 187 patients with symptomatic but stable HF (NYHA classes II and III) and an LV ejection fraction < or =35% was designed to assess the efficiency of EECP in patients with stable HF. Medical therapy is optimized in all patients based on the recommendations of the Heart Failure Society of America ("Usual Care"), and then randomized between 2 treatment groups; UC or EECP (35 hours over 7 weeks). CONCLUSION: Efficacy measures include standard exercise tolerance tests on a treadmill (modified Naughton protocol), with measurements of peak oxygen uptake and exercise duration time; quality of life questionnaires; NYHA classification; and neurohormonal markers of HF.

Counterpulsation↗

Rationale and design of the enoximone clinical trials program.

BACKGROUND: Chronic heart failure is a disease syndrome characterized in its advanced stages by a poor quality of life, frequent hospitalizations, and a high risk of mortality. In advanced and ultra-advanced chronic heart failure, many treatment options, such as cardiac transplantation and mechanical devices, are severely limited by availability and cost. Short-term Phase II clinical trials suggest that low-dose oral inotropic therapy with enoximone may improve hemodynamics and exercise capacity, without adversely affecting mortality, in selected subjects with advanced chronic heart failure. Based on these data, the ability of enoximone to deliver safe and efficacious palliative treatment of advanced/ultra-advanced chronic heart failure is being evaluated in Phase III clinical trials. METHODS AND RESULTS: The Enoximone Clinical Trials Program is a series of 4 clinical trials designed to evaluate the safety and efficacy of oral enoximone in advanced chronic heart failure. ESSENTIAL I and II (The Studies of Oral Enoximone Therapy in Advanced Heart Failure) will investigate the effects of oral enoximone on all-cause mortality and cardiovascular hospitalization, submaximal exercise capacity, and quality of life in subjects with New York Heart Association Class III/IV chronic heart failure. EMOTE (Oral Enoximone in Intravenous Inotrope-Dependent Subjects) will evaluate the potential of oral enoximone to wean subjects with ultra-advanced chronic heart failure from chronic intravenous inotropic therapy to which they have been shown to be dependent. EMPOWER (Enoximone Plus Extended-Release Metoprolol Succinate in Subjects with Advanced Chronic Heart Failure) will explore the potential of enoximone to increase the tolerability of continuous release metoprolol in subjects shown previously to be hemodynamically intolerant to beta-blocker treatment. CONCLUSION: These studies are Phase III, multicenter, randomized, double-blinded, placebo-controlled trials designed to test the general hypothesis that chronic oral administration of low doses of enoximone can produce beneficial effects in subjects with advanced or ultra-advanced chronic heart failure.

Administration, Oral↗

17 Beta-estradiol improves survival in male mice with cardiomyopathy induced by cardiac-specific tumor necrosis factor-alpha overexpression.

A transgenic mouse model of congestive heart failure (CHF) consequent to cardiac-specific overexpression of tumor necrosis factor-alpha (TNF-alpha) (TNF1.6) displays marked sex-related phenotypic differences. To clarify the potential contributions of estrogen to these sex-specific differences, male TNF1.6 mice were treated with 17beta- estradiol (E2). E2 treatment started at 25 +/- 1 days old (group A), but not at 36 +/- 2 days old (group B), significantly improved survival rate (p < 0.05). Furthermore, ventricular weight/body weight ratio was significantly decreased by E2 treatment in group A (p < 0.05). Echocardiography revealed that E2-treated hearts in group A exhibited less left ventricular dilatation (p < 0.05) relative to untreated male TNF1.6 mice (control). Moreover, in group A, E2 treatment partially reversed basal and isoproterenol-stimulated fractional shortening in TNF1.6 mice (p < 0.05). The cardiac content of TNF-alpha and interleukin-1beta (IL-1beta) was not changed by E2 treatment regardless of the timing of treatment. Thus, E2 exposure prior to puberty can limit the severity of cardiomyopathy in male TNF1.6 mice.

Animals↗

Pharmacogenetic interactions between angiotensin-converting enzyme inhibitor therapy and the angiotensin-converting enzyme deletion polymorphism in patients with congestive heart failure.

OBJECTIVES: We evaluated the interaction of angiotensin-converting enzyme (ACE) inhibitor therapy with the effect of the ACE D/I polymorphism on heart failure survival. BACKGROUND: The ACE deletion allele, ACE-D, is associated with increased ACE activity. The utilization of ACE genotyping to predict the impact of ACE inhibitor dose has not been previously evaluated. METHODS: We prospectively studied 479 subjects with systolic dysfunction (left ventricular ejection fraction 0.25 +/- 0.08). Subjects were divided on the basis of ACE inhibitor therapy into low dose ( 50%, n = 201), or those receiving angiotensin receptor antagonists (n = 51). Patients were genotyped for the ACE D/I polymorphism, followed to the end point of death or cardiac transplantation, and transplant-free survival compared by genotype. RESULTS: The ACE-D allele was associated with an increased risk of events (p = 0.026). In analysis by ACE inhibitor dose, this effect was primarily in the low-dose group (1-year percent event-free survival: II/ID/DD = 86/77/71,2-year = 79/66/59, p = 0.032). In the standard-dose group, the impact was markedly diminished (1-year: II/ID/DD = 91/81/80, 2-year: 77/70/71, p = 0.64). The impact of beta-blockers and high dose ACE inhibitors was greatest in subjects with the ACE DD genotype (p = 0.001) and was less apparent with the II and ID genotypes (p = 0.38). CONCLUSIONS: Higher doses of ACE inhibitors diminished the impact of the ACE-D allele, and the benefits of beta-blockers and high-dose ACE inhibitors appeared maximal for DD patients. Determination of ACE genotype may help target therapy for patients with heart failure.

Adrenergic beta-Antagonists↗

Phospholamban gene ablation improves calcium transients but not cardiac function in a heart failure model.

UNLABELLED: Decreased amplitude and slower kinetics of cardiomyocyte intracellular calcium (Ca(i)(2+)) transients may underlie the diminished cardiac function observed in heart failure. These alterations occur in humans and animals with heart failure, including the TNF1.6 mouse model, in which heart failure arises from cardiac-specific overexpression of tumor necrosis factor alpha (TNF alpha). OBJECTIVE: Since ablation of phospholamban expression (PLBKO) removes inhibition of the sarcoplasmic reticulum (SR) Ca(2+) pump, enhances SR Ca(2+) uptake and increases contractility, we assessed whether ablation of phospholamban expression could improve cardiac function, limit remodeling, and improve survival in the TNF1.6 model of heart failure. METHODS: We bred PLBKO with TNF1.6 mice and characterized the progeny for survival, cardiac function (echocardiography), cardiac remodeling (hypertrophy, dilation, fibrosis), and Ca(2+)(i) transients and contractile function of isolated cardiomyocytes. RESULTS: PLB ablation did not improve survival, cardiac function, or limit cardiac chamber dilation and hypertrophy in TNF1.6 mice (TKO mice). However, contractile function and Ca(2+)(i) transients (amplitude and kinetics) of isolated TKO cardiomyocytes were markedly enhanced. This discordance between unimproved cardiac function, and enhanced Ca(2+)(i) cycling and cardiomyocyte contractile parameters may arise from a continued overexpression of collagen and decreased expression of gap junction proteins (connexin 43) in response to chronic TNF alpha stimulation. CONCLUSIONS: Enhancement of intrinsic cardiomyocyte Ca(2+)(i) cycling and contractile function may not be sufficient to overcome several parallel pathophysiologic processes present in the failing heart.

Animals↗

Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure.

BACKGROUND: We tested the hypothesis that prophylactic cardiac-resynchronization therapy in the form of biventricular stimulation with a pacemaker with or without a defibrillator would reduce the risk of death and hospitalization among patients with advanced chronic heart failure and intraventricular conduction delays. METHODS: A total of 1520 patients who had advanced heart failure (New York Heart Association class III or IV) due to ischemic or nonischemic cardiomyopathies and a QRS interval of at least 120 msec were randomly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy (diuretics, angiotensin-converting-enzyme inhibitors, beta-blockers, and spironolactone) alone or in combination with cardiac-resynchronization therapy with either a pacemaker or a pacemaker-defibrillator. The primary composite end point was the time to death from or hospitalization for any cause. RESULTS: As compared with optimal pharmacologic therapy alone, cardiac-resynchronization therapy with a pacemaker decreased the risk of the primary end point (hazard ratio, 0.81; P=0.014), as did cardiac-resynchronization therapy with a pacemaker-defibrillator (hazard ratio, 0.80; P=0.01). The risk of the combined end point of death from or hospitalization for heart failure was reduced by 34 percent in the pacemaker group (P<0.002) and by 40 percent in the pacemaker-defibrillator group (P<0.001 for the comparison with the pharmacologic-therapy group). A pacemaker reduced the risk of the secondary end point of death from any cause by 24 percent (P=0.059), and a pacemaker-defibrillator reduced the risk by 36 percent (P=0.003). CONCLUSIONS: In patients with advanced heart failure and a prolonged QRS interval, cardiac-resynchronization therapy decreases the combined risk of death from any cause or first hospitalization and, when combined with an implantable defibrillator, significantly reduces mortality.

Adrenergic beta-Antagonists↗

Tumor necrosis factor receptors 1 and 2 differentially regulate survival, cardiac dysfunction, and remodeling in transgenic mice with tumor necrosis factor-alpha-induced cardiomyopathy.

BACKGROUND: Tumor necrosis factor (TNF)-alpha plays a pathophysiological role in heart failure. Although both TNF receptor 1 (TNFR1) and 2 (TNFR2) are present in the heart, comparatively little is known about the role of TNFR2. METHODS AND RESULTS: We bred TNFR1-knockout (KO) or TNFR2KO mice to transgenic (TG) mice with cardiac-specific overexpression of TNF-alpha and analyzed resultant progeny. Six groups of male and female mice were studied: wild type (WT) with wild receptors (WT/W), TG with wild receptors (TG/W), TG with heterozygous receptor KO (TG/R1+/- or TG/R2+/-), and TG with homozygous receptor KO (TG/R1-/- or TG/R2-/-). Both male and female TG mice displayed cardiac hypertrophy, dilation, and reduced cardiac function. Male TG mice were more severely affected than genotypically matched females and died of heart failure at a younger age. Survival, cardiac function, and remodeling of TG/R1+/- and TG/R1-/- mice were improved relative to TG/W mice in both males and females. However, the survival of female TG/R2+/- and TG/R2-/- mice was worse than that of TG/W mice, with increased left ventricular dimension and left ventricular weight/body weight ratios. The cardiac TNF-alpha protein level was upregulated in TG/R1-/- and TG/R2-/- compared with TG/W mice, whereas the level of TNF receptors was not downregulated in TG/W relative to WT/W mice. CONCLUSIONS: Ablation of the TNFR2 gene exacerbates heart failure and reduces survival, whereas ablation of TNFR1 blunts heart failure and improves survival. Signaling via TNFR2 may play a cardioprotective role in the pathogenesis of cytokine-mediated heart failure.

Animals↗

Assessment of infarct size and myocardial function in mice using transesophageal echocardiography.

BACKGROUND: Because transthoracic echocardiography (TTE) has significant limitations in assessing changes consequent to myocardial infarction (MI) in mice, we studied two novel methods to characterize such infarcts. METHODS: Large MIs were produced by proximal left coronary artery ligation, and small MIs by distal left coronary artery ligation. Serum cardiac troponin I levels were measured 24 hours postoperatively. At 2 weeks, mice underwent transesophageal echocardiography (TEE) and TTE. Infarct sizes were determined histologically. RESULTS: Surviving mice were classified according to infarct size. TEE identified all histologically proven large infarcts, and 4 of 5 small infarcts. TTE identified 4 of 5 large infarcts, but only 1 of 5 small infarcts. TEE-derived fractional area change, but not TTE-estimated left ventricular fractional shortening, was significantly different among large, small, and sham infarcts. Cardiac troponin I showed excellent correlation with infarct size and mortality. CONCLUSIONS: Cardiac troponin I was found to predict infarct size and mortality, whereas TEE proved superior to TTE in determining infarct size and/or myocardial function in a murine MI model. These tools should provide more accurate assessments in preclinical studies of ischemic cardiomyopathy.

Analysis of Variance↗

Gene expression profiling during the transition to failure in TNF-alpha over-expressing mice demonstrates the development of autoimmune myocarditis.

Transgenic mice with cardiac-specific over-expression of tumor necrosis factor-alpha (TNF1.6) progress to dilated heart failure. A significant inflammatory response precedes functional deterioration, and may contribute to cardiac damage in this model. To evaluate the underlying molecular mechanisms, we assessed the gene expression in six groups of mouse hearts defined by age, gender, and phenotype (n = 3/group) using Affymetrix microarray analysis. Phenotype was defined as compensated (in young TNF1.6) or decompensated (in older TNF1.6) via echocardiogram. Of the >1000 transcripts altered in the compensated hearts (fold change > 2, P < 0.05 vs. wild-type (WT)), 102 were identified as immune response genes, 20 of which function in antigen presentation and processing. When comparing the compensated and decompensated hearts, >50 genes were differentially regulated, including seven immunoglobulin genes. Real-time reverse transcriptase-polymerase chain reaction and cDNA microarray confirmed the Affymetrix data. Mac3+ macrophages, CD4+ T and CD45/B220+ B-cells were identified in both compensated and decompensated hearts. However, a large amount of IgG was found deposited in areas devoid of B-lymphocytes in the myocardium of decompensated TNF1.6 mice; no such accumulation was seen in the compensated or age-matched controls. Furthermore, nuclei density analyses showed a two-fold increase in the myocardium of both compensated and decompensated TNF1.6 mice (vs. WT). This study suggests that TNF-alpha over-expression activates not only the inflammatory response, but also humoral immune responses within the transgenic hearts. The autoimmune response occurs concomitantly with cardiac decompensation and may participate in triggering the transition to failure in TNF1.6 mice.

Animals↗

Use of a wearable defibrillator in terminating tachyarrhythmias in patients at high risk for sudden death: results of the WEARIT/BIROAD.

The automatic ICD improves survival in patients with a history of sudden cardiac arrest. However, some patients do not meet the guidelines for ICD implantation or are unable to receive an implantable device. This study tested the hypothesis that these patients could benefit from a wearable cardioverter defibrillator. Patients with symptomatic heart failure and an ejection fraction of <0.30 (WEARIT Study) or patients having complications associated with high risk for sudden death after a myocardial infarction or bypass surgery not receiving an ICD for up to 4 months (BIROAD Study) were enrolled into two studies. After a total of 289 patients had been enrolled in the trial (177 in WEARIT and 112 in BIROAD), prespecified safety and effectiveness guidelines had been met. Six (75%) of eight defibrillation attempts were successful. Six inappropriate shock episodes occurred during 901 months of patient use (0.67% unnecessary shocks per month of use). Twelve deaths occurred during the study 6 sudden deaths: 5 not wearing and 1 incorrectly wearing the device). Most patients tolerated the device although 68 patients quit due to comfort issues or adverse reactions. The results of the present study suggest that a wearable defibrillator is beneficial in detecting and effectively treating ventricular tachyarrhythmias in patients at high risk for sudden death who are not clear candidates for an ICD and may be useful as a bridge to transplantation or ICD in some patients.

Death, Sudden, Cardiac↗

Inhibition of tumor necrosis factor receptor-1-mediated pathways has beneficial effects in a murine model of postischemic remodeling.

The aim of the present study was to investigate the importance of tumor necrosis factor (TNF)-alpha receptor-1 (TNFR1)-mediated pathways in a murine model of myocardial infarction and remodeling. One hundred and ninety-four wild-type (WT) and TNFR1 gene-deleted (TNFR1KO) mice underwent left coronary artery ligation to induce myocardial infarction. On days 1, 3, 7, and 42, mice underwent transesophageal echocardiography. Hearts were weighed, and the left ventricle (LV) was assayed for matrix metalloproteinase (MMP)-2 and -9 activity and for tissue inhibitor of MMP (TIMP)-1 and -2 expression. Deletion of the TNFR1 gene substantially improved survival because no deaths were observed in TNFR1KO mice versus 56.4% and 18.2% in WT males and females, respectively (P < 0.002). At 42 days, LV remodeling, assessed by LV function (fractional area change of 31.9 +/- 7.9%, 32.2 +/- 7.7%, and 21.6 +/- 7.1% in TNFR1KO males, TNFR1KO females, and WT females, respectively, P < 0.04), and hypertrophy (heart weight-to-body weight ratios of 5.435 +/- 0.986, 5.485 +/- 0.677, and 6.726 +/- 0.704 mg/g, P < 0.04) were ameliorated in TNFR1KO mice. MMP-9 activity was highest at 3 days postinfarction and was highest in WT males (1.9 +/- 0.4 4, 3.6 +/- 0.24, 1.15 +/- 0.28, and 1.3 +/- 1.2 ng/100 microg protein, respectively, in TNFR1KO males, WT males, TNFR1KO females, and WT females, respectively, P < 0.002), whereas at 3 days TIMP-1 mRNA fold upregulation compared with type- and sex-matched controls was lowest in WT males (138.32 +/- 13.05, 46.74 +/- 5.43, 186.09 +/- 28.07, and 101.76 +/- 22.48, respectively, P < 0.002). MMP-2 and TIMP-2 increased similarly in all infarcted groups. These findings suggest that the benefits of TNFR1 ablation might be attributable at least in part to the attenuation of cytokine-mediated imbalances in MMP-TIMP activity.

Animals↗

Clinical characteristics of vesnarinone.

Congestive heart failure is a common condition with a poor prognosis. Its high rates of morbidity and mortality produce a huge societal burden. Current pharmacological treatment approaches are based on angiotensin-converting enzyme inhibitors, diuretics and digoxin, but up to 5% of patients may have refractory disease with persistent symptoms at rest. Such patients with advanced-stage disease may be candidates for treatment with the novel agent vesnarinone, a mixed phosphodiesterase inhibitor and ion-channel modifier that has modest, dose-dependent, positive inotropic activity, but minimal negative chronotropic activity. Vesnarinone improves ventricular performance most in patients with the worst degree of heart failure. However, before the initiation of vesnarinone therapy, risk-benefit profiles in individual patients should be considered, because in two large-scale studies [i.e. of the high dosage used in the Vesnarinone Study Group Trial (VSGT), and of both dosages used in the Vesnarinone Trial (VEST)] a dose-dependent increase in mortality was identified for vesnarinone 30-120 mg/day. The two studies also found significant vesnarinone-induced, short-term improvements in quality of life (QOL) in patients with refractory end-stage heart failure. Such patients are the most willing to trade-off a slightly increased risk of mortality for improved QOL. It is thus in these patients with refractory end-stage heart failure that vesnarinone may ultimately establish an important treatment role. However, detailed further investigation of the overall place of vesnarinone in heart failure management, with particular reference to the clinical potential of vesnarinone plus beta-blocker combination therapy, for example, is certainly warranted.

Algorithms↗

Is there any future for tumor necrosis factor antagonists in chronic heart failure?

Over the past decade, a large number of studies have demonstrated that tumor necrosis factor-alpha (TNFalpha) plays an important role in the development of heart failure. Indeed, administration of TNFalpha to experimental animals and transgenic over-expression of TNFalpha replicate the heart failure phenotype. Furthermore, attenuation of the biologic activity of TNFalpha abrogates the development of heart failure in model systems. These pre-clinical studies, suggested that anti-cytokine therapy could prove beneficial in the treatment of patients with heart failure. While early studies supported this hypothesis, anti-TNF strategies have not demonstrated salutary benefits in large, multicenter randomized and placebo-controlled clinical trials in patients with symptomatic heart failure. This finding was disappointing. However, recent studies might provide clarification of this conundrum. For example, the failure to elicit beneficial effects with anti-cytokine therapy might be explained by novel pharmacogenomic or pharmacodynamic effects, the design of the Phase III clinical trials, or discordance between animal models and the human condition. Thus, appropriately designed clinical trials and newer anticytokine agents may demonstrate benefit.

Animals↗