Adrenergic receptor polymorphisms and prevention of ventricular arrhythmias with bucindolol in patients with chronic heart failure.

BACKGROUND: ß-blockers prevent cardiac arrhythmias in patients with chronic heart failure and reduced left ventricular ejection fraction, including ventricular tachycardia/ventricular fibrillation (VT/VF). We hypothesized that prevention of ventricular arrhythmias by the ß-blocker/sympatholytic agent bucindolol is influenced by genetic variation in adrenergic receptors. METHODS AND RESULTS: From a substudy of the ß-Blocker Evaluation of Survival Trial (n=1040), we identified those with the high functioning 389Arg versus the lower function 389Gly ß(1) adrenergic receptor variant, and the loss of function α(2c)322-325 adrenergic receptor deletion versus the 322 to 325 wild-type (Wt)/deletion variant. VT/VF was recorded on case report forms as an adverse event. There were 493 Arg 389 ß(1) receptor homozygotes (ß(1)389 Arg/Arg) versus 547 Gly389 carriers and 207 α(2c)322-325 deletion carriers versus 833 homozygous Wts (α(2c)322-325 Wt/Wt). In all genotypes bucindolol was associated with a lower incidence of VT/VF (subhazard ratio, 0.42 [0.27-0.64]; P=0.00006). Bucindolol reduced VT/VF in ß(1)389 Arg homozygotes (subhazard ratio, 0.26 [0.14-0.50]; P=0.00005) but not in ß(1)389 Gly carriers (subhazard ratio, 0.60 [0.34-1.07]; P=0.09). For genotype combinations, the α(2c)322-325 polymorphism altered the VT/VF bucindolol response in ß1389 Gly carriers, with α(2c) deletion genotypes associated with complete efficacy loss. A test of interaction was statistically significant (P=0.028) for the treatment group and a ß(1)389/α(2c)322-325 three genotype construct, effectively identifying patients who exhibited enhanced response, no substantial response modification and loss of response. CONCLUSIONS: Bucindolol prevents VT/VF in subjects with heart failure and reduced left ventricular ejection fractions, and this effect is modulated by ß(1)389 Arg/Gly and α(2c)322-325 Wt/deletion adrenergic receptor polymorphisms.

A personalized BEST: characterization of latent clinical classes of nonischemic heart failure that predict outcomes and response to bucindolol.

BACKGROUND: Heart failure patients with reduced ejection fraction (HFREF) are heterogenous, and our ability to identify patients likely to respond to therapy is limited. We present a method of identifying disease subtypes using high-dimensional clinical phenotyping and latent class analysis that may be useful in personalizing prognosis and treatment in HFREF. METHODS: A total of 1121 patients with nonischemic HFREF from the ß-blocker Evaluation of Survival Trial were categorized according to 27 clinical features. Latent class analysis was used to generate two latent class models, LCM A and B, to identify HFREF subtypes. LCM A consisted of features associated with HF pathogenesis, whereas LCM B consisted of markers of HF progression and severity. The Seattle Heart Failure Model (SHFM) Score was also calculated for all patients. Mortality, improvement in left ventricular ejection fraction (LVEF) defined as an increase in LVEF ≥5% and a final LVEF of 35% after 12 months, and effect of bucindolol on both outcomes were compared across HFREF subtypes. Performance of models that included a combination of LCM subtypes and SHFM scores towards predicting mortality and LVEF response was estimated and subsequently validated using leave-one-out cross-validation and data from the Multicenter Oral Carvedilol Heart Failure Assessment Trial. RESULTS: A total of 6 subtypes were identified using LCM A and 5 subtypes using LCM B. Several subtypes resembled familiar clinical phenotypes. Prognosis, improvement in LVEF, and the effect of bucindolol treatment differed significantly between subtypes. Prediction improved with addition of both latent class models to SHFM for both 1-year mortality and LVEF response outcomes. CONCLUSIONS: The combination of high-dimensional phenotyping and latent class analysis identifies subtypes of HFREF with implications for prognosis and response to specific therapies that may provide insight into mechanisms of disease. These subtypes may facilitate development of personalized treatment plans.

Combinatorial pharmacogenetic interactions of bucindolol and ß1, α2C adrenergic receptor polymorphisms.

BACKGROUND: Pharmacogenetics involves complex interactions of gene products affecting pharmacodynamics and pharmacokinetics, but there is little information on the interaction of multiple genetic modifiers of drug response. Bucindolol is a ß-blocker/sympatholytic agent whose efficacy is modulated by polymorphisms in the primary target (ß(1) adrenergic receptor [AR] Arg389 Gly on cardiac myocytes) and a secondary target modifier (α(2C) AR Ins [wild-type (Wt)] 322-325 deletion [Del] on cardiac adrenergic neurons). The major allele homozygotes and minor allele carriers of each polymorphism are respectively associated with efficacy enhancement and loss, creating the possibility for genotype combination interactions that can be measured by clinical trial methodology. METHODOLOGY: In a 1,040 patient substudy of a bucindolol vs. placebo heart failure clinical trial, we tested the hypothesis that combinations of ß(1)389 and α(2C)322-325 polymorphisms are additive for both efficacy enhancement and loss. Additionally, norepinephrine (NE) affinity for ß(1)389 AR variants was measured in human explanted left ventricles. PRINCIPAL FINDINGS: The combination of ß(1)389 Arg+α(2C)322-325 Wt major allele homozygotes (47% of the trial population) was non-additive for efficacy enhancement across six clinical endpoints, with an average efficacy increase of 1.70-fold vs. 2.32-fold in ß(1)389 Arg homozygotes+α(2C)322-325 Del minor allele carriers. In contrast, the minor allele carrier combination (13% subset) exhibited additive efficacy loss. These disparate effects are likely due to the higher proportion (42% vs. 8.7%, P = 0.009) of high-affinity NE binding sites in ß(1)389 Arg vs. Gly ARs, which converts α(2C)Del minor allele-associated NE lowering from a therapeutic liability to a benefit. CONCLUSIONS: On combination, the two sets of AR polymorphisms 1) influenced bucindolol efficacy seemingly unpredictably but consistent with their pharmacologic interactions, and 2) identified subpopulations with enhanced (ß(1)389 Arg homozygotes), intermediate (ß(1)389 Gly carriers+α(2C)322-325 Wt homozygotes), and no (ß(1)389 Gly carriers+α(2C)322-325 Del carriers) efficacy.

Determination of hospitalization type by investigator case report form or adjudication committee in a large heart failure clinical trial (ß-Blocker Evaluation of Survival Trial [BEST]).

BACKGROUND: End point committees are routinely used to adjudicate efficacy and safety end points in clinical trials. The 2,708-patient ß-Blocker Evaluation of Survival Trial (BEST) originally determined hospitalization type via investigator case report forms (CRFs), which captured whether a hospitalization was due to worsening heart failure (HF). Recently, the BEST End Points Committee (EPC) completed a blinded adjudication of all hospitalizations, allowing a comparison of the CRF method to the EPC method of determining hospitalization type. We sought to compare the investigator-determined mode of hospitalizations with the adjudicated events, to quantify the degree of agreement, and to compare the clinical trial results by method of event classification. METHODS: The BEST EPC reviewed all 5,086 hospitalizations that occurred in BEST. Events were identified using investigator-reported hospitalizations, as well as those documented by FDA Form 3500 (MedWatch) reports. RESULTS: The investigators identified more HF hospitalization events than adjudication (2,466 vs 1,729, P < .0001, paired analysis). Eight hundred thirty-four (34%) HF hospitalizations identified in CRFs were not confirmed by adjudication. Ninety-seven (6%) adjudicated events were not identified by the investigator reported method. One thousand six hundred thirty-two events were similarly identified by both methods. CONCLUSIONS: The EPC adjudication identified fewer HF hospitalizations than did the investigator reported method with no change in the hazard ratio for this end point. Our findings suggest that independent end point committees may improve reliability through reduced variance, thus providing similar outcome results with fewer events and no increase in CIs.

An alpha2C-adrenergic receptor polymorphism alters the norepinephrine-lowering effects and therapeutic response of the beta-blocker bucindolol in chronic heart failure.

BACKGROUND: Adrenergic activation is an important determinant of outcomes in chronic heart failure. Adrenergic activity is regulated in part by prejunctional alpha(2C)-adrenergic receptors (ARs), which exhibit genetic variation in humans. Bucindolol is a novel beta-AR blocking agent that also lowers systemic norepinephrine and thus is also a sympatholytic agent. This study investigated whether alpha(2C)-AR polymorphisms affect sympatholytic effects of bucindolol in patients with heart failure. METHODS AND RESULTS: In the beta-Blocker Evaluation of Survival Trial, adrenergic activation was estimated by systemic venous norepinephrine measured at baseline, 3 months, and 12 months posttreatment in patients treated with placebo or bucindolol. In the beta-Blocker Evaluation of Survival Trial AR polymorphism substudy, DNA was collected from 1040 of the 2708 randomized patients, and alpha(2C)-AR gene polymorphisms (alpha(2C) Del322-325 or the wild-type counterpart) were measured by polymerase chain reaction and gel electrophoresis. Patients who were alpha(2C) Del carriers (heterozygotes or homozygotes) exhibited a much greater sympatholytic response to bucindolol (decrease in norepinephrine at 3 months of 153+/-57 pg/mL, P=0.012 compared with placebo versus decrease of 50+/-13 pg/mL in alpha(2C) wild type, P=0.0005 versus placebo; P=0.010 by interaction test). alpha(2C) Del carriers had no evidence of a favorable survival benefit from bucindolol (mortality compared with placebo hazard ratio, 1.09; 95% CI, 0.57 to 2.08; P=0.80), whereas bucindolol-treated subjects who were wild type for the alpha(2C)-AR had a 30% reduction in mortality (hazard ratio, 0.70; 95% CI, 0.51 to 0.96; P=0.025). CONCLUSIONS: In the beta-Blocker Evaluation of Survival Trial AR polymorphism substudy, the norepinephrine lowering and clinical therapeutic responses to bucindolol were strongly influenced by alpha(2C) receptor genotype.

Left ventricular assist device as bridge to transplantation does not adversely affect one-year heart transplantation survival.

OBJECTIVE: Left ventricular assist devices are increasingly used as a bridge to transplantation. It remains unclear whether the use of pretransplant left ventricular assist devices adversely affects short-term survival after cardiac transplantation. METHODS: A retrospective review of 317 consecutive patients undergoing cardiac transplantation at an academic center between 1986 and 2006 was undertaken. Left ventricular assist devices were used pretransplant in 23 of these 317 patients, and 294 patients did not require left ventricular assist device support. Patients with a left ventricular assist device were supported with a Heartmate VE or Heartmate XVE (Thoratec Corp, Pleasanton, Calif). Kaplan-Meier survival estimates were compared between the left ventricular assist device group and the non-left ventricular assist device group using the log-rank test. In addition, occurrence of death was analyzed between the 2 groups with a chi-square analysis. The results are expressed as 1-year survival with 95% confidence intervals in parentheses. RESULTS: The 1-year survival for all 317 patients was 0.86 (0.82-0.90). The patient survival for the group without a left ventricular assist device before cardiac transplant was 0.87 (0.83-0.90), and the survival for the group with a left ventricular assist device as bridge to transplantation was 0.83 (0.67-0.98; P = .77). For the deaths that occurred in all 317 patients, 19% of the patients without left ventricular assist devices died within 30 days of transplant, whereas 80% of the patients with left ventricular assist devices died within 30 days of transplant (P < .01). CONCLUSION: When used as a bridge to transplantation, left ventricular assist devices do not compromise 1-year survival after cardiac transplantation. Of the patients who die after transplantation, patients bridged with left ventricular assist devices are at higher risk for death within 30 days of transplant. These data suggest that left ventricular assist devices as a bridge to transplantation should be considered for appropriately selected patients awaiting cardiac transplantation.

Quality of life and prognosis in heart failure: results of the Beta-Blocker Evaluation of Survival Trial (BEST).

BACKGROUND: Quality of life (QOL) was a prespecified secondary end point in the Beta-Blocker Evaluation of Survival Trial. The Beta-Blocker Evaluation of Survival Trial used four QOL questionnaires to evaluate patient health status over time in response to treatment with placebo or bucindolol. The goal of the current study was to determine the relationship between the different questionnaires, assess the effect of treatment on health status, and evaluate the association between changes in health status and prognosis. METHODS: The San Diego Heart Failure (SDHF), Minnesota Living with Heart Failure (MLHF), Patient Global Assessment (PGA), and Physician Global Assessment (PhyGA) questionnaires were measured at baseline through 48 months of follow-up. For SDHF and MLHF, changes from baseline were calculated. Spearman correlation was used to assess relationships, and Cox Proportional Hazards regression was used to predict time to all-cause mortality, and mortality or heart failure hospitalization, bivariately and multivariately. To determine whether beta-blocker treatment affected QOL, the Wilcoxon rank-sum test was used to compare treatment groups. RESULTS: At 12 months, SDHF (r = +0.56, P = .0001), PGA (r = +0.36, P = .0001), and PhyGA (r = +0.37, P = .0001) correlated with MLHF. SDHF (P = .0001), MLHF (P = .0004), PGA (P = .0001), and PhyGA (P = .0001) were all strongly associated with all-cause mortality, with low values of each associated with a lower hazard. For the combined end point of all-cause mortality or heart failure hospitalization, change in QOL with each instrument had a P value of .0001. At 12 months, bucindolol-treated patients had improvement in both PhyGA and PGA compared with placebo; neither the SDHF nor the MLWF instrument distinguished between the two treatment groups unless a worst-rank assignment was used for patients who died. CONCLUSION: The four instruments correlate with each other and predict clinical end points, suggesting that each is a valid measure of health status. According to the PGA and the PhyGA, bucindolol improves QOL.

Low-dose oral enoximone enhances the ability to wean patients with ultra-advanced heart failure from intravenous inotropic support: results of the oral enoximone in intravenous inotrope-dependent subjects trial.

BACKGROUND: We determined whether low-dose oral enoximone could wean patients with ultra-advanced heart failure (UA-HF) from intravenous (i.v.) inotropic support. Chronic parenteral inotropic therapy in UA-HF is costly and requires an indwelling catheter. An effective and safe oral inotrope would have value. METHODS: In this placebo-controlled study, 201 subjects with UA-HF requiring i.v. inotropic therapy were randomized to enoximone or placebo. Subjects receiving intermittent i.v. inotropes were administered study medication of 25 or 50 mg 3 times a day (tid). Subjects receiving continuous i.v. inotropes were administered 50 or 75 mg tid for 1 week, which was reduced to 25 or 50 mg tid. The ability of subjects to remain alive and free of inotropic therapy was assessed for up to 182 days. RESULTS: Thirty days after weaning, 51 (51%) subjects on placebo and 62 (61.4%) subjects in the enoximone group were alive and free of i.v. inotropic therapy (unadjusted primary end point P = 0.14, adjusted for etiology P = .17). At 60 days, the wean rate was 30% in the placebo group and 46.5% in the enoximone group (unadjusted P = .016) Kaplan-Meier curves demonstrated a trend toward a decrease in the time to death or reinitiation of i.v. inotropic therapy over the 182-day study period (hazard ratio 0.76 [95% CI 0.55-1.04]) and a reduction at 60 days (0.62 [95% CI 0.43-0.89], P = .009) and 90 days (0.69 [95% CI 0.49-0.97], P = .031) after weaning in the enoximone group. CONCLUSIONS: Although there was no benefit over placebo in weaning patients from i.v. inotropes from 0 to 30 days, the EMOTE data suggest that low-dose oral enoximone can be used to wean a modest percentage of subjects from i.v. inotropic support for up to 90 days after initiation of therapy.

Serial gene expression profiling in the intact human heart.

BACKGROUND: In chronic heart failure due to a dilated cardiomyopathy phenotype, the molecular bases for contractile dysfunction and chamber remodeling remain largely unidentified. METHODS: To investigate the feasibility of measuring global gene expression serially in the intact failing human heart, we performed repeated messenger RNA (mRNA) expression profiling using RNA extracted from endomyocardial biopsy specimens and gene chip methodology in 8 subjects with idiopathic dilated cardiomyopathy. In patients treated with beta-blocking agents or placebo, myocardial gene expression was measured in endomyocardial biopsy material and radionuclide ejection fraction was measured at baseline and after 4 to 12 months of treatment. Gene expression was measured for 12,625 gene sequences by using Affymetrix U95 gene chips and commercially available software. For 6 mRNAs, gene chip results were compared with measurements made by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: In an unfiltered composite analysis of changes in expression detected in the patients with high-signal intensity chips, 241 genes showed an increase and 331 genes a decrease in mRNA abundance. There was good agreement between changes measured by quantitative RT-PCR and those determined by gene chips. There was less variance between differences in phenotype in patients sampled serially as compared between subjects with similar phenotypes sampled at baseline. CONCLUSIONS: Serial gene expression profiling with association to phenotypic change is feasible in the intact human heart and may offer advantages to cross-sectional expression profiling. This study suggests that the intact failing remodeled human heart is in an activated state of gene expression, with a large net reduction in gene expression occurring as phenotypic improvement occurs.

Importance of right ventricular end-systolic regional wall stress in idiopathic pulmonary arterial hypertension: a new method for estimation of right ventricular wall stress.

RV dysfunction in idiopathic (primary) pulmonary hypertension (IPAH) is often characterized by chamber dilation, ventricular hypertrophy, and impaired systolic function. In this study we characterize right ventricular (RV) chamber size, end-diastolic thickness, myocardial mass, and ejection fraction in patients with right ventricular heart failure from IPAH, n = 16 and compare these characteristics to a control population of cardiac transplant patients (TX, n = 4) and a group of normal subjects (N, n = 5). Subjects underwent both gated cardiac magnetic resonance imaging (MRI) of the right ventricle and right heart catheterization (RHC). Using parameters from both the MRI and RHC, an estimate of RV end-systolic relative wall stress (RWS) was calculated. RV RWS was 34.7 +/- 8.4 and 17.3 +/- 3.8 Kdynes/cm2 in the cardiac transplant and control subjects respectively and was significantly elevated 104.1 Kdynes/cm2 in IPAH patients (IPAH vs N and TX; p = 0.004 and 0.008 ). RV ejection fraction RVEF was lower in IPAH patients 0.36 +/- .10 than in N and TX 0.57 +/- .04 and 0.55 +/- .08 respectively, (p = 0.0006 N and 0.0007 TX). An inverse linear correlation was demonstrated between RWS and RVEF (y = 215- 332x; R = .80, p < or = .0001). Right ventricular RWS is significantly elevated in IPAH and may provide a useful quantitative monitoring tool in patients with IPAH to assess the benefit of different therapeutic interventions and provide prognostic information.

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.

Peak oxygen consumption and outcome in heart failure patients chronically treated with beta-blockers.

BACKGROUND: Peak oxygen consumption (VO(2)) is an important criterion for listing patients for cardiac transplantation. Beta-blockers improve survival without affecting peak VO(2). We questioned the value of peak VO(2) in predicting outcome in patients treated with beta-blockers. METHODS AND RESULTS: We reviewed the records of 127 patients who had peak VO(2) measured at baseline and were subsequently treated with beta-blockers for at least 3 months. We divided the patients into 2 groups with peak oxygen consumption >14 (VO(2) hi) and < or =14 ml.kg.min (VO(2) lo). VO(2) hi had 109 patients and VO(2) lo had 18 patients. The combined end-point of death or cardiac transplantation was compared between groups. Mean peak VO(2) and left ventricular ejection fraction were lower in VO(2) lo versus VO(2) hi: 12.4+/-1.4 ml.kg.min versus 19.1+/-3.9 ml.kg.min and 17+/-8% versus 21+/-9%, respectively. At 30 months, the percentage of patients who did not reach the combined end-point was 94% in VO(2) lo versus 79% in VO(2) hi (P=.47). In multivariate analysis, only changes in heart rate and LVEF from baseline to follow-up were predictive of survival. CONCLUSIONS: Current peak VO(2) cutoff does not predict survival without transplantation of patients who tolerate chronic treatment with beta-blockers.

Dose-related effects of methadone on QT prolongation in a series of patients with torsade de pointes.

STUDY OBJECTIVE: To investigate the relationship between the daily dose of the synthetic opioid methadone and the corrected QT (QTc) interval in a series of methadone-treated patients who developed torsade de pointes. DESIGN: Retrospective case series analysis. SETTING: Outpatient pain management center and methadone maintenance treatment programs. PATIENTS: Seventeen patients who developed torsade de pointes while receiving very high daily doses of methadone. MEASUREMENTS AND MAIN RESULTS: The QTc intervals were calculated for each patient. The relationship between daily methadone dose and QTc interval was assessed and adjusted for clinical characteristics that may have independently prolonged cardiac repolarization. The mean QTc interval was 615 +/- 77 msec. Multiple linear regression indicated that only the daily methadone dose was predictive of the QTc interval (r = +0.51, p = 0.03). All other variables examined, such as age, sex, presence of hypokalemia or structural heart disease, and presence of QT-prolonging drugs, were not predictive of the QTc interval (minimum p = 0.28). CONCLUSION: In this series, the daily methadone dose correlated positively with the QTc interval. This finding supports the possibility that methadone contributed to the development of arrhythmia.

Angiotensin-converting enzyme DD genotype in patients with primary pulmonary hypertension: increased frequency and association with preserved haemodynamics.

UNLABELLED: HYPOTHESIS/INTRODUCTION: A polymorphic marker within the angiotensin- converting enzyme (ACE) gene has been associated with circulating and tissue ACE activity and with a variety of forms of cardiovascular disease. Since angiotensin II (Ang II) causes pulmonary vasoconstriction and vascular and myocardial remodelling, we postulated a role for the renin-angiotensin system and the ACE DD genotype in the pathophysiology of primary pulmonary hypertension (PPH) and in the right ventricular response to pressure overload in these patients. METHODS AND RESULTS: The incidence of the ACE DD genotype was evaluated in 60 patients with severe PPH compared with two normal control populations, a group of healthy population-based controls (n=158) and subjects found suitable for cardiac organ donation (n=79). Genomic DNA extracted from peripheral leukocytes was amplified using the polymerase chain reaction to detect polymorphic markers. Haemodynamics were determined by right heart catheterisation in a subset of the PPH patients. The frequency of the ACE DD genotype was 45% in the patients with PPH, compared with 24% in the organ donors, and 28% in population-based healthy controls (p=0.01 for chi-square test). Of the 32 PPH patients with baseline haemodynamics, 12 exhibited the ACE DD genotype and 20 were non-DD. While the mean pulmonary artery pressure and the duration of symptoms attributable to pulmonary hypertension was not different between the DD and non-DD groups, cardiac output was significantly lower (3.29+0.27 vs. 5.07+0.37 L/minute, p=0.002) and the mean right atrial pressure tended to be higher (8.85+1.29 vs. 4.92+1.27 mmHg, p=0.08) in the non-DD group. The reduction in cardiac output seen in the non-DD group was not due to a difference in heart rate, but to a significant reduction in stroke volume, consistent with a decreased contractile state. In addition, non-DD patients exhibited a significantly worse functional capacity (NYHA Class 3.14+0.12 vs. 2.40+0.28, p=0.02). CONCLUSIONS: 1) The ACE DD genotype is significantly increased in patients with severe PPH compared with normal controls, suggesting that certain individuals may be genetically predisposed to developing pulmonary hypertension. 2) The ACE DD genotype is associated with preserved right ventricular function in PPH patients, supporting a compensatory myocardial or inotropic role for Ang II in the pressure overloaded right ventricle.

Natural history of dilated cardiomyopathy due to lamin A/C gene mutations.

OBJECTIVES: We examined the prevalence, genotype-phenotype correlation, and natural history of lamin A/C gene (LMNA) mutations in subjects with dilated cardiomyopathy (DCM). BACKGROUND: Mutations in LMNA have been found in patients with DCM with familial conduction defects and muscular dystrophy, but the clinical spectrum, prognosis, and clinical relevance of laminopathies in DCM are unknown. BACKGROUND: A cohort of 49 nuclear families, 40 with familial DCM and 9 with sporadic DCM (269 subjects, 105 affected), was screened for mutations in LMNA using denaturing high-performance liquid chromatography and sequence analysis. Bivariate analysis of clinical predictors of LMNA mutation carrier status and Kaplan-Meier survival analysis were performed. RESULTS: Mutations in LMNA were detected in four families (8%), three with familial (R89L, 959delT, R377H) and one with sporadic DCM (S573L). There was significant phenotypic variability, but the presence of skeletal muscle involvement (p < 0.001), supraventricular arrhythmia (p = 0.003), conduction defects (p = 0.01), and "mildly" DCM (p = 0.006) were predictors of LMNA mutations. The LMNA mutation carriers had a significantly poorer cumulative survival compared with non-carrier DCM patients: event-free survival at the age of 45 years was 31% versus 75% in non-carriers. CONCLUSIONS: Mutations in LMNA cause a severe and progressive DCM in a relevant proportion of patients. Mutation screening should be considered in patients with DCM, in particular when clinical predictors of LMNA mutation are present, regardless of family history.

Hypoplastic left heart syndrome myocytes are differentiated but possess a unique phenotype.

INTRODUCTION: Hypoplastic left heart syndrome (HLHS) is the term used to describe a group of congenital malformations characterized by marked underdevelopment of the left side of the heart. HLHS accounts for nearly 25% of cardiac deaths in the first year of life. Although much has been reported regarding diagnosis, gross morphology and surgical treatment, no information on gene expression in HLHS myocytes is available. METHODS: We examined heart tissue from patients with HLHS using routine histology, immunohistochemistry, quantitative polymerase chain reaction (PCR), two-dimensional (2-D) gel electrophoresis and protein identification by mass spectrometry. RESULTS: Histologic examination of right and left ventricles from HLHS patients revealed characteristic features of myocyte differentiation, including striations and intercalated disc formation. Immunohistochemical staining using antibody to N-cadherin demonstrated clear development of intercalated discs between myocytes. However, many of the myocytes contained scant cytoplasm and were grouped in small, disorganized bundles separated by abundant connective tissue and dilated, thin-walled vessels. Quantitative PCR analysis demonstrated that both left and right ventricular tissue from HLHS hearts expressed the fetal or "heart failure" gene expression pattern. Two-dimensional gel electrophoresis and protein identification by mass spectrometry also confirmed that myocytes from HLHS ventricles were differentiated but expressed the fetal isoform of some cardiac specific proteins. However, HLHS myocytes in all of the heart samples (n=21) were inappropriately expressing platelet-endothelial cell adhesion molecule-1 (PECAM-1, CD31), a member of the cell adhesion molecule (CAM) family that has a primary role in the regulation of tissue morphogenesis. These findings indicate that myocytes from HLHS syndrome patients, while differentiated, have a unique gene expression pattern.

The origin of electrochemical activity in Li2MnO3.

The electrochemical activity of Li2MnO3 in non-aqueous media has been investigated and found to involve neither Mn(4+)-Mn5+ oxidation nor simultaneous O2- removal but exchange of Li+ by H+, the latter being generated in the electrolyte.

Beta-blocker therapy influences the hemodynamic response to inotropic agents in patients with heart failure: a randomized comparison of dobutamine and enoximone before and after chronic treatment with metoprolol or carvedilol.

OBJECTIVE: We compared the hemodynamic effects of dobutamine and enoximone administration before and after long-term beta-blocker therapy with metoprolol or carvedilol in patients with chronic heart failure (HF). BACKGROUND: Patients with HF on beta-blocker therapy may need hemodynamic support with inotropic agents, and the hemodynamic response may be influenced by both the inotropic agent and the beta-blocker used. METHODS: The hemodynamic effects of dobutamine (5 to 20 microg/kg/min intravenously) and enoximone (0.5 to 2 mg/kg intravenously) were assessed by pulmonary artery catheterization in 29 patients with chronic HF before and after 9 to 12 months of treatment with metoprolol or carvedilol at standard target maintenance oral doses. Hemodynamic studies were performed after >/=12 h of wash-out from all cardiovascular medications, except the beta-blockers that were administered 3 h before the second study. RESULTS: Compared with before beta-blocker therapy, metoprolol treatment decreased the magnitude of mean pulmonary artery pressure (PAP) and pulmonary wedge pressure (PWP) decline during dobutamine infusion and increased the cardiac index (CI) and stroke volume index (SVI) response to enoximone administration, without any effect on other hemodynamic parameters. Carvedilol treatment abolished the increase in heart rate, SVI, and CI and caused a rise, rather than a decline, in PAP, PWP, systemic vascular resistance, and pulmonary vascular resistance during dobutamine infusion. The hemodynamic response to enoximone, however, was maintained or enhanced in the presence of carvedilol. CONCLUSIONS: In contrast with its effects on enoximone, carvedilol and, to a lesser extent, metoprolol treatment may significantly inhibit the favorable hemodynamic response to dobutamine. No such beta-blocker-related attenuation of hemodynamic effects occurs with enoximone.

Torsade de pointes associated with very-high-dose methadone.

BACKGROUND: Methadone is an effective treatment for opioid dependency and chronic pain. A methadone derivative, levacetylmethadol, was withdrawn from the European market after being associated with torsade de pointes. To date, no association between methadone and this arrhythmia has been described. OBJECTIVE: To evaluate a series of methadone-treated patients experiencing torsade de pointes. DESIGN: Retrospective case series. SETTING: Methadone maintenance treatment programs in the United States and a pain management center in Canada. PATIENTS: 17 methadone-treated patients who developed torsade de pointes. MEASUREMENTS: Chart review for concomitant arrhythmia risk factors and quantification of corrected QT interval (QTc). RESULTS: The mean daily methadone dose was 397 +/- 283 mg, and the mean QTc interval was 615 +/- 77 msec. Fourteen patients had a predisposing risk factor for arrhythmia. A cardiac defibrillator or pacemaker was placed in 14 patients; all 17 patients survived. CONCLUSIONS: This series raises concern that very-high-dose methadone may be associated with torsade de pointes. Given the likely expansion of methadone treatment into primary care, further investigation of these findings is warranted.

Myocardial gene expression in dilated cardiomyopathy treated with beta-blocking agents.

BACKGROUND: Beta-blocker therapy may improve cardiac function in patients with idiopathic dilated cardiomyopathy. We tested the hypothesis that beta-blocker therapy produces favorable functional effects in dilated cardiomyopathy by altering the expression of myocardial genes that regulate contractility and pathologic hypertrophy. METHODS: We randomly assigned 53 patients with idiopathic dilated cardiomyopathy to treatment with a beta-adrenergic-receptor blocking agent (metoprolol or carvedilol) or placebo. The amount of messenger RNA (mRNA) for contractility-regulating genes (those encoding beta1- and beta2-adrenergic receptors, calcium ATPase in the sarcoplasmic reticulum, and alpha- and beta-myosin heavy-chain isoforms) and of genes associated with pathologic hypertrophy (beta-myosin heavy chain and atrial natriuretic peptide) was measured with a quantitative reverse-transcription polymerase chain reaction in total RNA extracted from biopsy specimens of the right ventricular septal endomyocardium. Myocardial levels of beta-adrenergic receptors were also measured. Measurements were conducted at base line and after six months of treatment, and changes in gene expression were compared with changes in the left ventricular ejection fraction as measured by radionuclide ventriculography. RESULTS: Twenty-six of 32 beta-blocker-treated patients (those with complete mRNA measurements) had an improvement in left ventricular ejection fraction of at least 5 ejection-fraction (EF) units (mean [+/-SE] increase, 18.8+/-1.8). As compared with the six beta-blocker-treated patients who did not have a response (mean change, a decrease of 2.5+/-1.8 EF units), those who did have a response had an increase in sarcoplasmic-reticulum calcium ATPase mRNA and alpha-myosin heavy chain mRNA and a decrease in beta-myosin heavy chain mRNA. The change in sarcoplasmic-reticulum calcium ATPase was not present in the patients in the placebo group who had a spontaneous response. There were no differences between those who had a response and those who did not in terms of the change in mRNA or protein expression of beta-adrenergic receptors. CONCLUSIONS: In idiopathic dilated cardiomyopathy, functional improvement related to treatment with beta-blockers is associated with changes in myocardial gene expression.