Disconnect between the effects of serelaxin on renal function and outcome in acute heart failure.

BACKGROUND: We aimed to study whether improvement in renal function by serelaxin in patients who were hospitalized for acute heart failure (HF) might explain any potential effect on clinical outcomes. METHODS: We included 6318 patients from the RELAXin in AHF-2 (RELAX-AHF2) study. Improvement in renal function was defined as a decrease in serum creatinine of ≥ 0.3 mg/dL and ≥ 25%, or increase in estimated glomerular filtration rate of ≥ 25% between baseline and day 2. Worsening renal function (WRF) was defined as the reverse. We performed causal mediation analyses regarding 180-day all-cause mortality (ACM), cardiovascular death (CVD), and hospitalization for HF/renal failure. RESULTS: Improvement in renal function was more frequently observed with serelaxin when compared with placebo [OR 1.88 (95% CI 1.64-2.15, p < 0.0001)], but was not associated with subsequent clinical outcomes. WRF occurred less frequent with serelaxin [OR 0.70 (95% CI 0.60-0.83, p < 0.0001)] and was associated with increased risk of ACM, worsening HF and the composite of CVD and HF or renal failure hospitalization. Improvement in renal function did not mediate the treatment effect of serelaxin [CVD HR 1.01 (0.99-1.04), ACM HR 1.01 (0.99-1.03), HF/renal failure hospitalization HR 0.99 (0.97-1.00)]. CONCLUSIONS: Despite the significant improvement in renal function by serelaxin in patients with acute HF, the potential beneficial treatment effect was not mediated by improvement in renal function. These data suggest that improvement in renal function might not be a suitable surrogate marker for potential treatment efficacy in future studies with novel relaxin agents in acute HF. Central illustration. Conceptual model explaining mediation analysis; treatment efficacy of heart failure therapies mediated by renal function.

Prevalence of AAV1 neutralizing antibodies and consequences for a clinical trial of gene transfer for advanced heart failure.

Adeno-associated virus serotype 1 (AAV1) has many advantages as a gene therapy vector, but the presence of pre-existing neutralizing antibodies (NAbs) is an important limitation. This study was designed to determine: (1) characteristics of AAV NAbs in human subjects, (2) prevalence of AAV1 NAbs in heart failure patients and (3) utility of aggressive immunosuppressive therapy in reducing NAb seroconversion in an animal model. NAb titers were assessed in a cohort of heart failure patients and in patients screened for a clinical trial of gene therapy with AAV1 carrying the sarcoplasmic reticulum calcium ATPase gene (AAV1/SERCA2a). AAV1 NAbs were found in 59.5% of 1552 heart failure patients. NAb prevalence increased with age (P=0.001) and varied geographically. The pattern of NAb titers suggested that exposure is against AAV2, with AAV1 NAb seropositivity due to crossreactivity. The effects of immunosuppression on NAb formation were tested in mini-pigs treated with immunosuppressant therapy before, during and after a single AAV1/SERCA2a infusion. Aggressive immunosuppression did not prevent formation of AAV1 NAbs. We conclude that immunosuppression is unlikely to be a viable solution for repeat AAV1 dosing. Strategies to reduce NAbs in heart failure patients are needed to increase eligibility for gene transfer using AAV vectors.

Effect of nesiritide in patients with acute decompensated heart failure.

BACKGROUND: Nesiritide is approved in the United States for early relief of dyspnea in patients with acute heart failure. Previous meta-analyses have raised questions regarding renal toxicity and the mortality associated with this agent. METHODS: We randomly assigned 7141 patients who were hospitalized with acute heart failure to receive either nesiritide or placebo for 24 to 168 hours in addition to standard care. Coprimary end points were the change in dyspnea at 6 and 24 hours, as measured on a 7-point Likert scale, and the composite end point of rehospitalization for heart failure or death within 30 days. RESULTS: Patients randomly assigned to nesiritide, as compared with those assigned to placebo, more frequently reported markedly or moderately improved dyspnea at 6 hours (44.5% vs. 42.1%, P=0.03) and 24 hours (68.2% vs. 66.1%, P=0.007), but the prespecified level for significance (P≤0.005 for both assessments or P≤0.0025 for either) was not met. The rate of rehospitalization for heart failure or death from any cause within 30 days was 9.4% in the nesiritide group versus 10.1% in the placebo group (absolute difference, -0.7 percentage points; 95% confidence interval [CI], -2.1 to 0.7; P=0.31). There were no significant differences in rates of death from any cause at 30 days (3.6% with nesiritide vs. 4.0% with placebo; absolute difference, -0.4 percentage points; 95% CI, -1.3 to 0.5) or rates of worsening renal function, defined by more than a 25% decrease in the estimated glomerular filtration rate (31.4% vs. 29.5%; odds ratio, 1.09; 95% CI, 0.98 to 1.21; P=0.11). CONCLUSIONS: Nesiritide was not associated with an increase or a decrease in the rate of death and rehospitalization and had a small, nonsignificant effect on dyspnea when used in combination with other therapies. It was not associated with a worsening of renal function, but it was associated with an increase in rates of hypotension. On the basis of these results, nesiritide cannot be recommended for routine use in the broad population of patients with acute heart failure. (Funded by Scios; ClinicalTrials.gov number, NCT00475852.).

Inotropic therapy for heart failure: an evidence-based approach.

BACKGROUND: Agents that increase cardiac contractility (positive inotropes) have beneficial hemodynamic effects in patients with acute and chronic heart failure but have frequently led to increased mortality when given on a long-term basis. Despite this fact, inotropes remain commonly used in the management of heart failure. METHODS: We reviewed the available data on short- and long-term inotrope use in heart failure, emphasizing high-quality evidence on the basis of randomized trials that were powered to address clinical end points. RESULTS: Available data suggest that long-term inotropic therapy has a negative impact on survival in patients with heart failure, regardless of the agent used. The data that inotropic therapy improves quality of life are mixed. High-quality randomized evidence is lacking for the use of inotropes for other heart failure indications, such as for acute decompensations or as a "bridge to transplant." CONCLUSIONS: On the basis of the available evidence, the routine use of inotropes as heart failure therapy is not indicated in either the acute or chronic setting. Potentially appropriate uses of inotropes include as temporary treatment of diuretic-refractory acute heart failure decompensations or as a bridge to definitive treatment such as revascularization or cardiac transplantation. Inotropes also may be appropriate as a palliative measure in patients with truly end-stage heart failure. A model of heart failure pathophysiologic features that combines an understanding of both hemodynamic and neurohormonal factors will be required to best develop and evaluate novel treatments for advanced heart failure.

Rational use of inotropic therapy in heart failure.

Despite their theoretic appeal, agents that increase cardiac contractility (positive inotropes) have consistently been shown to increase mortality when given chronically to patients with heart failure. The routine use of inotropes as heart failure therapy in either the acute or the chronic setting is not supported by the available data. Some appropriate uses of inotropes are as temporary treatment of diuretic-refractory acute heart failure decompensations, or as a bridge to definitive treatment such as revascularization or cardiac transplantation. Although controversial, the use of inotropes as a palliative measure in the small subset of patients with truly end-stage heart failure may be appropriate. An understanding of the appropriate goals of therapy is important for both patients and physicians if rational decisions about the use of inotropes are to be made.

Myocarditis and long-term survival in peripartum cardiomyopathy.

BACKGROUND: The reported mortality rate of peripartum cardiomyopathy (PPCM) is high, although the potential for spontaneous recovery of ventricular function is well established. The prevalence of myocarditis in PPCM has varied widely between studies. The purposes of this study were to define the long-term prognosis in a referral population of patients with PPCM, to determine the prevalence of myocarditis on endomyocardial biopsy in this population, and to identify clinical variables associated with poor outcome. METHODS: We analyzed clinical, echocardiographic, hemodynamic, and histologic features of 42 women with PPCM evaluated at our institution over a 15-year period. Each patient underwent an extensive evaluation, including echocardiography, endomyocardial biopsy, and right heart catheterization. Data were analyzed to identify features at initial examination associated with the combined end point of death or cardiac transplantation by the use of Kaplan-Meier survival curves and a Cox proportional hazards model. RESULTS: Three (7%) patients died and 3 (7%) patients underwent heart transplantation during a median follow-up of 8.6 years. Endomyocardial biopsy demonstrated a high prevalence of myocarditis (62%), but the presence or absence of myocarditis was not associated with survival. Of the prespecified variables assessed, only decreased left ventricular stroke work index was associated with worsened outcome. CONCLUSIONS: In patients with PPCM, (1) long-term survival is better than has been historically reported, (2) the prevalence of myocarditis is high, and (3) decreased left ventricular stroke work index is associated with worse clinical outcomes.

Echocardiographic findings in fulminant and acute myocarditis.

OBJECTIVES: We sought to use echocardiography to assess the presentation and potential for recovery of left ventricular (LV) function of patients with fulminant myocarditis compared with those with acute myocarditis. BACKGROUND: The clinical course of patients with myocarditis remains poorly defined. We have previously proposed a classification that provides prognostic information in myocarditis patients. Fulminant myocarditis causes a distinct onset of illness and severe hemodynamic compromise, whereas acute myocarditis has an indistinct presentation, less severe hemodynamic compromise and a greater likelihood of progression to dilated cardiomyopathy. METHODS: Echocardiography was performed at presentation and at six months to test the hypothesis that fulminant (n = 11) or acute (n = 43) myocarditis could be distinguished morphologically. RESULTS: Patients with both fulminant (fractional shortening 19 +/- 4%) and acute myocarditis (17 +/- 7%) had LV systolic dysfunction. Patients with fulminant myocarditis had near normal LV diastolic dimensions (5.3 +/- 0.9 cm) but increased septal thickness (1.2 +/- 0.2 cm) at presentation, while those with acute myocarditis had increased diastolic dimensions (6.1 +/- 0.8 cm, p < 0.01 vs. fulminant) but normal septal thickness (1.0 +/- 0.1 cm, p = 0.01 vs. fulminant). At six months, patients with fulminant myocarditis had dramatic improvement in fractional shortening (30 +/- 8%) compared with no improvement in patients with acute myocarditis (19 +/- 7%, p < 0.01 for interaction between time and type of myocarditis). CONCLUSIONS: Fulminant myocarditis is distinguishable from acute myocarditis by echocardiography. Patients with fulminant myocarditis exhibit a substantial improvement in ventricular function at six months compared with those with acute myocarditis. Echocardiography has value in classifying patients with myocarditis and may provide prognostic information.

Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy.

BACKGROUND: Previous studies of the prognosis of patients with heart failure due to cardiomyopathy categorized patients according to whether they had ischemic or nonischemic disease. The prognostic value of identifying more specific underlying causes of cardiomyopathy is unknown. METHODS: We evaluated the outcomes of 1230 patients with cardiomyopathy. The patients were grouped into the following categories according to underlying cause: idiopathic cardiomyopathy (616 patients), peripartum cardiomyopathy (51); and cardiomyopathy due to myocarditis (111), ischemic heart disease (91), infiltrative myocardial disease (59), hypertension (49), human immunodeficiency virus (HIV) infection (45), connective-tissue disease (39), substance abuse (37), therapy with doxorubicin (15), and other causes (117). Cox proportional-hazards analysis was used to assess the association between the underlying cause of cardiomyopathy and survival. RESULTS: During a mean follow-up of 4.4 years, 417 patients died and 57 underwent cardiac transplantation. As compared with the patients with idiopathic cardiomyopathy, the patients with peripartum cardiomyopathy had better survival (adjusted hazard ratio for death, 0.31; 95 percent confidence interval, 0.09 to 0.98), and survival was significantly worse among the patients with cardiomyopathy due to infiltrative myocardial disease (adjusted hazard ratio, 4.40; 95 percent confidence interval, 3.04 to 6.39), HIV infection (adjusted hazard ratio, 5.86; 95 percent confidence interval, 3.92 to 8.77), therapy with doxorubicin (adjusted hazard ratio, 3.46; 95 percent confidence interval, 1.67 to 7.18), and ischemic heart disease (adjusted hazard ratio, 1.52; 95 percent confidence interval, 1.07 to 2.17). CONCLUSIONS: The underlying cause of heart failure has prognostic value in patients with unexplained cardiomyopathy. Patients with peripartum cardiomyopathy appear to have a better prognosis than those with other forms of cardiomyopathy. Patients with cardiomyopathy due to infiltrative myocardial diseases, HIV infection, or doxorubicin therapy have an especially poor prognosis.

The spectrum of dilated cardiomyopathy. The Johns Hopkins experience with 1,278 patients.

This report describes the evaluation of 1,278 patients referred to The Johns Hopkins Hospital with dilated cardiomyopathy. After a careful history and physical examination, selected laboratory tests, and endomyocardial biopsy, a specific diagnosis was made in 49% of cases. In 16% of cases the biopsy demonstrated a specific histologic diagnosis. Myocarditis and coronary artery disease were the most frequent specific diagnoses; 51% of patients were classified as idiopathic. Thus a rigorous and systematic search can demonstrate an underlying cause for approximately one-half of patients with unexplained cardiomyopathy. Endomyocardial biopsy plays a crucial role in this evaluation. Six cases are presented which demonstrate the utility of endomyocardial biopsy in specific clinical situations. In addition to its routine use in monitoring rejection in heart transplant recipients, endomyocardial biopsy is indicated in the evaluation of possible infiltrative cardiomyopathy, in differentiating restrictive cardiomyopathy from constrictive pericarditis, and in diagnosing and monitoring doxorubicin cardiotoxicity. The importance of diagnosing myocarditis remains controversial, and disagreement persists about the utility of immunosuppressive therapy in these patients. A combination of clinical and histologic features can divide patients with myocarditis into 4 subgroups--acute, fulminant, chronic active, and chronic persistent. This classification provides prognostic information and may identify those patients who may respond to immunosuppression, as well as those likely to have adverse outcomes from such treatment. The continued development of novel molecular techniques may allow endomyocardial biopsy to provide greater prognostic and therapeutic information in the future.

Treatment of subcutaneous and intracranial brain tumor xenografts with O6-benzylguanine and 1,3-bis(2-chloroethyl)-1-nitrosourea.

O6-Alkylguanine-DNA alkyltransferase (AT) is a cellular protein that protects cells from the cytotoxic effects of nitrosoureas by repairing alkyl lesions at the O6 position of guanine. We have studied the ability of O6-benzylguanine to deplete AT activity in brain tumor xenografts and thereby increase the sensitivity of these tumors to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). In toxicity studies, pretreatment of athymic mice with O6-benzylguanine increased the toxicity of BCNU significantly. After i.p. injection of O6-benzylguanine into athymic mice carrying subcutaneous (s.c.) D341MED, a human medulloblastoma xenograft with a high AT activity, the AT activity of the tumors became undetectable within 1 h and remained depleted until 36 h. In s.c. xenografts to D341MED, treatment with O6-benzylguanine followed 1 h later by BCNU produced a significantly greater growth delay (14.8 days) than was seen with BCNU alone (2.3 days). A lower pretreatment dose of O6-benzylguanine produced a significantly smaller therapeutic effect. Delaying the administration of BCNU until 36 h after O6-benzylguanine resulted in a growth delay (1.2 days) that was not significantly different from that produced by the control or BCNU alone. In athymic mice with intracranial (i.c.) xenografts of D341MED, pretreatment with O6-benzylguanine followed 1 h later by BCNU produced a significantly increased survival as compared with that of the control, BCNU alone, O6-benzylguanine alone, and O6-benzylguanine followed 36 h later by BCNU. In experiments with s.c. xenografts of D245MG, a human glioma xenograft with undetectable AT activity, pretreatment with O6-benzylguanine 1 h prior to BCNU produced a significantly greater effect than was seen with BCNU treatment alone. The combination regimen, however, was not as effective as an equitoxic dose of BCNU alone. These studies suggest that O6-benzylguanine may be a useful adjuvant to nitrosourea therapy in human malignancies that exhibit a range of AT activities and that dose and timing are important variables in achieving therapeutic success. These data also indicate that therapeutic potentiation of BCNU by O6-benzylguanine can be achieved in i.c. tumors. As a result, this approach may be useful in the treatment of neoplasms of the central nervous system.

Enhancement of nitrosourea activity in medulloblastoma and glioblastoma multiforme.

BACKGROUND: Although chemotherapy offers promise of increased survival for children with medulloblastoma and glioblastoma multiforme, drug resistance occurs frequently, resulting in tumor progression and death. Resistance to nitrosoureas and methylating agents, which damage DNA, can be mediated by a DNA repair protein, O6-alkylguanine-DNA alkyltransferase (AGAT). Depletion of this protein with alkylguanines or methylating agents, however, restores tumor cell sensitivity to the cytotoxicity of chloroethylnitrosoureas (e.g., carmustine [BCNU]). PURPOSE: This study was designed to determine whether resistance to the activity of nitrosourea (the drug BCNU) in BCNU-resistant human medulloblastoma (D341 Med) and human glioblastoma multiforme (D-456 MG) can be reversed by the methylating agent streptozocin and the O6-substituted guanines O6-methylguanine and O6-benzylguanine. METHODS: Xenografts were grown subcutaneously in athymic BALB/c mice. BCNU was administered as a single intraperitoneal injection at doses of 100 mg/m2, 75 mg/m2, or 38 mg/m2--i.e., 1.0, 0.75, or 0.38, respectively, of the dose lethal to 10% of treated animals (LD10). Mice were treated intraperitoneally with a single dose of O6-benzylguanine or O6-methylguanine (240 mg/m2) or with streptozocin (600 mg/m2) daily for 4 days. Response was assessed by tumor growth delay and tumor regression. AGAT activity in the xenografts was measured at 1 and 6 hours after pretreatment, at the time tumors were excised. RESULTS: Pretreatment with O6-benzylguanine, O6-methylguanine, or streptozocin reduced AGAT activity to 4%, 25%, and 95% of control values, respectively, in D341 Med and 0%, 0%, and 25% of control values, respectively, in D-456 MG 1 hour after injection. After 6 hours, levels changed to 7%, 61%, and 116% of control values in D341 Med and 0%, 79%, and 21% of control values in D-456 MG, respectively. Both D341 Med and D-456 MG xenografts were completely resistant to BCNU at its LD10. Pretreatment with O6-benzylguanine increased BCNU sensitivity in both types of xenograft. In contrast, treatment with BCNU plus O6-methylguanine or streptozocin did not produce growth delays substantially different from those produced by BCNU alone, reflecting the more efficient depletion of AGAT by O6-benzylguanine. Following therapy with BCNU plus O6-benzylguanine at 0.38 LD10, tumor regressions were seen in eight of 10 D341 Med and in all 10 D-456 MG xenografts. CONCLUSION: We recommend comprehensive clinical toxicologic evaluation of combination therapy with O6-benzylguanine plus BCNU, which would allow subsequent design of phase I clinical trials.