Targeting Sympathetic Overactivity in Heart Failure Patients With Statins

Study Overview
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Brief Summary
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Heart failure (HF) is a leading cause of morbidity and mortality in the United States with the incidence and prevalence of the disease on a continual rise. An overactive sympathetic nervous system has become a hallmark characteristic of HF. Although sympathetic activation is initially beneficial to maintain cardiac output, blood pressure and perfusion to vital organs, over the long term it becomes deleterious contributing to the worsening of HF and sudden cardiac death. Indeed, recent findings in HF patients suggest that the sympathetic overactivity is not just a marker of poor prognosis but it plays a causative role in the development of the disease. Thus, the sympathetic nervous system constitutes a putative drug target in the treatment of HF. However, despite aggressive medical management, including conventional anti-adrenergic strategies, sympathetic nerve activity (SNA) has been shown to remain abnormally high in HF patients and improvements in survival have been limited. Thus, other treatment strategies that include reducing SNA and its deleterious consequences are warranted. Recent findings from clinical trials indicate that 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitors (statins) improve survival irrespective of cholesterol lowering bringing the pleiotropic (i.e., cholesterol independent) effects of statins to the forefront. An important pleiotropic effect recently reported in experimental HF, that has yet to be directly tested in human HF, is the ability of statins to reduce resting sympathetic outflow. Several studies in pacing-induced HF rabbits have demonstrated that statins normalize the excessive sympathetic activation in the HF state. Thus, the goal of this project is to determine whether these findings in experimental HF can be translated to the clinical setting of human HF. Our central hypothesis is that statins reduce sympathetic overactivity in HF patients. To test this hypothesis we will directly measure muscle SNA and perform a randomized crossover placebo control study. Subjects will come to the research laboratory before and after the administration of Simvastatin at a standard therapeutic dosage of 40 mg. per day or placebo for 1 month

Detailed Description
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Heart failure (HF) is a leading cause of morbidity and mortality in the United States with the incidence and prevalence of the disease on a continual rise. An overactive sympathetic nervous system has become a hallmark characteristic of HF. Although sympathetic activation is initially beneficial to maintain cardiac output, blood pressure and perfusion to vital organs, over the long term it becomes deleterious contributing to the worsening of HF and sudden cardiac death. Indeed, recent findings in HF patients suggest that the sympathetic overactivity is not just a marker of poor prognosis but it plays a causative role in the development of the disease. Thus, the sympathetic nervous system constitutes a putative drug target in the treatment of HF. However, despite aggressive medical management, including conventional anti-adrenergic strategies, sympathetic nerve activity (SNA) has been shown to remain abnormally high in HF patients and improvements in survival have been limited. Thus, other treatment strategies that include reducing SNA and its deleterious consequences are warranted. Recent findings from clinical trials indicate that 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitors (statins) improve survival irrespective of cholesterol lowering bringing the pleiotropic (i.e., cholesterol independent) effects of statins to the forefront. An important pleiotropic effect recently reported in experimental HF, that has yet to be directly tested in human HF, is the ability of statins to reduce resting sympathetic outflow. Several studies in pacing-induced HF rabbits have demonstrated that statins normalize the excessive sympathetic activation in the HF state. Thus, the goal of this proposal is to determine whether these findings in experimental HF can be translated to the clinical setting of human HF. Our central hypothesis is that statins reduce sympathetic overactivity in HF patients. To test this hypothesis we will directly measure muscle SNA before and after one month of statin therapy. In addition, to begin to elucidate the potential mechanism(s) involved in statin-induced reductions in SNA we will use the technique of partial autospectral analysis to assess the baroreflex-independent (i.e., central) component of SNA and the application of neck pressure and neck suction to assess the baroreflex-dependent control of SNA. The significance of the proposed experiments is the potential of statin therapy to reduce SNA in HF patients providing a novel therapeutic strategy to target the heightened resting sympathetic drive present in HF. The study will utilize a randomized crossover placebo-controlled study design. Subjects will come to the research laboratory before, during and after the administration of either a placebo or Simvastatin for one month at a standard therapeutic dosage of 40 mg per day. Subjects will be carefully monitored for any adverse effects by examining blood samples at baseline and 4 weeks for markers of liver, kidney, or muscle damage. If the subject's responses to one month of Simvastatin therapy are minimal, such that the decrease in LDL cholesterol is less than 25%, we will ask them to participate in an additional 2 weeks of Simvastatin administration at a dosage of 80 mg per day. During the baseline, the visit at 4 wks, and during the additional visit (if necessary) subjects will undergo the following experimental measurements and procedures, which will take approximately four hours. All measurements and procedures will be performed by the principal investigator and trained research personnel. To completely obtain all the data necessary for this project, it would be expected to take 5 years. This is based on the goal of initially collecting additional data to add to the preliminary data of a recent American Heart Association (AHA) grant submission and then submitting the project for an NIH grant. Based on power calculations and previous experience using these experimental measures, it will take approximately 30 heart failure patients to determine the influence of statins on sympathetic nerve activity. This will permit statistical comparisons and takes into account the technical difficulties of obtaining repeat quality sympathetic nerve recordings in the same patient as well as the data collection necessary to determine the potential contribution of baroreflex-dependent and -independent mechanisms. Healthy control subjects matched to each HF patients for age, sex, and body mass index, all of which are known factors that influence resting SNA, will also be studied. These studies are important for comparison to determine whether these statin-induced reductions in SNA specific to HF or a general overall effect of statin therapy. It is anticipated that identifying patients not already on statin therapy may take some time as this therapy is standard in this patients group. We chose Simvastatin for our studies because this was the statin of choice in the pacing-induced HF rabbit studies that have reported a normalization of resting SNA after statin therapy. We anticipate that future studies identifying the efficacy of different statins in reducing SNA, the impact of different dosages, and different durations of treatment will be warranted.

Official Title
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Targeting Sympathetic Overactivity in Heart Failure Patients With Statins

Conditions
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Heart Failure

Intervention / Treatment
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* Drug: Simvastatin
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male and females of all ethnic backgrounds ranging aged 18 to 70 Ages 18-70 yrs Patients with congestive heart failure diagnosed on clinical history, a routine exercise test, echocardiography and/or routine cardiac catheterization, in functional class I-III Patients with heart failure due to ischemic and non-ischemic etiologies Normotensive and not taking blood pressure controlling medications Exclusion Criteria: Low blood pressure (<100/60) End stage renal disease Chronic Obstructive Pulmonary Disease (COPD) with concurrent daily use of inhalers Peripheral neuropathy Pregnant women

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Simvastatin<br>40 mg Simvastatin 1 pill every day for 30 days | Drug: Simvastatin<br>* 40 mg, P.O.,daily for 30 days<br>* Other names: Zocor;|
| Placebo Comparator: Placebo<br>Placebo cap 1 pill every day for 30 days | Drug: Placebo<br>* 1 capsule daily for 30 days<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Muscle Sympathetic Nerve Activity in Bursts Per 100 Heartbeats | Muscle sympathetic nerve activity will be assessed after one month of placebo and statin therapy; measured in bursts/100 heartbeats. | Baseline and 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Measures of Reactive Oxygen Species in the Blood | Reactive Oxygen Species will be assessed after one month of placebo and statin therapy; measured using electron parametric resonance spectroscopy (EPR). | Baseline and 30 days |