Study of High Dosage of Losartan in Comparison to Low Dose of Losartan in Heart Failure Patients
Effects of Low-Dose vs High-dose Losartan on Sympathetic Hyperactivity in Patients With Congestive Heart Failure
The sympathetic nervous system, a part of the nervous system that stimulates the heart via release of substances, noradrenaline and adrenaline (combined called catecholamines), becomes activated in people with heart failure. As these people become sicker, the nervous system becomes more active, causing further damage to the heart.
Large trials have shown that Angiotensin-converting enzyme (ACE) inhibitors reduce morbidity and mortality in patients with heart failure. Higher doses of these drugs are more effective than lower doses. Studies show that ACE-inhibitors decrease catecholamine levels. This could be why congestive heart failure (CHF) patients taking this class of drugs show improvement in heart function.
There are several ways of measuring the activity of the sympathetic nervous system. The most common measurement is to test the blood for catecholamine levels. This is not very reliable or reproducible. Microneurography is a new technique used to measure sympathetic nerve activity. A small electrode (comparable to an acupuncture needle) is placed in a muscle nerve and hooked up to a stimulator and a recorder. It produces direct recordings of skeletal muscle nerve traffic. Both the rate and amplitude of the burst can be measured. The results in this technique are highly reproducible. By using this technique we get a more accurate picture of how the nervous system responds to medications given to treat heart failure.
Losartan (Cozaar) is an angiotensin II type 1 (AT1) receptor blocker. It blocks the binding of angiotensin II, a hormone that constricts blood vessels. As a result the blood vessels remain relaxed, leading to a reduction in the workload of the heart. Minor decreases in blood catecholamine levels have been reported with a low dose of this drug. The purpose of this study is to see whether a high dose of losartan (200 mg) has a greater effect on the sympathetic nervous system than a low dose of losartan (50 mg) does.
A total of 30 participants will be recruited. Participants will be assigned to one of two groups: high-dose, in which subjects will receive treatment of 200 mg/day of losartan, and low-dose, in which subjects will receive treatment of 50 mg/day of losartan. Via microneurography the investigators will measure the difference in sympathetic activity in subjects in high-dose vs low-dose losartan. The investigators expect to see further decrease in sympathetic activity in high-dose group than in low-dose group.
Study Overview
Status
Status
Conditions
Conditions
Intervention / Treatment
Intervention / Treatment
Study Type
Study Type
Phase
Phase
- Phase 4
Participation Criteria
Eligibility Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Description
Inclusion Criteria:
- Males and females age between 21 and 75 years
- Diagnosis of mild to moderate congestive heart failure
- Coronary angiography identifying coronary artery disease as the likely cause of congestive heart failure
- Left Ventricular (LV) ejection fraction between 20 to 40 percent on echocardiography or RNA
- Sinus rhythm
Exclusion Criteria:
- Insulin-dependent diabetes mellitus
- Hypertension (higher than 140/90 mmHg at rest)
- Use of sympatholytic agents such as clonidine, methyldopa, reserpine
- Significant non-cardiac disease, possibly affecting cardiovascular regulation
- Autonomic neuropathy of any cause
- Leg injuries with nerve damage
- Poor bladder control
- Recent history of alcoholism, drug abuse, significant psychiatric disorders
- Known adverse events to AT1-receptor blockers
- Unlikely to tolerate being off digoxin and off blockers of the RAS for a short period
- Ischemic event within past 3 months
- Serum creatinine higher than 200 mmol/L
- Patients taking digoxin for atrial fibrillation
- Patients who require treatment with aldactone
- Patients with more than mild stable angina while on beta-blockers and/or calcium antagonists
- Patients on coumadin
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Treatment
- Allocation: Randomized
- Interventional Model: Single Group Assignment
- Masking: Single
Number of Arms
Arms and Interventions
Participant Group / ArmParticipant Group / Arm |
Intervention / TreatmentIntervention / Treatment |
|---|---|
|
Active Comparator: Low dose losartan
|
25 mg losartan bid for 10 weeks
Other Names:
|
|
Active Comparator: High dose losartan
|
50 mg, 75 mg, or 100 mg bid for 10 weeks.
Dose will be determined by the medical doctor depending on patients' tolerability
Other Names:
|
What is the study measuring?
Primary Outcome Measures
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Effect of losartan on the sympathetic nervous system.
Time Frame: 10 weeks
|
Assessed by microneurographic recordings of muscle sympathetic nerve activity from the peroneal nerve.
|
10 weeks
|
Secondary Outcome Measures
Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Change in plasma catecholamines.
Time Frame: 10 weeks
|
Plasma catecholamines will be measured by High-performance liquid chromatography (HPLC).
Samples will be collected for plasma aldosterone, plasma renin and plasma angiotensin II.
|
10 weeks
|
|
Change in central hemodynamics.
Time Frame: 10 weeks
|
Invasive measurement of central hemodynamic parameters; heart rate, blood pressure, cardiac output (CO), pulmonary capillary wedge pressure (PCWP), right arterial pressure (RAP).
|
10 weeks
|
Collaborators and Investigators
Sponsor
Sponsor
Investigators
Investigators
- Principal Investigator: Markus P Schlaich, Baker IDI Heart & Diabetes Institute
Study record dates
Study Registration Dates
First Submitted
First Submitted
First Submitted That Met QC Criteria
First Submitted That Met QC Criteria
First Posted (Estimate)
First Posted
Study Record Updates
Last Update Posted (Actual)
Last Update Posted
Last Update Submitted That Met QC Criteria
Last Update Submitted That Met QC Criteria
Last Verified
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
Other Study ID Numbers
- Project 103-10
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