Study of High Dosage of Losartan in Comparison to Low Dose of Losartan in Heart Failure Patients
Status:
Withdrawn
Trial end date:
1969-12-31
Target enrollment:
Participant gender:
Summary
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.
Phase:
Phase 4
Details
Lead Sponsor:
Baker Heart and Diabetes Institute Baker IDI Heart and Diabetes Institute