Beta blockers are widely used in the treatment of various cardiovascular conditions, such as high blood pressure, angina, heart rhythm problems and preventing repeat heart attacks. The use of the drugs in treating heart failure conditions is a more recent development.

The first trial which investigated the use of beta blockers as a treatment for heart failure was the MERIT-HF trial in 1999. In this trial the drug metoprolol was given to people with moderate to severe dysfunction of their left ventricles, resulting in a significant reduction in mortality. Subsequent ‘Cardiac Insufficiency Bisoprolol Studies’ (CIBIS) and other studies established the use of beta blockers, particularly bisoprolol due to its ability to focus predominantly on the cells on the heart, as a treatment for heart failure conditions.

The body has natural responses to ensure the circulation and the blood pressure are maintained within normal ranges during normal daily life. This contributes to our survival and ensures the body is able to adapt to varying circumstances, for example it we have to walk quicker, or perhaps run to catch a bus, or if we’re in danger. When further output is needed from the heart the adrenal glands, which are situated above the kidneys, release substances called catecholamines into the blood stream. The main catecholamine, adrenalin, acts on small cells in the heart and blood vessels, called beta-adrenergic receptors. The stimulation of these receptors increases the heart rate, blood pressure and the output from the heart.

When this response occurs because the heart is not pumping effectively, due to a condition like dilated cardiomyopathy, these attempts to make it work harder place an excess workload on the heart and can worsen symptoms. Bisoprolol acts to interrupt this process and blocks the beta-adrenergic receptors. This has the effect of reducing the workload on the heart by slowing the heart rate and reducing the pressure against which the heart is pumping. The slower heart rate also allows more time for the heart to fill will blood and improves the output each time it pumps.

Bisoprolol has to be given at a low dose initially, to allow the body to become accustomed to its action. The aim is then to gradually increase the dose over a period of weeks, either to 10mg or the maximum dose the person can tolerate. This can be a difficult time for some people as the drug lowers the heart rate and blood pressure, and this can result in symptoms of fatigue and dizziness. A standard protocol is used to guide the gradual increase in the dose of the drug. However, this has to sometimes be adapted according to the person’s response to the drug.

Bisoprolol, and similar beta blockers like carvedilol, are usually prescribed in combination with an ACE inhibitor, or an angiotensin II receptor blocker, and this therapy has become the cornerstone for the standard treatment of heart failure conditions.

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© Cardiomyopathy UK. March 2018.