In a nutshell
This study compared the effects of bisoprolol (Zebeta, Concor) and atenolol (Tenormin) on sympathetic nervous activity (SNA) and central aortic pressure (CAP) in patients with essential hypertension.
Some background
Essential hypertension, also called primary hypertension, is a rise in blood pressure of unknown cause. Essential hypertension tends to develop gradually over many years. There are different types of drugs that are recommended for treatment of essential hypertension. Both bisoprolol and atenolol are part of a class of blood pressure lowering drugs called beta blockers. Beta blockers target some proteins (beta receptors) found in the heart muscle, blood vessels and other organs that are part of the sympathetic nervous system (SNS). The SNS reacts to the hormone epinephrine and leads to stress responses (which lead to an increase in heart rate and blood pressure). Beta blockers interfere with the binding of the beta receptor, thus weakening the effect of the stress response. As a result, in the heart, beta blockers reduce heart rate and blood pressure.
SNA is the activity of the SNS and is responsible for regulating the body's internal environment. SNA can cause changes in blood pressure through the action of the baroreceptors (sensors located in the blood vessels that detect changes in blood pressure). CAP is the pressure in the aorta, which is the largest artery in the body that originates directly from the heart. Previous studies have shown that CAP is strongly associated with the risk of developing heart disease. This study aimed to evaluate the effects of bisoprolol and atenolol on SNA and CAP in patients with essential hypertension and controlled heart rate.
Methods & findings
A total of 109 hypertensive patients who have never been treated for hypertension were involved in this study. 54 patients were randomly assigned to receive bisoprolol 5 mg, while 55 patients received atenolol 50 mg for 4 to 8 weeks. Patients were followed every 2 weeks for blood pressure control, CAP and SNA. SNA was measured through the sensitivity of the baroreceptors (baroreflex sensitivity or BRS).
Results showed that blood pressure was similarly reduced in both groups. However, the decrease in the CAP was significantly greater in the bisoprolol group compared to the atenolol group. Also, BRS was higher in patients treated with bisoprolol than in the atenolol group. However, at the end of the study, when the target heart rate was achieved, BRS was similar in both treatment groups. No serious side effects were reported in either treatment groups.
The bottom line
In summary, this study showed that bisoprolol is more effective than atenolol in the reduction of CAP.
The fine print
This study included a very small number of patients. Larger studies are needed to confirm these results. Also, further studies are needed to determine the effects of bisoprolol in reducing the risk of heart disease in relation to CAP.
What’s next?
Ask your doctor which blood pressure lowering drugs are more appropriate in your situation.
Published By :
PLOS ONE
Date :
Sep 10, 2013
