Protective prior to noncardiac surgery in persons at high risk of complications
What the Research Shows
Numerous studies suggest that beta-blockers can reduce mortality by 25% to 40% in patients with certain kinds of heart failure, and cut sudden cardiac death up to 50% in patients with a recent heart attack. One study in the October 29, 2002 issue of
found that those taking beta-blockers had 15% to 38% less risk of dying compared with those not taking these drugs. The death rates for beta-blocker patients were 16% at two years and 34% at five years, significantly lower than the death rates of 27% at two years and 50% at five years for patients not receiving beta-blockers. Beta-blocker therapy, however, did not significantly decrease the risk of cardiac arrest or death from heartbeat irregularities of the people in this study, though there was a trend toward this type of benefit.
Another study in the May 1, 2002 issue of the
Journal of the American Medical Association
looked at close to 630,000 people undergoing
coronary artery bypass surgery
and found that using beta-blockers before surgery significantly helped to increase survival when compared to not using beta-blockers before the heart surgery.
Mechanism for How It Works
Beta-blockers "block" the effects of adrenaline on your body's beta-receptors. This slows the nerve impulses that travel through the heart. As a result, your heart does not have to work as hard because it needs less blood and oxygen. This decreases heart rate, blood pressure, and lessens the need for nitrates. Beta-blockers also block the impulses that can cause an arrhythmia (abnormal heart beat).
Beta-blockers generally work by affecting the response to some nerve impulses. Your body has two main beta-receptors: beta 1 and beta 2. Some beta-blockers are selective, which means that they block beta 1 receptors more than they block beta 2 receptors. Beta 1 receptors are responsible for heart rate and the strength of your heartbeat. Nonselective beta-blockers block both beta 1 and beta 2 receptors. Beta 2 receptors are responsible for the function of your smooth muscles (muscles that control body functions but that you do not have control over).
This class of drugs may decrease the sympathetic outflow from the central nervous system and/or suppress the release of renin—a substance that is elevated in some patients with high blood pressure and is involved in a cascade of events leading to constriction of blood vessels. In addition, some speculate that beta-blockers may have possible antioxidant and cholesterol lowering effects.
Allergen immunotherapy (allergy shots)
Allergen extracts for skin testing
—Beta-blockers may increase the risk of serious allergic reaction to these medicines.
(diabetes medicine you take by mouth)
(histamine blocker)—may increase effect of beta-blockers
(eg, Catapres)—This may reverse blood pressure-lowering effects of beta-blockers and vice versa. A doctor should monitor blood pressure carefully if these drugs are being mixed.
—This may block the effects of beta-blockers; in addition, there is an increased risk of high blood pressure, fast heartbeat, and possibly heart problems when using cocaine while taking a beta-blocker.
(adrenaline)—Blood pressure can dramatically increase. Avoid taking this drug with beta-blockers.
(eg, Wytensin)—The effects on blood pressure may be increased. In addition, unwanted effects may occur if clonidine, guanabenz, or a beta-blocker is stopped suddenly after use together.
—Beta-blockers may prolong and cover up certain symptoms of
(low blood sugar), such as increases in pulse rate and blood pressure, and may make the hypoglycemia last longer.
Monoamine oxidase (MAO) inhibitors
(furazolidone [eg, Furoxone], isocarboxazid [eg, Marplan], phenelzine [eg, Nardil], procarbazine [eg, Matulane], selegiline [eg, Eldepryl], tranylcypromine [eg, Parnate])—Taking beta-blockers while you are taking or within 2 weeks of taking monoamine oxidase (MAO) inhibitors may cause severe high blood pressure.
Nonsteroidal anti-inflammatory Drugs
—These may reduce the blood pressure-lowering effects of beta-blockers.
—This may reduce the effectiveness of beta blockers.
(eg, Somophyllin-T)—The effects of these medicines and beta-blockers may be blocked when combined. Also, theophylline levels in the body may be increased, especially in people who smoke.
Do not take the following with beta-blockers except on medical advice:
Calcium—This supplement may decrease blood levels of beta-blockers.
Chromium—Beta-blockers have been known to reduce levels of HDL "good" cholesterol. According to one study, chromium supplementation can help offset this adverse effect.
Coenzyme Q10—Beta-blockers might impair the body's ability to utilize coenzyme Q10 (CoQ10), which appears to play a significant role in normal heart function. Depletion of CoQ10 might be responsible for some of the side effects of beta-blockers.
Coleus forskohlii—This relaxes blood vessels and might have unpredictable effects on blood pressure if combined with beta-blockers.
Other Potential Concerns
The following should be considered if you are taking beta-blockers:
These conditions can affect the use of beta-blockers:
Allergy or intolerance to beta-blockers as well as
emphysema—increased breathing troubles and the severity/duration of allergic reactions
(unusually slow heartbeat) or heart/blood vessel disease—heart function could be further decreased
Diabetes—circulation problems, hyperglycemia, and masking of some of the symptoms of low blood sugar
Kidney or liver disease—the effects of beta-blockers may be increased because it is more slowly removed from the body
Overactive thyroid—Symptoms can be increased when beta-blockers are stopped; they may also cover up the fast heartbeat, which is a sign of overactive thyroid.
Breastfeeding—Beta-blockers can be passed into breast milk and cause problems, such as slow heartbeat, low blood pressure, and trouble breathing in nursing babies. Mothers who wish to breastfeed while they are taking beta-blockers should consult a doctor.
Children—Some beta-blockers have been used in children and have generally not been shown to cause different effects or problems in children than those seen in adults.
Older adults—This population is usually more sensitive to the effects of beta-blockers, and some side effects are more likely to occur. The drugs may reduce tolerance to cold temperatures.
Pregnancy—Low blood sugar, breathing problems, a lower heart rate, and low blood pressure have been observed in newborn infants whose mothers took beta-blockers during pregnancy.
: Consult a doctor before taking any medications when pregnant.
What to Watch for (Physical/Biochemical/Physiological)
Common side effects:
Cold hands and feet
Drowsiness or fatigue
Dry mouth, eyes, and skin
Weakness or dizziness
Less common side effects:
Swelling of the hands and feet
Trouble sleeping or vivid dreams while asleep
Wheezing, trouble breathing, or shortness of breath (While not very common, this side effect can occur in people with chronic lung disease and may be serious or fatal).
Secondary prevention includes 1) identifying and treating people with established disease and those at very high risk of developing cardiovascular disease, and 2) treating and rehabilitating people who have had a heart attack or stroke to prevent another cardiovascular or cerebrovascular event.
The American Heart Association recommends the following uses for beta-blockers as secondary prevention:
Start in high-risk post-myocardial infarction patients (arrhythmia, left ventricular dysfunction, inducible ischemia) at 5 to 28 days.
Continue six months minimum. Observe usual contraindications.
Use as needed to manage angina, rhythm or blood pressure.
Take only the amount of beta-blocker ordered by your doctor
Do not stop taking this medicine for any reason without first checking with the doctor who directed you to take it.
Tell you doctor or dentist about taking this medicine before having any kind of surgery (including dental surgery) or emergency treatment
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a