A Note to our Audience

September 25, 2009

Beta blockers are extremely commonly used medications used for a variety of reasons. As we complied our research and our thoughts, we discovered a greater amount of controversy than previously expected regarding the uses of beta blockers in managing hypertension and for peri-operative usage.

Once you read our postings, we look forward to hearing from you! Your thoughts, opinions, and questions will only broaden our perspective on the use of these drugs in clinical practice. Please be sure to also participate in our anonymous surveys as well.

What is a Beta Blocker?

September 25, 2009

Beta BlockersBeta blockers, also known as beta-adrenergic blocking agents, are drugs that block norepinephrine and epinephrine from binding to beta receptors. There are three types of beta receptors and they control several functions based on their location in the body.

Beta-1 (β1) receptors are located in the heart, eyes, and kidneys.

Beta-2 (β2) receptors are located in the lungs, gastrointestinal tract, liver, uterus, blood vessels, and skeletal muscles.

Beta-3 (β3) receptors are located in fat cells.

Beta blockers work primarily to block β1 and β2 receptors. By blocking the effect of norepinephrine and epinephrine, beta blockers are capable of reducing the heart rate and reducing the blood pressure by dilating blood vessels.

Beta blockers differ in the type of beta receptors they block and, therefore, their effects.

• Non-selective beta blockers, such as propranolol (Inderal), block β1 and β2 receptors. Therefore, non-selective beta blockers affect the heart, blood vessels, and air passages.

• Selective beta blockers, such as metoprolol (Lopressor, Toprol XL) primarily block β1 receptors. Therefore, selective beta blockers mainly act on the heart and do not affect air passages.

• Some beta blockers, such as pindolol (Visken), have intrinsic sympathomimetic activity (ISA), which means they mimic the effects of epinephrine and norepinephrine and can cause an increase in blood pressure and heart rate. Beta blockers with ISA have smaller effects on heart rate than agents that do not have ISA.

• Labetalol (Normodyne, Trandate) and carvedilol (Coreg) block beta and alpha-1 receptors. By also blocking alpha receptors, there is great blood vessel dilation involved.

References:
Medicine Net: Beta Blockers (http://www.medicinenet.com/beta_blockers/article.htm)

RX List: Beta Blockers (http://www.rxlist.com/script/main/art.asp?articlekey=79790)

Indications/Contraindications in the Use of Beta Blockers

September 25, 2009

The following conditions are currently approved by the Federal Food and Drug Administration for treatment by beta blockers:

• angina
• atrial fibrillation
• atrial flutter
• glaucoma
• hypertension
• idiopathic hypertrophic subaortic stenosis
• migraine prophylaxis
• myocardial infarction prophylaxis
• myocardial infarction
• ocular hypertension
• paroxysmal supraventricular tachycardia
• pheochromocytoma
• thyrotoxicosis
• tremor
• ventricular arrhythmias

Beta blockers have also been documented as prescribed for the following conditions; however, these indications are not approved by the Federal Food and Drug Administration at this time.

• esophageal varices
• ethanol withdrawal
• hypertensive emergency
• hypotension induction
• peri-operative hypertension

Considerable care needs to be exercised if a beta blocker is given in conjunction with cardiac selective calcium-channel blockers because of their additive effects in producing electrical and mechanical depression. Except for those drugs specifically approved for use in heart failure, beta blockers are contraindicated in heart failure patients. Beta blockers are also contraindicated in patients with sinus bradycardia and partial AV block.

Bronchoconstriction can occur, especially when non-selective beta-blockers are administered to asthmatic patients. Therefore, non-selective beta-blockers are contraindicated in patients with asthma or chronic obstructive pulmonary disease. Hypoglycemia can occur with beta-blockers because β2-adrenoceptors normally stimulate hepatic glycogen breakdown and pancreatic release of glucagon, which work together to increase plasma glucose. Therefore, blocking β2-adrenoceptors lowers plasma glucose. Therefore, beta-blockers are to be used cautiously in diabetics.

On an interesting note, professional golfers are not allowed to use beta blockers because of the off label use by professional golfers to combat anxiety. This is a new, yet ongoing, issue that will continue to develop as time progresses.

References:
Federal Food and Drug Administration (www.fda.gov)

Rx List: Beta Blockers (http://www.rxlist.com/script/main/art.asp?articlekey=79790)

Medicine Net: Beta Blockers (http://www.medicinenet.com/beta_blockers/article.htm)

Golf Dash (http://golfdash.blogspot.com/2006/08/drugs-in-professional-golf-again.html)

Sports Illustrated and Golf Magazine (http://www.golf.com/golf/tours_news/article/0,28136,1663705,00.html#)

Risk/Benefit Analysis of the Use of Beta Blockers

September 25, 2009

Over the past several years, evidence has been accumulating that shows beta blockers are useful drugs in treating heart failure. A study named the COPERNICUS trial tested the use of beta blockers in 2200 patients. The patients were randomly assigned to either the carvedilol treatment group or the placebo treatment group. Both groups were given ACE inhibitors, diuretics, and digitalis. The results showed a 35% improvement in patients who received the carvedilol and was even greater in patients with very severe heart failure. These patients also did no show any additional side effects than those treated with the placebo. Similar studies were also done using bisoprolol and metoprolol with comparable results. These drugs have been proven to not only improve quality of life, but also improve the chances of survival (Fogoros).

It has also been shown that post myocardial infarction, beta blockers are effective in preventing further MIs or other life threatening cardiac events while calcium-channel blockers have been shown to be ineffective. The explanation for this is still unknown, but the evidence is overwhelming in favor of beta blockers (Singh).

Another study, the Survival and Ventricular Enlargement or SAVE trial, showed that the use of beta blockers resulted in a 30% reduction in cardiac death, a 21% reduction in heart failure, and an 11% reduction in recurrent MIs 42 months post MI (Herrmann).

Studies have also shown that beta blockers are equally effective in men and women (American Heat Association).

A study done by the School of Pharmacy and Institute for Health Policy Studies showed that using beta blockers for all MI survivors, except those with significant contraindications, in the year 2000 and remained on the medication for 20 years would result in 4300 fewer CHD deaths, 3500 MIs prevented, and 45,000 life-years gained compared with current use. If this policy were carried out over 20 years, beta blockers would save $18 million and result in 72,000 fewer CHD deaths, 62,000 MIs prevented, and 447,000 life-years gained (Phillips).

Researchers at the Keck School of Medicine showed that beta blockers were also useful in reducing the risk of death in patients with chronic severe mitral regurgitation or congestive heart failure with normal ejection fraction. The study showed that 65% of these patients on a beta blocker were alive after five years, while only 50% of those not on a beta blocker were alive (Ramdas

Every drug comes with its side effects. When taking a beta blocker, syncope, often referred to as dizziness or lightheadedness, is a side effect that may be strongest when you change position, such as from laying to sitting or standing. Fatigue, headaches, and insomnia can also accompany this class of drugs. Weight gain is more common as your doctor increases the dose of the medication you receive. Dyspnea, bradycardia, and arrhythmias have also been reported with patients using beta blockers. Another side effect that only affects men is impotence. A study in the October 20, 2008 issue of Health Day News showed that the death rate for people given beta blockers before a non-cardiac surgery was ten times higher and the rate of post-operative acute myocardial infarctions was four times higher in the thirty days following an operation than those not getting the drugs. Beta blockers may also cause hyperglycemia; therefore, diabetic patients prescribed beta blockers must be closely monitored. If you are not a diabetic, beta-blockers may also increase your chances of developing diabetes.

After evaluation of the evidence along with consideration of outside sources, we found that many cardiologists agree that caution must be exercised in prescribing beta blockers because it may harm some patients but can clearly benefit others who are at the highest risk of complications post-operatively and with risk factors for cardiovascular disease (Bio-Medicine).

References:
Bullock, C. (2002, March 11). In heart failure, beta-blockers boost survival advantage for women [Online exclusive]. Bio-Medicine. Retrieved from http://news.bio-medicine.org/medicine-news-2/In-heart-failure–beta-blockers-boost-survival-advantage-for-women-8668-1/

Fogoros, R.N. (2003, November 30). Beta blockers in heart failure [Online exclusive]. About.com. Retrieved from http://heartdisease.about.com/cs/heartfailure/a/bbinhf.htm
Herrmann, H.C. (1997, March 11). Beta blockers add benefits after MI [Online exclusive]. Journal Watch. Retrieved from http://cardiology.jwatch.org/cgi/content/full/1997/311/1

Phillips, K.A., Shlipak, M.G., Coxson, P., Heidenreich, P.A., Hunink, M.G.M, Goldman, P.A., Williams, L.W., Weinstein, M.C., & Goldman, L. (2000, December 6). Health and economic benefits of increased beta-blocker use following myocardial infarction. The Journal of the American Medical Association, 284, 2748-2754. Retrieved from http://jama.ama-assn.org/cgi/content/abstract/284/21/2748

Singh, B.N.(1990, September 5). Advantages of beta blockers versus antiarrhythmic agents and calcium antagonists in secondary prevention after myocardial infarction [Web exclusive]. The American journal of cardiology. Retrieved from http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=Retrieve&list_uids=1699400&dopt=abstractplus

Varadarajan, P., Appel, D., Joshi, N., Duvvuri, L., & Pai, R.G. (2005, March 8). Beta-blockers may help broader group of patients with heart problems [Online exclusive]. Medical News Today. Retrieved from http://www.medicalnewstoday.com/articles/20875.php

Controversy Regarding the Use of Beta Blockers: Peri-Operatively

September 25, 2009

ORThere is currently a great deal of controversy regarding the use of beta blockers peri-operatively. According to a recent study by researchers at Boston University, the death rate for people given beta blockers before non-cardiac surgery was ten times higher in the thirty days after an operation for those receiving beta blockers at 2.52% of patients as opposed to those not receiving the drugs at 0.25% of patients. The incidence of an acute myocardial infarction was four times higher at 2.94% of patients for those receiving beta blockers than for those not receiving beta blockers at 0.74% of patients.

Beta blockers are commonly given before surgery to reduce cardiac risk by slowing the heart rate. The Boston study found that the risk of problems was mainly seen in those whose heart rates remained high despite beta-blocker treatment.

These new results differ somewhat from those of a major international study reported earlier this year. The POISE study of 8,351 people having non-cardiac surgery found a 27% reduction in heart attacks but an overall 33% higher death rate for those getting beta blockers. (Archives of Surgery, October 2008)

The American College of Cardiology recommends fifty to sixty beats per minute before surgery and not to exceed eighty beats per minute.

References:
New England Journal of Medicine (http://content.nejm.org/cgi/content/extract/344/22/1711)

American College of Cardiology (http://www.acc.org)

Haytham M. A. Kaafarani; Prasad V. Atluri; John Thornby; Kamal M. F. Itani, “β-Blockade in Noncardiac Surgery: Outcome at All Levels of Cardiac Risk,” Archives of Surgery, Oct 2008; 143: 940 – 944. Retrieved from http://archsurg.ama-assn.org/cgi/content/full/143/10/940?maxtoshow=&HITS=10&hits=10amp;RESULTFORMAT=&fulltext=beta+blockers&searchid=1&FIRSTINDEX=0amp;resourcetype=HWCIT

Controversy Regarding the Use of Beta Blockers: Managing Hypertension

September 25, 2009

Another paper published in the October 28, 2008 issue of the Journal of the American College of Cardiology raises doubts about the use of beta blockers to control high blood pressure.

According to the report from cardiologists at the Columbia University College of Physicians and Surgeons, analysis of data from nine controlled trials found a higher incidence of death, acute myocardial infarction, stroke, and heart failure in patients whose heart rate was lowered by beta-blocker treatment.

A third article published in Medical News Today in June 2006 also suggests that beta blockers should not be used as a first line therapy in treating hypertension. This study was conducted by the National Institute for Health and Clinical Excellence (NICE) in England and suggests that there are numerous other drugs available for treating hypertension that are better suited than beta blockers.

Reference:
Medical News Today (http://www.medicalnewstoday.com/articles/46131.php)

Poll: Do You Take A Daily Beta Blocker?

September 25, 2009

Poll: Use of Beta Blockers Peri-Operatively

September 25, 2009

Interviews with Medical Professionals

September 25, 2009

In Summary…

September 25, 2009

Beta-blockers are indicated for a variety of different ailments, however, much thought and research should be done by the patient and the physician before the patient takes a beta-blocker. Beta-blockers are most effective in treating cardiovascular conditions in which the heart is being overworked and stressed because the beta receptors are directly on the heart. A common concern for most patients who are considering taking a beta-blocker is the long list of side effects that beta-blockers can cause. Although there are some very serious potential side effects such as bradycardia, arrhythmias, and dyspnea, in most cases the benefit of taking a beta-blocker outweighs the risk of the side effects. Such an example is using a beta-blocker to prevent any future myocardial infarctions. It is imperative that everything be done to prevent another MI, and so a patient taking a beta-blocker in this situation would outweigh the risks of other side effects. Much controversy still exists over the use of beta-blockers peri-operatively, however, in many instances beta-blockers are still used for this reason despite the mortality rate in peri-operative use.

Links to additional resources are listed below.

Journal of the American College of Cardiology

http://content.onlinejacc.org/

Archives of Surgery

http://archsurg.ama-assn.org/

Medicine Net

http://archsurg.ama-assn.org/

American Heart Association

http://www.americanheart.org

American College of Cardiology

http://www.acc.org

New England Journal of Medicine

http://content.nejm.org/cgi/content/extract/344/22/1711

Federal Food and Drug Administration

http://www.fda.gov


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