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Beta-Blockers Don’t Block Heart Attacks or Stroke

By: 
Renee Despres
Monday, February 20, 2017 - 05:19pills; medications

Beta-blockers, a type of drug frequently prescribed for people with heart disease, may not reduce the risk of a second heart attack, death, or stroke in people with coronary artery disease (CAD). In people with risk factors for heart disease, beta-blockers may increase the risk of such events, according to findings from a recent large observational study conducted by a team of investigators from the Cardiac and Vascular Institute at NYU Langone Medical Center.

Beta-blockers, which lower blood pressure and decrease heart rate, have been widely prescribed for years. They are commonly part of a hypertension treatment regime and are often prescribed long-term for anyone who has had a heart attack Because they lower blood pressure and slow heart rate, they can help a heart that’s not getting a full supply of oxygen and nutrient-rich blood so it won’t have to work as hard – or so the thinking goes.

But findings from the study, which were published in the October 3, 2012 issue of the Journal of the American Medical Association (JAMA), suggest that beta-blockers do not lower the risk of heart attacks, death, or stroke in people with coronary artery disease (CAD) or risk factors for CAD, including people with a history of heart attack.

 Nice to Know: What Do Beta-Blockers Do?

Beta-blockers – their fancy name is “beta-adrenoceptor blocking agents” – are widely prescribed for people with coronary artery disease.

Coronary artery disease, often abbreviated “CAD,” occurs when plaque builds up in arteries that feed the heart. Beta blockers slow the heart and lower blood pressure by stopping the action of adrenaline and other “fight-or-flight” hormones. The drugs bind to special receptors on the heart called “beta-adrenoceptors.” They essentially take up a parking space, preventing adrenaline and other hormones from “parking” in same spot – that is, binding to the beta receptors and telling the heart to work faster.

Common beta-blockers include atenolol, labetalol, bisoprolol, carvedilol, propanolol, metopolol, nadolol, acebutolol, and timolol.

The study was led by Sripal Bangalore, MD, assistant professor in the Department of Medicine at the Leon H. Charney Division of Cardiology. Bangalore’s team reviewed the health records of 44,708 people who were enrolled in the international Reduction of Atherothrombosis for Continued Health (REACH) registry.  People enrolled in the registry were at least 45 years old and had some sort of coronary artery disease.

Investigators divided the people into three groups: people who had previously experienced a heart attack, people who had CAD but had not had a heart attack, and people who simply had risk factors for heart disease such as diabetes, smoking, or high blood pressure. Researchers followed participants for 44 months (three and a half years), noting who was taking beta-blockers and who wasn’t.

People who used beta-blockers experienced the same number of fatal and nonfatal heart attacks and strokes as people who didn’t use the drugs. In the group with only risk factors, those who took beta-blockers fared worse than those who did not take the drugs.

ehealthMD spoke with Bangalore about his findings -- and what they could mean for the millions of people taking beta-blockers.

ehealthMD: Let’s start with the basics. What are beta-blockers?

Dr. Bangalore: Beta-blockers are a class of medication that opposes the action of catecholamine –adrenaline and its cousins. They block the action on the heart and several other receptors. So they reduce the heart rate and bring blood pressure down. 

ehealthMD:  Why are beta-blockers prescribed?

Dr. Bangalore: For patients who are having a heart attack, reducing heart rate and blood pressure is helpful. A heart attack or coronary artery disease reduces blood supply, but as the heart beats faster, it needs more blood to function – it’s a case of mismatched supply and demand. So beta-blockers are given to reduce the workload (demand) on the heart.

Beta-blockers are also prescribed for patients with heart failure. The goal is to improve the heart’s pumping ability and make it stronger.

Most of the clinical trials of beta-blockers were done in people who were having a heart attack, and they’ve shown that beta-blockers help during and immediately after a heart attack. So physicians have extrapolated from those studies to other settings – for instance, patients that have heart disease but have not had a heart attack or who have risk factors for heart disease. 

ehealthMD: When were beta-blockers first developed?  

Dr. Bangalore: Beta-blockers were developed about 40 to 50 years ago. Many beta-blockers are now available as generic medications.

ehealthMD: What’s the importance of this study?

Dr. Bangalore: There were three populations in the study. One group had risk factors for CAD, another had had a prior heart attack, and the third had CAD without having had a heart attack. We saw astonishingly little difference for any of the groups.

All of the people in the study were stable patients – they were not actively having a heart attack. We followed them after the fact, a few months or a year later. These were the patients we looked at. Some were on beta-blockers and some were not on beta-blockers. In terms of reducing the risk of future cardiovascular events, we found no difference. 

For clinicians, these results are very interesting. People generally think that beta-blockers do a lot of good, and physicians often reinforce to patients that “These are great medications and you should take them.” So we said, “Let’s go back to data to make sure this therapy is beneficial.” And it turns out that it might not be.

ehealthMD: What are the risks of beta-blocker use?

Dr. Bangalore: Beta-blockers have a lot of side effects, including headache, upset stomach, and erectile dysfunction. Fatigue is a common side effect – one that decreases the amount that people tend to exercise. Conversely, exercise is a lifestyle factor known to reduce the risk of heart disease. In people without diabetes, beta-blockers may slightly increase the risk that they will develop diabetes. The drugs may interfere with lipid control, and cholesterol levels might go up slightly; weight gain is common, as well. These side effects are especially troubling in patients trying to reduce risk factors for heart disease through lifestyle changes like weight loss and increased exercise.  

These are well known side effects of the drugs, and they may interfere with people’s ability to continue taking the drugs. Many studies show that even in patients who have had a heart attack, less than 30-40 percent of people continue to take the drugs past one year. Often, they don’t continue because they cannot tolerate those medications. 

ehealthMD: You write that with the advent of modern reperfusion or medical therapy, the use of beta-blockers might not need to be as widespread. How have those therapies potentially changed the need for beta-blockers?  

Dr. Bangalore: Beta-blockers have been around for four or five decades now. Some of the data about their use, especially in patients after a heart attack, are based on studies done in the 1980s and 1990s. Treatments were not the same then as in this day and age. People weren’t rushed to the cath lab to open blockages or given powerful clot-busting drugs.

Likewise, medical therapy has evolved since then. One of the most important advances in medical therapy is the development of statins. Statins do wonders to reduce the risk of cardiovascular disease.

This may be why we did not find benefit in patients who have had a prior heart attack. Damage to the heart muscle may be much less, and heart failure may not be the issue.

We’ve had no data about beta-blocker use for the other two groups – those who have only risk factors and those with coronary artery disease but no history of heart attack. What has happened is physicians are extrapolating results from patients who have had a heart attack to those who have not.  

ehealthMD: Do your results align with current American Heart Association recommendations?

Dr. Bangalore: In a way, it aligns with the American Heart Association recommendation, which is to prescribe a beta-blocker for up to three years after a heart attack. We don’t know if that is correct, whether one year or three years is best, is what the guidelines are saying. In reality, though, most doctors who prescribe beta-blockers are keeping their patients on them on for life.

ehealthMD: What patients should be getting beta-blockers?

Dr. Bangalore: As of now, we know that beta-blockers are effective in patients who are acutely having a heart attack. In these patients, beta-blocker use is effective during the event and maybe short term afterwards. They should also be used in patients with heart failure. In heart failure, the heart becomes weak. Controlling blood pressure and heart rate can reduce the workload on the weakened heart. In heart failure, drugs should definitely be prescribed longer term.

ehealthMD: Do you think this study will change clinical practice?

Dr. Bangalore: It’s an observational study, so additional studies need to be completed before we can make specific suggestions for changing clinical practice. But it’s a good reminder for physicians, before they prescribe a beta-blocker, to stop and take the time to think, “Why am I prescribing this medication? Is there any clear evidence of its benefit?” If the answer is that there’s no benefit from randomized trials in the past, then perhaps they shouldn’t prescribe it.

On the other hand, there are very good uses for beta-blockers. If the answer is “for atrial fibrillation, just to control the heart rate,” that’s a good enough reason. They should not be prescribed solely for longer life, or to reduce the risk of heart attack or stroke. But if they’re prescribed to, for instance, control migraine – that’s a good enough reason. As long as the physician is not using them for prolonging life.

ehealthMD: What’s next? What else do we need to know about beta-blockers?

Dr. Bangalore: We need good clinical trials. How long should we be giving these drugs to people after a heart attack? We should start clinical trials that will guide us in terms of their use.

ehealthMD: If I’m a person taking a beta-blocker, what should I do?

Dr. Bangalore: The first and foremost thing: Do not take it upon yourself to stop these medications. We know that abruptly stopping these medications can be dangerous. However, it is not unreasonable to have a discussion with your physician and figure out why the drug is being prescribed. In many cases it may be for the right reason. But a frank discussion with the prescribing physician will help people to figure out the best option for them.