Are Beta Blockers Effective in Preventing Heart Attacks? Here's What Recent Studies Say

It is quite common for doctors these days to prescribe beta-blockers to patients who have a weak heart with high blood pressure or have recently suffered a heart attack. Let us try to unravel how effective beta-blockers are in preventing heart attacks.

It's important to note that beta-blockers are no longer the go-to option for reducing blood pressure. While they may still be prescribed for heart disease patients, there are potentially more effective alternatives available for those with high blood pressure. That said, beta-blockers remain a popular treatment option for angina, as they can decrease the heart rate, lower the heart's oxygen demand, and reduce the frequency of angina attacks.

Beta-blockers are a class of medicines that block the effects of hormones like adrenaline on beta receptors, which are found on cells of the heart, blood vessels, lungs, and other organs. By blocking these receptors, beta-blockers slow down the heart rate, relax the blood vessels, lower the blood pressure, and help the heart beat more regularly. There are different types of beta receptors, and some beta-blockers are selective for one type over another.

Beta-blockers work mainly by slowing down the heart. They do this by blocking the action of hormones like adrenaline. Beta-blockers prevent adrenaline, a stress-related hormone, from making contact with your heart's beta receptors. This prevents adrenaline from making your heart pump harder or faster.

Beta-blockers are available in different formulas with different routes of administration, including oral, intravenous, and ophthalmic. Beta-blockers are usually taken once or twice a day with meals and should generally be taken at the same time every day. Always take your medication as prescribed.

Beta-blockers are prescription-only medicines, which means they can only be prescribed by a GP or another suitably qualified healthcare professional.

Here is a list of commonly used beta-blockers (generic name - trade name) in India:

Acebutolol - Sectral
Atenolol - Tenormin
Betaxolol - Kerlone
Bisoprolol - Zebeta, also sold as Ziac
Carteolol - Cartrol
Carvedilol - Coreg
Labetalol - Normodyne, also sold as Trandate
Metoprolol - Lopressor, also sold as Toprol

After a heart attack or acute myocardial infarction (AMI), beta-blockers like metoprolol and carvedilol are commonly prescribed. However, carvedilol may offer added benefits to certain patients due to its additional pharmacological properties. Specifically, for patients with a depressed left ventricular ejection fraction (LVEF) of 40% or lower, carvedilol was associated with improved survival when compared to metoprolol.

LVEF is an indicator of how much blood the heart chamber pumps out with each heartbeat.

No significant differences were observed in survival rates for patients with an LVEF greater than 40%. Nonetheless, it is important to conduct further prospective trials to validate these findings.

Some common side effects of beta-blockers include:

Fatigue
Cold hands or feet
Weight gain
Bradycardia (slower than normal heart rate)
Hypotension (low blood pressure)
Dizziness or lightheadedness
Depression
Shortness of breath or trouble breathing

However, recent studies have raised concerns about the long-term benefits of beta-blockers for these patients.

A study published in the journal Heart analyzed data from over 179,000 patients who had survived a heart attack and were treated with different medications. The researchers found that beta-blockers did not lower the mortality rate or the rate of recurrent heart attacks after one year, indicating that they may not reduce the risk of further heart attacks or death in people who do not have heart failure.

Similarly, another study published in the international journal BMJ Open reviewed 16 randomized trials involving more than 20,000 patients with high blood pressure. The researchers found that beta blockers did not reduce the risk of heart attack or stroke compared to other blood pressure-lowering drugs, suggesting that beta blockers may not be as effective as previously thought in preventing heart attacks.

These findings challenge current guidelines that recommend beta blockers as a first-line treatment for patients with high blood pressure or previous heart attack. The researchers suggest that beta blockers may still be useful for some patients, such as those with heart failure or angina, but they should not be routinely prescribed for everyone.

According to the data collected in real-time, long-term usage of beta blockers didn't appear to result in better cardiovascular outcomes over an average monitoring period of 4.5 years. Out of the individuals on beta blockers, 19% (6475) experienced adverse outcomes such as death from any cause, another heart attack, unscheduled revascularization, or hospitalization due to heart failure. In comparison, 22% (2028) of those who didn't take beta blockers had similar outcomes.

The researchers noted that this is an observational study, meaning it cannot establish causality. Although this study is the largest of its kind so far, there are certain limitations to the findings that should be taken into account. For instance, patients weren't randomly assigned to treatment, the study only included specific cardiovascular outcomes, and there was no information on how consistently patients took their medications or how their quality of life was impacted.

If you are taking beta blockers for your heart condition, it is important not to stop them without consulting your doctor. Your doctor can help you determine if beta blockers are still appropriate for you, or if you need to switch to another medication. Beta blockers can have side effects, including fatigue, cold hands and feet, weight gain, and depression. You should also regularly monitor your blood pressure and adopt a healthy lifestyle to reduce your risk of heart problems.