How Beta-Blockers Affect Your Heart and ECG

Hi there, Heart Warrior! Have you ever felt your heart race before a big presentation, or pound in your chest during a stressful moment? That familiar surge is your body’s “fight or flight” response, powered by a hormone called adrenaline. While this is a normal and even helpful reaction in certain situations, for some of us, our hearts can be a little too responsive to adrenaline, leading to conditions like high blood pressure or a racing heart. This is where a class of medications called Beta-Blockers comes in.

At Qaly, we believe that understanding the medications you take is just as important as understanding your ECG readings. So today, we’re taking a closer look at Beta-Blockers, one of the most commonly prescribed medications for heart conditions. We’ll explore how they work, what they’re used for, and what you can expect to see on your ECG when you’re taking them.

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What Are Beta-Blockers?

Think of Beta-Blockers as a shield for your heart. They work by blocking the effects of adrenaline (also known as epinephrine) on your body’s beta receptors. These receptors are found in various parts of your body, including your heart, blood vessels, and lungs. When adrenaline binds to these receptors, it causes your heart to beat faster and with more force, and your blood vessels to constrict. By blocking these receptors, Beta-Blockers help to:

• ‍Slow down your heart rate: This gives your heart more time to fill with blood between beats, allowing it to pump more efficiently.‍
• Reduce the force of your heart’s contractions: This lowers the workload on your heart muscle.‍
• Relax your blood vessels: This helps to lower your blood pressure.

In essence, Beta-Blockers help your heart to work less hard, which can be incredibly beneficial for a variety of heart conditions.

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Types of Beta-Blockers

Not all Beta-Blockers are the same! They are generally categorized into two main types:

• ‍Selective Beta-Blockers: These primarily block beta- receptors, which are mostly found in the heart. This makes them a good choice for people with certain lung conditions like asthma or COPD, as they are less likely to affect the airways. Examples include metoprolol (Lopressor, Toprol XL) and atenolol (Tenormin).‍
• Non-Selective Beta-Blockers: These block both beta- and beta- receptors (found in the heart, lungs, and blood vessels). While effective for heart conditions, they can sometimes cause side effects related to the lungs. Examples include propranolol (Inderal) and nadolol (Corgard).

Your doctor will choose the best type of Beta-Blocker for you based on your specific condition and overall health.

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Why Are Beta-Blockers Prescribed?

Beta-Blockers are a versatile class of medications used to treat a wide range of cardiovascular conditions. Your doctor might prescribe a Beta-Blocker if you have:

• ‍High Blood Pressure (Hypertension): By relaxing blood vessels and slowing the heart rate, Beta-Blockers can effectively lower blood pressure.‍
• Angina (Chest Pain): Angina occurs when the heart doesn’t get enough oxygen-rich blood. Beta-Blockers reduce the heart’s oxygen demand by slowing it down, which can prevent or reduce the frequency of angina episodes.‍
• Arrhythmias (Irregular Heart Rhythms): Beta-Blockers are very effective at controlling fast heart rhythms like atrial fibrillation (Afib) and supraventricular tachycardia (SVT). They can also help to prevent dangerous ventricular arrhythmias.
• Heart Failure: In some cases of heart failure, where the heart muscle is weakened, certain Beta-Blockers can actually improve the heart’s function over time and help patients live longer.
• Previous Heart Attack: After a heart attack, Beta-Blockers can help to protect the heart from further damage and reduce the risk of another heart attack.

Beyond heart conditions, Beta-Blockers are also sometimes used to treat migraines, anxiety, and certain types of tremors.

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Beta-Blockers and Your ECG: What to Expect

If you’re taking a Beta-Blocker and using a smartwatch or other device to monitor your ECG, you might notice some changes in your readings. This is completely normal and expected! Here’s what you might see:

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Slower Heart Rate (Sinus Bradycardia)

‍The most common effect of beta-blockers on your ECG is a lower heart rate. These medications work by slowing down the electrical signals that trigger each heartbeat. As a result, your resting heart rate may drop below your usual baseline, often falling into the range of 50 to 60 beats per minute (bpm). This is typically a sign that the medication is working as intended.

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For many people, especially those who are athletic or naturally have a lower resting heart rate, this drop is perfectly normal. However, if your heart rate consistently falls below 50 bpm, or if you start experiencing symptoms like dizziness, fatigue, or shortness of breath, it could indicate that your heart is being slowed down too much. These signs are worth monitoring, particularly if they appear alongside other ECG changes such as a prolonged PR interval.

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Prolonged PR Interval

‍The PR interval on your ECG represents the time it takes for the electrical signal to travel from the top chambers of your heart (the atria) to the bottom chambers (the ventricles). Beta-blockers can slow down this signal, often leading to a slightly longer PR interval. A normal PR interval ranges from 120 to 200 milliseconds. When it goes beyond 200 ms, it’s considered prolonged.

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Mild prolongation (around 200–220 ms) is often harmless and can be expected with certain medications like beta-blockers. However, if the PR interval starts creeping above 230–250 ms, or if it’s progressively increasing over time, it may be a sign of more significant conduction delay. This could be worth watching closely, especially if accompanied by other symptoms like fatigue, lightheadedness, or skipped beats.

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Common Side Effects of Beta-Blockers

Like all medications, Beta-Blockers can cause side effects in some people. Most side effects are mild and tend to go away as your body adjusts to the medication. The most common side effects include:

• ‍Fatigue or tiredness: This is often most noticeable when you first start taking the medication.‍
• Dizziness or lightheadedness: This can be a sign of a slow heart rate or low blood pressure.‍
• Cold hands and feet: Beta-Blockers can affect blood flow to your extremities.
• ‍Weight gain: Some people may experience a small amount of weight gain.

If you notice side effects that don’t go away or feel uncomfortable, it’s a good idea to keep track of how you’re feeling and look into other options. Sometimes small changes or trying something different can make a big difference.

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Important Considerations

Before starting a Beta-Blocker, be sure to tell your doctor about:

• ‍Any other medications you are taking: This includes over-the-counter drugs and supplements.‍
• Any other medical conditions you have: Especially asthma, as some Beta- Blockers can make asthma symptoms worse.‍
• If you are pregnant or planning to become pregnant.

It’s always best to ease off Beta-Blockers gradually, rather than stopping all at once. Stopping suddenly can cause your heart rate and blood pressure to spike, which isn’t safe. If you ever feel unsure about continuing, it’s a good idea to look into the safest way to make changes.

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Conclusion

That wraps up our quick guide on how Beta-Blockers can affect your ECG. We hope it gave you a bit more clarity and peace of mind.

If you’re still feeling unsure about what you’re seeing on your ECGs, you’re not alone. Starting or adjusting to a new medication can be confusing, especially when it comes to your heart. That’s exactly why we created the Qaly app. With Qaly, human experts review your ECGs in minutes, helping you understand how your heart rhythm may be changing and giving you confidence in your care.

To get started, download the Qaly app from the App Store or Play Store. And if you have any questions along the way, feel free to reach out to us at support@qaly.co.

As always, stay heart healthy ❤️