Harvard Heart Letter

Ask the doctor: Do beta blockers and ACE inhibitors help or harm the heart?

Ask the doctor

Do beta blockers and ACE inhibitors help or harm the heart?

Q. Is my long-term use of beta blockers and ACE inhibitors setting me up for heart failure? As I understand it, these drugs reduce my heart's pumping power and keep my heart rate low. If the heart is a muscle, and muscles are strengthened by exercise, won't slowing the heart and making it pump with less power weaken it? If that's the case, isn't this a prescription for heart failure?

A. Big muscles may be fine for your arms and legs, but when it comes to your heart, you are much better off with chamber walls that aren't too thick and muscular from pumping against high blood pressure. The arteries that supply the heart with oxygen and nutrients run along the heart's outside wall. Blood flows into the heart muscle via small vessels that penetrate into the muscular walls. The thicker the heart, the more difficult it is for blood to reach the innermost portions of the muscle. By opening up your body's arteries, ACE inhibitors lower blood pressure. This keeps your heart muscle from "bulking up," which helps your heart stay healthier.

As you mentioned, beta blockers slow the heart rate. For many people, that is actually a good thing. Every time the heart contracts, blood flow temporarily stops in the small vessels that supply heart cells with oxygenated blood. It resumes when the heart relaxes. So the faster your heart beats, the less time there is between beats, which makes it harder for blood to flow into the more remote parts of your heart muscle. By slowing the heart rate, beta blockers allow for longer spans of blood flow. These drugs also keep the muscle from wearing out because of too much intense activity.

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