Chronotropic Incompetence

What is chronotropic incompetence?

Chronotropic incompetence (CI) is being unable to increase your heart rate with physical activity. Your body needs more oxygen when you’re moving compared to when you’re not moving. Chronotropic incompetence means your heart can’t keep up with your body’s increased demand for oxygen. With CI, your heart can’t pump enough blood (which carries oxygen) to meet your needs.

CI can lead to exercise intolerance. This means you can’t do as much physical activity as someone your age. You may find it’s harder to walk as far as you once did without feeling like you need to catch your breath.

What are the signs of chronotropic incompetence?

Chronotropic incompetence symptoms include:

• Fatigue during physical activity
• Shortness of breath (dyspnea) from physical activity

What causes chronotropic incompetence?

Causes of chronotropic incompetence include:

• Certain medications, like beta-blockers
• Sinus node dysfunction. This is a problem with the place where your heartbeat starts
• Conduction issues (how heartbeat signals move through your heart)
• Left ventricular dysfunction. This is a problem with the heart chamber that pushes blood out of your heart so your body can use it
• Ischemic heart disease. This happens when blood flow to your heart is too low
• Heart failure. This inability of your heart to pump well leads to fluid buildup
• Congenital heart disease. This includes heart issues that are present at birth

What are the risk factors?

Risk factors for chronotropic incompetence include:

• Heart failure
• Obesity
• Diabetes
• Chronic obstructive pulmonary disease (COPD)
• High blood pressure
• HIV
• Epstein-Barr virus
• Long COVID

How is it diagnosed?

Healthcare providers may make a chronotropic incompetence diagnosis if your heart rate can’t reach a certain level.

Some providers set the goal at 70% to 85% of your age-predicted maximal heart rate (APMHR) during peak physical activity. A common formula for APMHR is 220 minus your age. But providers don’t have a standard they agree on for making a diagnosis. They may use other formulas for diagnosis, like setting the cutoff at 80% of your heart rate reserve. If your heart rate can’t reach 80% of your heart rate reserve, you may have CI.

How do you test for chronotropic competence?

A provider may order a continuous heart rhythm monitor for you to wear so they can see what happens to your heart rate when you’re doing your usual activities. A provider may also perform an exercise EKG or a metabolic exercise stress test, which they also call a cardiopulmonary exercise test (CPET). You’ll walk on a treadmill or pedal on a stationary bike. A provider will measure your heart rate to see if you’re able to increase it to the goal rate they set. For CPET, you’ll also wear a mask to measure the amount of oxygen your body uses when you exercise.

How do you treat chronotropic insufficiency?

Chronotropic incompetence treatment may include:

• Physical activity. This can improve your ability to move more
• Pacemaker. This can ensure your heart rate increases enough to meet your body’s needs when you exert yourself
• Biventricular pacemaker (also called cardiac resynchronization therapy). This is a special pacemaker that makes sure your two lower heart chambers beat together. This type of pacemaker benefits specific heart conditions

Can chronotropic incompetence be prevented?

Some of the conditions that cause chronotropic incompetence are beyond your control. But you can reduce your risk of CI in several ways, like:

• Getting treatment for any heart or lung condition you have
• Staying at a weight that’s healthy for you
• Managing conditions like diabetes and high blood pressure

What can I expect if I have chronotropic incompetence?

Adults with chronotropic incompetence may have more fatigue or breathlessness than expected during usual daily activities or physical activity. Rare cases may lead to fainting when your heart rate isn’t fast enough to supply enough blood to your brain.

Studies have shown that adults who have obesity and chronotropic incompetence have a higher risk of heart attack or heart failure. One study suggests that people with CI have a higher risk of developing atrial fibrillation (Afib). CI in people with heart failure is related to poorer overall survival. Studies have also shown an association between chronotropic incompetence and decreased longevity.

How do I take care of myself?

Living with chronotropic incompetence means your body is putting limits on what you can do. This is a time for patience. Talk to your provider about whether you need to change certain medications or whether a pacemaker is appropriate. If your provider inserted a device in your chest, make sure you understand how it works. Keep your follow-up appointments to ensure your device is working properly. If your provider gave you a plan to build up your physical activity, follow the instructions they gave you.

What questions should I ask my healthcare provider?

Questions to consider asking your provider may include:

• Do you know what caused my chronotropic incompetence?
• What can I do to be at my best?
• What can I expect from the pacemaker you put in?
• Are there any programs that can help me do more physical activity?