Slow heartbeat: is bradycardia dangerous and when is a pacemaker needed?

If your resting heart rate is below 60 beats per minute, this is called bradycardia. During sleep or in very fit people, such a pulse may be normal. So do not worry because of the number alone: the doctor assesses it together with how you feel and your test results.

The ESC and EHRA AFib Matters website recommends seeing a doctor if heart rhythm symptoms come with dizziness, chest pain or shortness of breath. If you have such signs with a slow pulse, do not put off seeing a doctor.

According to the ACC summary of the 2021 ESC/EHRA guideline, when bradycardia is suspected, testing goes step by step:

• the doctor asks you careful questions and examines you;
• if there are symptoms, heart imaging tests: the heart's structure, left ventricular function and causes that can be corrected are looked at;
• if symptoms appear during exertion or right after it, an exercise test is done;
• if there are signs of breathing pauses during sleep (apnea), or if a very slow pulse during sleep or a high-degree atrioventricular (AV) block is found, apnea is tested for;
• in rare fainting of unknown cause, an implantable loop recorder may be used.

This list does not mean that everyone needs all of it: the doctor decides what to choose.

According to AFib Matters, checking your pulse by hand helps to suspect a rhythm disorder, but it cannot reliably confirm it. The key is an ECG taken during symptoms.

Which method is chosen depends on how often the symptoms occur. According to the ambulatory ECG monitoring guideline of British Columbia (Canada):

• if symptoms occur on most days, 24–48-hour Holter monitoring;
• for less frequent and unpredictable symptoms, an external event or loop recorder (up to about one month);
• for symptoms less than once a month, an implantable loop recorder (up to about 3 years; this is an invasive method).

If symptoms are rare, repeating the Holter may not help. And if event monitoring is arbitrarily limited to one month, the arrhythmia may also be missed.

Not everyone found to have bradycardia needs a pacemaker. According to the ACC summary of the 2021 ESC/EHRA guideline, for example, congenital heart block without symptoms may not require a pacemaker if there are no risk signs.

The decision is made together: the evidence, your individual risk and benefit, your wishes and the goals of treatment are taken into account. In severe recurrent fainting, dual-chamber pacing may reduce recurrences in some patients older than 40 with recorded pauses; in fainting caused by bradycardia or heart block, the decision is different and is made by a specialist. The doctor assesses the exact criteria for your situation.

According to the guideline, the risk of infection is higher in procedures to replace or upgrade a pacemaker. If there is no access through a vein or the risk of infection is high, a leadless pacemaker may be considered. The doctor decides which option suits you.

This article does not give information on the details of the procedure, battery life, MRI and driving rules. Discuss these questions with your treating doctor or an arrhythmologist. There is also an EHRA patient website for people with implanted devices, called myrhythmdevice.org.

According to AFib Matters, heart rhythm episodes that come with shortness of breath, dizziness, fainting or chest pain require urgent medical help.

Before seeing your doctor, keep a symptom diary: how long the symptoms last, what triggers them and what other signs come with them. What you can ask your doctor:

• What is causing my slow pulse?
• Which tests have been done, and what else is needed?
• Do I need a pacemaker, or is there another way?