When your heart starts racing: is it dangerous and what should you do?

In medicine this sensation is called palpitations, that is, feeling your heartbeat: the heart seems to beat harder, faster or more irregularly than usual. According to AFib Matters, a website prepared for patients by the European Society of Cardiology (ESC) and EHRA, this sensation may be a normal state after exercise, excitement or an infection. However, it may also be a sign of an arrhythmia, that is, a heart rhythm disorder. It is hard to tell them apart by the sensation alone; a clear answer comes from tests, usually an ECG taken while the heart is racing.

According to the AFib Matters list, the causes are:

• a normal state after exercise, excitement or an infection;
• extra (ectopic) beats;
• other arrhythmias;
• anxiety, caffeine and other conditions not related to the heart.

Alcohol and caffeine may also be triggers. If the heart beats more than 100 times per minute at rest, this is called tachycardia (a general medical definition). Only an examination and tests can tell what the cause is in your particular case.

When the racing starts:

• sit or lie down and try to calm down;
• write down the time it started and ended;
• pay attention to accompanying signs: dizziness, chest pain, shortness of breath;
• make a note of any coffee or alcohol you drank.

AFib Matters recommends keeping a symptom diary before seeing a doctor: duration, triggers and accompanying signs. Counting your pulse may show that the heart is beating fast, but it cannot reliably confirm an irregular rhythm, especially when the heart is beating fast.

According to AFib Matters, seeing a doctor is needed especially when it comes together with dizziness, chest pain or shortness of breath. Fast episodes that interfere with daily life, as well as episodes with shortness of breath, dizziness, fainting or chest pain, require urgent medical help.

If the racing heart keeps coming back, book a planned appointment with a doctor, even if it goes away on its own. You cannot set a dangerous limit yourself based on the number of beats or the duration: the doctor will tell you this after an examination.

According to AFib Matters, if the heart races all the time, an ECG at rest helps make the diagnosis. If episodes come and go, the main thing is a recording taken during the symptoms. According to the BC Guidelines, the method depends on how often the symptoms occur:

• if almost every day, 24–48 hour Holter monitoring;
• if less often and unpredictable, an external event recorder that you switch on during symptoms, for up to about a month;
• if less than once a month, a small loop recorder placed under the skin, for up to about 3 years; this is an invasive method.

The doctor decides which method suits you.

Some episodes start suddenly and stop suddenly. This may be typical of arrhythmias such as supraventricular tachycardia (SVT) (general medical information). According to the ACC summary of the 2019 ESC guidelines, in all re-entry arrhythmias and in most focal arrhythmias, ablation should be offered as the first option after a detailed discussion of the risks and benefits. This does not mean that everyone needs ablation; the decision is up to the doctor.

In the 2015 REVERT trial (ACEP Now summary), a modified Valsalva maneuver, that is, lying back and raising the legs after straining, restored a normal rhythm at one minute in 43 % of cases, compared with 17 % for the standard maneuver. The trial used a special device and an adjustable bed. Use this maneuver only after a doctor has confirmed supraventricular tachycardia and taught you how to do it; if you have chest pain or feel close to fainting, do not use it at all.