Premature heartbeats (extrasystoles)

What extrasystoles are

The normal rhythm of the heart is set by a group of specialized cells in the right atrium, the sinus node, which produces an electrical impulse about 60–100 times a minute at rest. The impulse spreads through the atria and then the ventricles and makes the heart contract in a regular way.

An extrasystole is a beat that arrives ahead of time, because a group of cells outside the sinus node fires an early impulse. By where the impulse starts, we distinguish:

• Atrial extrasystoles (premature atrial contractions, PACs): they start in the atria;
• Ventricular extrasystoles (premature ventricular contractions, PVCs): they start in the ventricles, the chambers that pump blood to the body and lungs.

Both types are common even in completely healthy people and can occur at any age, although they become more frequent with years. They are not the same as a sustained arrhythmia such as atrial fibrillation: extrasystoles are isolated beats, while arrhythmias are prolonged rhythms.

How they feel, and why the “skip” happens

Many people feel nothing, and extrasystoles are found by chance on an ECG or when the pulse is checked. When they are felt, they are described as:

• the sensation that the heart “skips” or “stops” for a moment;
• a “hard beat”, thump or flutter in the chest or throat;
• a delayed beat followed by a strong one;
• sometimes, a feeling of relief or brief tiredness after the episode.

There is an explanation for this. After the premature beat the heart usually takes a small pause, because the electrical system needs to reset. During the pause the ventricle fills with more blood than usual, so the next beat is stronger. What we feel is not the “missing beat” but the strong beat that follows it. The premature beat itself is often so weak that we do not feel it, and it may not even register as a pulse at the wrist.

Extrasystoles are felt most when you are calm, lying down or before sleep, because nothing else competes for your attention. In some people they disappear during exercise, when the heart beats faster.

What triggers them

In most cases no single cause is found, but several factors increase how often they occur:

• Stress, anxiety, tiredness and lack of sleep, which raise sympathetic nervous system activity;
• Caffeine (coffee, tea, energy drinks), nicotine and alcohol;
• some medicines: decongestants (such as pseudoephedrine), some bronchodilators and diet pills, and stimulant drugs;
• electrolyte disturbances (potassium, magnesium), for example after vomiting, diarrhea or use of diuretics;
• medical conditions: anemia, hyperthyroidism, fever, hypoxia, sleep apnea;
• heart disease: coronary artery disease, a previous heart attack, cardiomyopathies, valve disease, heart failure, uncontrolled high blood pressure;
• after a large meal or with gastroesophageal reflux, because the vagus nerve can irritate the rhythm.

For this reason the assessment does not focus only on the beats, but on the whole picture: symptoms, the medicines you take, habits and the heart itself.

How they are assessed

The cardiologist’s aim is to answer two questions: are these really extrasystoles (and not another arrhythmia), and is there another heart condition that causes them or makes them important.

• History and physical examination: when they occur, how long they last, what triggers them, whether there has been fainting, chest pain or dyspnea; whether there is a family history of sudden death or heart disease; what medicines and stimulating drinks you take.
• A resting ECG can catch extrasystoles if they happen at that moment, but a normal ECG does not exclude them, since the recording lasts only a few seconds.
• Holter ECG (24–48 hours) records the rhythm through day and night and helps count the extrasystoles and see whether they relate to activity or symptoms. For ventricular extrasystoles, the percentage of premature beats out of all beats in a day (the “burden”) is one of the most important measures.
• Echocardiography assesses the structure of the heart, the strength of its contraction and the valves. It matters especially when extrasystoles are frequent or when there are other symptoms.
• Blood tests: hemoglobin, electrolytes (potassium, magnesium), thyroid and kidney function, as needed.
• In selected cases, when further heart disease is suspected or the burden is high, additional tests may be recommended at specialized centers, such as cardiac magnetic resonance imaging or exercise-based tests.

The assessment is often reassuring: in a person without alarming symptoms, with a normal ECG and echocardiogram and with rare extrasystoles, nothing more is needed.

When they are harmless and when they should not be ignored

In a healthy heart, occasional extrasystoles usually do not increase the risk of serious disease and do not need treatment. Reassurance, an explanation of the mechanism and changes in habits are often the most important part of treatment.

There are situations that call for more attention:

• when ventricular extrasystoles are very frequent (premature beats that make up a substantial share of the day’s beats), because in some patients, over time, they can weaken the heart muscle. This is monitored with repeat Holter and echocardiography;
• when they occur in runs (several in a row) or come with fainting, chest pain or dyspnea;
• when there is known heart disease (previous heart attack, cardiomyopathy, heart failure);
• when there is a family history of sudden death at a young age or of inherited cardiomyopathies;
• when frequent atrial extrasystoles come with prolonged regular or irregular episodes, which may be atrial fibrillation.

In these cases the cardiologist may decide on closer follow-up, additional tests or treatment.

How they are treated

Most people do not need medicines. The steps below are listed in order of importance:

1. Remove obvious triggers: cut down on caffeine, alcohol and nicotine, sleep enough, and check whether any medicine you take (prescribed or over the counter) could play a role. Do not stop prescribed medicines without asking your doctor.
2. Treat accompanying conditions: anemia, hyperthyroidism, electrolyte disturbances, sleep apnea, high blood pressure, gastroesophageal reflux, coronary or valve disease.
3. Regular physical activity and relaxation techniques usually help; exercise is not forbidden for most people with isolated extrasystoles, but it should be discussed with the doctor if there is heart disease or fainting.
4. Medicines: when symptoms are bothersome or extrasystoles are very frequent, the doctor may prescribe a beta-blocker or other anti-arrhythmic medicines. They are chosen individually and require medical supervision.
5. Catheter ablation: rarely, when ventricular extrasystoles are very frequent, persist despite medicines or weaken the heart, a procedure that “deactivates” the point where the impulse starts may be proposed. It is carried out by electrophysiologists at specialized centers.

Do not take anti-arrhythmic medicines or potassium supplements on your own; a wrong level of them can be dangerous.

How to prepare for the visit

Keep a short diary for one week: when the sensations occur, how long they last, what you were doing (resting, exercising, after coffee, before sleep) and whether there were other symptoms. It is helpful to check your pulse during an episode, or to record an ECG if you have a suitable device. Bring your list of medicines and supplements, and any previous ECG, Holter or echocardiogram.

Contact the cardiologist without delay if episodes become more frequent, last longer or come with fainting, chest pain or dyspnea.