Extrasystoles (Premature Heartbeats): When They Are Harmless

Extrasystoles are among the most common heart rhythm disturbances. A review of ventricular beats states that they are 'extremely common' and occur in most people undergoing long-term ambulatory monitoring, and that their frequency increases with age, height, higher blood pressure, a history of heart disease, lower physical activity and smoking. It also stresses that the causes of most individual beats remain unknown, and the mechanisms include triggered activity, automaticity and reentry.

This is a good summary of the current state of knowledge: extrasystoles are not a uniform disease but a symptom or a test finding whose significance depends on context. In practice the doctor asks about three things: how many there are (burden), whether the heart has structural disease or impaired function, and whether the patient has symptoms. We describe how these three elements combine into a treatment decision in the sections below.

These numbers must be interpreted very carefully. The study included patients already referred for ablation because of frequent beats, a highly selected group burdened with a large number of beats. The 24% threshold is thus a value that statistically separates the groups in this population, not a limit below which the heart is safe. The value of 10% is the lowest observed in the study at which reversible cardiomyopathy occurred. In people with infrequent beats, on the order of hundreds or a few thousand per day (a few percent of beats), the risk of weakening the heart muscle is much smaller, though not zero, especially with structural disease.

Data from the general population complete the picture: even at a frequency much lower than in people referred for ablation, a higher burden of ventricular beats was associated with a greater risk of worsening heart function and death over long follow-up. This is an observational association in an older group (CHS), in which extrasystoles could also have been a marker of unrecognized heart disease. It therefore does not prove that every beat does harm, nor does it set a practical treatment threshold. It does, however, justify sensible vigilance: assessing the heart when beats are frequent and periodic review if their number is high.

Factors favoring extrasystoles include: stress and strong emotions, short sleep, alcohol, nicotine, excess caffeine and other stimulants, dehydration, fever, intense exertion, and also electrolyte disturbances (low potassium, low magnesium), an overactive thyroid, anemia and some drugs (among them sympathomimetics, bronchodilators, some antidepressants). Add heart diseases: hypertension, coronary disease, valve disease, cardiomyopathies, myocarditis. In practice many people cannot identify a single cause.

The results on caffeine can be surprising to people whom doctors advise against coffee. This observational study in older people did not show a relationship between average consumption and the number of beats on Holter. That does not mean that in a particular person a large dose of caffeine cannot heighten the perception of extrasystoles. Because the response is individual, it makes sense to run your own experiment: cut caffeine for 2–4 weeks and observe whether the awareness of beats decreases. More on caffeine in the knowledge base entry.

The same goes for electrolytes: low potassium and magnesium can favor rhythm disturbances, so in assessing extrasystoles their levels are checked (we describe them in the entries on electrolytes and on magnesium). Replenishing magnesium in a person without a deficiency is not a proven treatment for extrasystoles. It is also worth doing TSH, a blood count and glucose, because an overactive thyroid and anemia are reversible causes.

The basis is the resting ECG, which shows whether the extrasystoles are atrial or ventricular, what shape they have (suggesting the site of origin), and whether the tracing shows features of structural disease, blocks or repolarization disturbances (described in the entry on the resting ECG). To assess the burden, a Holter ECG is needed, usually 24–48 hours and, if the frequency varies, sometimes longer (entry on Holter ECG and ambulatory blood pressure monitoring). The Holter also shows whether the beats occur singly, in pairs (couplets), in runs (non-sustained tachycardia) and at what time of day.

Echocardiography is indicated with symptoms or particularly frequent beats, and also when the history or ECG shows features of heart disease (entry on echocardiography). It assesses the ejection fraction, chamber dimensions, wall thickness and valves. Cardiac magnetic resonance is sometimes helpful when cardiomyopathy, myocarditis or a scar is suspected (for example when beats are multifocal, have an atypical shape or occur in a younger person with a family history). An exercise test shows how the beats behave during exertion: their disappearance with exercise is more often a favorable feature, while an increase calls for more attention (entry on the exercise test).

Blood tests usually include TSH, blood count, electrolytes (potassium, magnesium, calcium) and glucose; as indicated also markers of cardiac injury (entry on troponin and NT-proBNP). The scope of tests depends on symptoms, age, family history and initial results. For many people with infrequent, asymptomatic beats, a normal ECG and the knowledge that the heart is healthy, a conversation and reassurance are enough. In people with frequent ventricular beats or symptoms the assessment is broader.

Supraventricular (atrial) extrasystoles are common and usually harmless, but not entirely neutral. In a meta-analysis of 11 high-quality studies, frequent atrial beats were associated with a higher risk of stroke (adjusted RR 1.41; 95% CI 1.25–1.60) and death from any cause (adjusted RR 1.26; 95% CI 1.13–1.41), these being observational associations, and the authors stressed the need for further research on optimal management. Atrial beats can be a forerunner or marker of atrial fibrillation, especially in older people and with other risk factors.

For practice this means that in a young, healthy person with infrequent atrial beats there is no cause for concern, whereas in an older person with hypertension, sleep apnea or obesity and a large number of supraventricular beats it is worth talking to a doctor about rhythm monitoring, blood pressure and stroke risk factors. Starting anticoagulants on your own is not recommended, and decisions on stroke prevention in atrial fibrillation are made on the basis of a diagnosed arrhythmia and a risk score.

Most people need no treatment. When extrasystoles are infrequent, the heart is healthy and symptoms are mild, it is enough to explain that they are harmless and to remove favoring factors: limiting alcohol and nicotine, enough sleep, regular exercise, stress reduction, treating an overactive thyroid or anemia, correcting electrolytes. If symptoms are troublesome, beta-blockers or non-dihydropyridine calcium channel blockers (verapamil, diltiazem) are used, and if they fail, other antiarrhythmic drugs chosen by the cardiologist.

Catheter ablation is reserved for selected patients: those with troublesome symptoms not responding to drugs, with drug intolerance, with very frequent beats (especially when there is evidence of worsening left ventricular function) or when the patient prefers a procedure to long-term treatment. It is most effective when the focus is in an easily accessible place such as the right ventricular outflow tract, but it carries procedural risk and is not always possible. Ling's study included a selected group from one location, so the results do not translate directly to every patient. The decision is made by an electrophysiologist together with the patient.

In extrasystoles with existing heart disease (for example after a heart attack, in cardiomyopathy) treatment depends above all on the underlying disease and the risk of dangerous arrhythmias, not on the number of beats alone. The European Society of Cardiology guidelines on ventricular arrhythmias (2022) discuss management in the individual groups in detail; their application is up to the treating physician.

The second myth is the belief that the number of beats on the Holter says everything. The type of beats (atrial or ventricular, single or in runs), their shape, heart function on echo and symptoms matter just as much. Two people with the same number of beats may need completely different management.

For most people extrasystoles are bothersome but harmless, and the most important task is to make sure the heart is healthy: a normal ECG, a multi-day Holter recording with a low burden and a normal echo. If so, the best strategy is often calm observation, reduction of favoring factors and avoiding excessive 'listening' to your own heart. When the burden is high, the beats are atypical or alarm symptoms appear, it is worth seeing a cardiologist, because early treatment can protect the heart muscle from weakening.