Some people experience irregular heartbeats because the electrical system that controls the heart’s rhythm is disrupted, either occasionally or persistently. In many cases the cause is entirely harmless, such as the extra beats that almost everyone has from time to time, or the effects of caffeine, alcohol, stress or tiredness. In others, an irregular heartbeat reflects an underlying rhythm disorder such as atrial fibrillation, which needs proper assessment because, untreated, it can raise the risk of stroke. The difficulty is that these two situations can feel very similar, which is why irregular heartbeats deserve to be checked rather than guessed at.
The heart’s rhythm is controlled by a precise electrical circuit, and irregular heartbeats happen when that circuit misfires, speeds up, slows down or is interrupted. Over more than 20 years as a Consultant Cardiologist at Kingston Hospital, much of that as Clinical Lead of the department, and with a longstanding specialist interest in echocardiography and rhythm assessment across my private clinics at Parkside, The New Victoria, Cleveland Clinic London and Heartsure, I would estimate that a clear majority of the patients referred to me with irregular heartbeats turn out to have a benign cause. The purpose of assessment is not to alarm anyone. It is to identify the minority who need treatment, and to reassure the majority who do not.
How a normal heartbeat works
To understand why a heartbeat becomes irregular, it helps to know how the rhythm is normally kept steady. Each beat begins in a small cluster of cells in the top right chamber of the heart called the sinus node, which acts as the heart’s natural pacemaker. It sends out an electrical signal that spreads across the upper chambers, causing them to contract, then passes through a junction box called the AV node into the lower chambers, which contract in turn to pump blood to the body.
When this sequence runs smoothly, the heart beats regularly at a rate appropriate to what you are doing. An irregular heartbeat occurs when something disrupts this process, whether an extra signal firing from the wrong place, a short circuit in the wiring, a blockage in the pathway, or an outside influence altering how the whole system behaves. The BHF overview of heart rhythm problems sets out this electrical anatomy in accessible terms.
The harmless causes that account for most cases
The most common reason people feel an irregular heartbeat is ectopic beats, which are extra beats that arrive slightly early and are followed by a small pause. Almost everyone has them, and they are usually felt as a skipped beat, a thud, or a flip in the chest. In the great majority of people they are entirely benign and need no treatment at all.
A range of everyday factors provoke these extra beats and other minor irregularities. Caffeine, alcohol, nicotine, tiredness, dehydration, stress and strong emotion all commonly trigger them, as does the period after a large meal. What I have found across many years of assessing these symptoms is that identifying a patient’s personal triggers works better than reaching for medication in most cases of benign ectopic beats, because once someone understands that their skipped beats reliably follow their third coffee or a poor night’s sleep, the symptom becomes far less frightening and often far less frequent. Alcohol in particular is a common and underestimated culprit, and the wider impact of alcohol on heart health extends well beyond rhythm alone.
Atrial fibrillation, the one that matters most
The irregular heartbeat cardiologists are most concerned to identify is atrial fibrillation, the most common sustained rhythm disorder. Here the upper chambers of the heart, instead of contracting in an organised way, quiver chaotically, producing a heartbeat that is irregular in both timing and force. It is often felt as a fast, erratic fluttering, though some people feel nothing at all and are only diagnosed by chance.
Atrial fibrillation matters because it allows blood to pool and clot in the upper chambers, and if a clot travels to the brain it causes a stroke. This is why detecting it is so important, and why treatment often involves anticoagulation to reduce that risk alongside measures to control the rhythm or rate. The condition becomes more common with age and is strongly linked to high blood pressure, alcohol, obesity and sleep apnoea. Drawing on the patients I have assessed for this condition over the years, catching atrial fibrillation early works better than waiting for it to declare itself through a complication, because the first sign of undiagnosed atrial fibrillation is too often a stroke that could have been prevented had the rhythm been picked up sooner.
The other rhythm disorders I see
Beyond ectopic beats and atrial fibrillation, several other rhythm disturbances can cause an irregular or abnormal heartbeat. Supraventricular tachycardia produces sudden episodes of a very fast, regular heartbeat that starts and stops abruptly, often in younger people with otherwise healthy hearts. Atrial flutter is related to atrial fibrillation but produces a more organised fast rhythm. Heart block, at the other end of the spectrum, is a slowing or interruption of the electrical signal as it passes to the lower chambers, which can cause a slow pulse, dizziness or blackouts.
More rarely, irregular heartbeats arise from the lower chambers of the heart, and these ventricular rhythms can be more serious, particularly in someone with underlying heart disease. This is part of why an irregular heartbeat in a person with known coronary disease or a weakened heart muscle is treated with more caution than the same symptom in an otherwise healthy young person. The context in which the rhythm occurs matters as much as the rhythm itself.
The underlying conditions that disturb rhythm
Sometimes an irregular heartbeat is a symptom of something else affecting the heart or the body more widely. An overactive thyroid is a classic cause and is easily missed without a blood test. High blood pressure strains and stretches the heart over time, making rhythm problems more likely, and coronary artery disease can disturb the electrical system where it has affected the heart muscle. Heart valve problems and a weakened heart muscle both predispose to irregular rhythms as well.
Sleep is another significant and frequently overlooked factor. Untreated sleep apnoea is strongly associated with atrial fibrillation, and treating it can reduce the frequency of episodes considerably. The connection between rest and rhythm runs deep, and the broader relationship between poor sleep and heart problems is worth understanding for anyone who snores heavily or wakes unrefreshed. Electrolyte imbalances, certain medications and some recreational drugs round out the list of causes I routinely consider.
The symptoms that should prompt assessment
Not every irregular heartbeat needs urgent attention, but certain features raise the priority. An irregular heartbeat that is sustained rather than a fleeting skipped beat, that is associated with breathlessness, chest discomfort, dizziness or fainting, or that comes with a very fast or very slow pulse, all warrant proper evaluation. So does an irregular heartbeat in someone with known heart disease or a family history of sudden cardiac death.
The pattern also matters. Episodes that start and stop abruptly, that last a long time, or that are becoming more frequent are more likely to represent a defined rhythm disorder than isolated extra beats. What I emphasise to patients is that the feeling alone cannot reliably distinguish a harmless cause from one that needs treatment, which is exactly why capturing the rhythm on a recording is so valuable.
How I assess irregular heartbeats in clinic
The central challenge with irregular heartbeats is that they often come and go, so the aim of assessment is to record the heart’s electrical activity during a symptom. It usually begins with a resting ECG, though this only captures a brief moment and will often look normal if the patient is not having symptoms at that time. Blood tests to check thyroid function and electrolytes are routine, and an echocardiogram assesses whether there is any structural cause within the heart.
The key to diagnosis is usually prolonged monitoring, and this is where the choice of test matters. A 24-hour or 48-hour monitor is useful for frequent symptoms, but for episodes that occur only every week or two it will often miss them entirely. Drawing on the many rhythm assessments I have arranged, a ZIO patch worn for up to 14 days works better than a standard 24-hour monitor for intermittent symptoms, because the longer recording window dramatically increases the chance of capturing an episode that would otherwise slip through a shorter test. For very infrequent but significant symptoms, longer-term monitors or implanted recorders occasionally have a role. Catching the rhythm during a symptom is what turns uncertainty into a clear diagnosis and a clear plan.
When irregular heartbeats need treatment
Treatment depends entirely on the cause. Benign ectopic beats usually need nothing more than reassurance and attention to triggers such as caffeine, alcohol and sleep. Atrial fibrillation is treated with a combination of measures to control the rate or rhythm and, in most patients, anticoagulation to reduce stroke risk. Supraventricular tachycardias and atrial flutter often respond very well to catheter ablation, a procedure that targets the small area of tissue responsible for the abnormal circuit, and for these patients I work closely with my colleague Dr Para Dhillon. Heart block that is causing symptoms may require a pacemaker.
The reassuring reality is that most rhythm disorders are highly treatable once identified, and many can be resolved completely. The priority is always to make the correct diagnosis first, because the right treatment for one rhythm disorder can be entirely wrong for another.
When to seek a cardiology opinion
A specialist assessment is worth arranging if you have irregular heartbeats that are frequent, sustained or worsening, or that come with breathlessness, chest discomfort, dizziness or fainting. It is also worth arranging if you have been told you have an irregular pulse, if you have a family history of rhythm problems or sudden cardiac death, or if you have risk factors such as high blood pressure or heavy alcohol use alongside palpitations. Anyone who has had a blackout with an irregular heartbeat should be assessed promptly rather than waiting.
You can read verified feedback from patients I’ve seen if it helps you decide whether a private cardiology opinion is the right step for you.
Conclusion
Irregular heartbeats are extremely common, and in the majority of people they are harmless, driven by nothing more than extra beats and everyday triggers such as caffeine, alcohol, stress and tiredness. In a minority, they signal a defined rhythm disorder such as atrial fibrillation, which is important to identify because effective treatment can prevent serious complications including stroke. Because the harmless and the significant can feel so alike, the sensible approach is not to worry alone or to dismiss the symptom, but to have the rhythm properly recorded so that you know exactly what you are dealing with.
If you are experiencing irregular heartbeats, or you have been told your pulse is irregular, you can contact me, Dr Arvind Vasudeva, on 020 8977 4826 to arrange a rhythm assessment. I consult at Parkside Hospital in Wimbledon, The New Victoria Hospital in Kingston, Cleveland Clinic London and the Heartsure Clinic, and you can book a convenient appointment here through my secretary Hannah.