Heart Arrhythmia: Symptoms, Types, and When It's Dangerous

The heart beats around 100,000 times a day — and most of the time we don't notice it at all. But sometimes a person suddenly feels their heart "skip a beat", race, or slow down unexpectedly. This is arrhythmia — a disruption of the heart's normal rhythm. According to the WHO, arrhythmias affect one in five adults over the age of 40. Most are harmless, but some require urgent treatment. This article explains how to tell the difference.

What arrhythmia is and why it happens

Normally, the heart beats rhythmically: 60 to 100 times per minute at rest. The impulse originates in the sinus node — a small cluster of cells in the right atrium — and travels through the heart's conduction system, causing its chambers to contract in the correct sequence.

Arrhythmia occurs when something disrupts this process: the impulse fires too often or too rarely, originates in the wrong place, or travels through the heart with a delay. Causes include:

• coronary artery disease and previous heart attack;
• arterial hypertension;
• heart valve disease (congenital or acquired);
• electrolyte imbalances — low potassium, magnesium, or calcium;
• thyroid disorders (especially hyperthyroidism);
• excess caffeine, alcohol, or energy drinks;
• certain medications (antidepressants, fluoroquinolone antibiotics, and others);
• chronic sleep deprivation and severe stress;
• in young people — often autonomic dysfunction without structural heart disease.

It's important to understand: arrhythmia is a symptom, not a standalone diagnosis. There is always an underlying cause that needs to be identified.

Types of arrhythmia: tachycardia, bradycardia, fibrillation

Arrhythmias are classified by heart rate, origin, and mechanism. Here are the most common types patients encounter.

Sinus tachycardia — heart rate above 100 beats per minute with a normal contraction sequence. Most often a normal response to exercise, stress, fever, dehydration, or anaemia. Pathological sinus tachycardia at rest warrants investigation.

Sinus bradycardia — heart rate below 60 beats per minute. In athletes, this is normal (a resting pulse of 40–50 is a sign of a well-trained heart). Pathological bradycardia occurs with hypothyroidism, beta-blocker use, or sick sinus syndrome. A pulse below 40 with symptoms requires urgent assessment.

Ectopic beats (extrasystoles) — premature heartbeats. Felt as a "thud", "flutter", or "pause" in the chest. Occasional ectopic beats occur in almost all healthy people and are harmless. Frequent ones (more than 10,000 per day on Holter monitoring) or runs of beats require cardiological evaluation.

Atrial fibrillation (AF) — the most common serious arrhythmia. The atria stop contracting rhythmically and begin "quivering" at 350–600 impulses per minute. The ventricles beat chaotically — usually 80–160 times per minute. AF increases stroke risk fivefold and always requires treatment. It affects 1–2% of the population, with prevalence rising sharply with age: after 80, one in ten people is affected.

Paroxysmal supraventricular tachycardia (SVT) — sudden episodes of rapid heart rate at 150–250 beats per minute that stop just as abruptly. More common in young people, often without structural heart disease.

Ventricular tachycardia and ventricular fibrillation — the most dangerous arrhythmias. Ventricular fibrillation is cardiac arrest and requires immediate resuscitation.

Symptoms that require urgent medical attention

Many arrhythmias are asymptomatic or cause only mild discomfort. But certain signs cannot wait:

• Loss of consciousness or near-fainting — especially if sudden and without warning. May indicate a dangerous ventricular arrhythmia or complete heart block.
• Chest pain or pressure alongside a rapid pulse — possible heart attack or unstable angina.
• Breathlessness at rest combined with arrhythmia — a sign of heart failure.
• Pulse below 40 or above 150 beats per minute at rest with symptoms (weakness, dizziness, visual darkening).
• Sudden slurred speech or limb weakness in the setting of atrial fibrillation — possible stroke; call emergency services immediately.

If you're experiencing heart rhythm disturbances, try describing your symptoms to our assistant — this helps organise your complaints before a doctor's visit.

Holter monitoring: when and why

A standard ECG is recorded in 10–15 seconds and only captures what is happening at that moment. If an arrhythmia occurs intermittently, it may not appear on a routine ECG. This is why Holter monitoring exists — continuous ECG recording over 24–48 hours (sometimes up to 7 days) during normal daily activities.

Holter monitoring is indicated when:

• there are complaints of palpitations but the routine ECG is normal;
• there have been unexplained episodes of loss of consciousness or near-fainting;
• the effectiveness of antiarrhythmic treatment needs to be assessed;
• the doctor wants to count the number of ectopic beats per day;
• nocturnal sleep apnoea with arrhythmias is suspected.

During Holter monitoring, it's important to keep a diary: recording the time of physical activity, stress, meals, and — most importantly — the moment you feel symptoms. This helps the doctor correlate the recording with your experience.

In addition to Holter monitoring, arrhythmia workup may include: echocardiography (cardiac ultrasound) to assess heart structure and function; blood tests — TSH (thyroid), electrolytes (potassium, magnesium), full blood count; stress tests (bicycle ergometry, treadmill) if arrhythmia occurs during exertion.

Arrhythmia and lifestyle

Many arrhythmias are sensitive to lifestyle factors. Here is what genuinely helps:

• Sleep. Sleep deprivation (less than 7 hours) and obstructive sleep apnoea are proven triggers for atrial fibrillation. Treating apnoea reduces recurrence rates.
• Alcohol. Even moderate alcohol consumption increases AF risk. The "holiday heart" effect — atrial fibrillation appearing after a drinking episode — is well documented in cardiology.
• Caffeine. Moderate coffee intake (up to 3 cups per day) does not increase arrhythmia risk in most people. But in sensitive individuals and with energy drink overuse, caffeine triggers ectopic beats and tachycardia.
• Physical activity. Regular moderate exercise reduces the risk of most arrhythmias. Extreme endurance sports (marathons, ultra-triathlons) may increase AF risk in predisposed individuals.
• Electrolytes. Potassium and magnesium deficiency are common causes of ectopic beats. Normal blood potassium: 3.5–5.0 mmol/L; magnesium: 0.7–1.0 mmol/L.
• Stress. Chronic stress activates the sympathetic nervous system, triggering tachycardia and ectopic beats. Stress management techniques (meditation, breathing exercises) have demonstrated benefit.

If you're unsure which specialist to see for heart rhythm complaints, use the doctor routing tool.

Frequently asked questions

Are ectopic beats dangerous?

In most cases, no. Occasional ectopic beats occur in healthy people and require no treatment. The risk increases with frequent ventricular ectopics (more than 10,000 per day), runs of beats, or underlying structural heart disease. Holter monitoring and echocardiography help assess this.

Can I exercise with arrhythmia?

It depends on the type. With functional ectopic beats and sinus tachycardia, moderate exercise is usually permitted. With atrial fibrillation, ventricular tachycardias, or structural heart disease, exercise intensity is agreed with a cardiologist individually.

What is atrial fibrillation and why is it dangerous?

Atrial fibrillation is chaotic quivering of the atria. It is dangerous because blood clots can form in the atria and travel to the brain, causing stroke. Stroke risk with AF is five times higher than without it. This is why most patients are prescribed anticoagulants (blood-thinning medication).

Does asymptomatic arrhythmia need treatment?

It depends on the type. Asymptomatic atrial fibrillation still requires treatment because of stroke risk. Asymptomatic isolated ectopic beats generally do not. The decision is made by a cardiologist after full evaluation.

What should I do during a sudden episode of rapid heartbeat?

Sit or lie down and try to stay calm. You can try vagal manoeuvres: hold your breath and bear down (Valsalva manoeuvre), or splash cold water on your face. If your pulse is above 150 beats per minute, or there is chest pain, breathlessness, or dizziness — call emergency services. If episodes recur, see a cardiologist for evaluation.

Which doctor treats arrhythmia?

Initial assessment is done by a GP or cardiologist. For complex arrhythmias requiring invasive treatment (ablation, pacemaker implantation), referral to an electrophysiologist — a cardiologist specialising in heart rhythm disorders — is made.

Symptomatica is an informational reference service. Not a medical service; does not diagnose or prescribe treatment. For any symptoms, please consult a doctor.

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