Irregular Heartbeat (Arrhythmia)

What an irregular heartbeat feels like

• a skipped beat, followed by a hard thump
• fluttering or flip-flopping in the chest
• racing or pounding, sometimes felt in the neck
• an uneven, chaotic pulse
• lightheadedness, breathlessness or fatigue
• no symptoms at all, with the rhythm found on a check-up or smartwatch

The awareness of your heartbeat is called palpitations. Not all palpitations are irregular, and not all arrhythmias cause palpitations.

Types of irregular heartbeat

Sinus arrhythmia, where the heart rate speeds up as you breathe in and slows as you breathe out, is normal, especially in children and young adults.

Causes of irregular heartbeat

Lifestyle triggers

• caffeine, energy drinks and nicotine
• alcohol, especially binge drinking ("holiday heart")
• stress, anxiety and panic attacks
• lack of sleep and dehydration
• intense exercise
• recreational drugs such as cocaine and amphetamines

Medicines

Decongestants (pseudoephedrine), asthma inhalers, thyroid hormone at high doses, some antidepressants, antipsychotics, certain antibiotics (macrolides, fluoroquinolones) and anti-nausea drugs that prolong the QT interval.

Medical conditions

• Heart disease: coronary artery disease, previous heart attack, heart failure, cardiomyopathy, valve disease and congenital heart defects.
• High blood pressure, which enlarges the upper chambers and is a major risk factor for atrial fibrillation.
• Overactive thyroid: fast heart rate and atrial fibrillation.
• Sleep apnea: strongly linked to atrial fibrillation.
• Electrolyte imbalances: low or high potassium, low magnesium, high or low calcium.
• Anemia, fever, infection and pregnancy, which raise the heart rate.
• Lung disease and pulmonary embolism.
• Aging: the heart's electrical system wears, causing atrial fibrillation and conduction block.

Inherited rhythm disorders

Long QT syndrome, Brugada syndrome, hypertrophic cardiomyopathy and Wolff-Parkinson-White syndrome can cause dangerous rhythms in young people. Warning signs include fainting during exercise or emotion, and a family history of unexplained sudden death.

How to check your pulse

Place two fingers on the thumb side of your wrist or the side of your neck. Count for a full 60 seconds and note whether the beats are evenly spaced. A normal resting rate is 60 to 100, though fit people may be lower. An irregularly irregular pulse, with no pattern, suggests atrial fibrillation. Smartwatches and home ECG devices can record a rhythm strip to show your doctor, but they can give false alarms and miss some arrhythmias.

When to worry about an irregular heartbeat

Be more concerned if the irregular heartbeat:

• comes with chest pain, breathlessness, fainting or near-fainting
• happens during exercise
• is persistently fast (over 120) or slow (under 40) at rest
• lasts more than a few minutes, or is new and constant
• occurs in someone with known heart disease or a family history of sudden death

Brief, occasional skipped beats in a healthy person without these features are very common and rarely dangerous.

How doctors diagnose arrhythmias

1. History and examination, including triggers, medicines, alcohol, caffeine and family history.
2. ECG (electrocardiogram): a 10-second recording that diagnoses the rhythm if it is happening at the time.
3. Ambulatory monitoring: a Holter monitor for 24 to 48 hours, a patch for up to 2 weeks, an event recorder, or an implantable loop recorder for up to 3 years for rare episodes.
4. Blood tests: thyroid function, electrolytes, blood count, kidney function.
5. Echocardiogram: checks the heart's structure and pumping.
6. Exercise stress test: for symptoms with exertion.
7. Electrophysiology study: catheters map the heart's electrical system, often combined with treatment.

Treatment

Treatment depends on the type and cause:

• Harmless extra beats: reassurance and reducing triggers. Beta blockers if symptoms are troublesome.
• Atrial fibrillation: blood thinners to prevent stroke based on a risk score, medicines to control heart rate or rhythm, cardioversion, and catheter ablation. Treating sleep apnea, high blood pressure, obesity and alcohol use improves outcomes.
• SVT: vagal maneuvers (such as bearing down as if straining), medicines, or catheter ablation, which cures most cases.
• Slow rhythms: stopping medicines that slow the heart, or a pacemaker.
• Dangerous ventricular rhythms: medicines, ablation, or an implantable cardioverter-defibrillator (ICD).
• Underlying causes: treating thyroid disease, correcting electrolytes, and managing heart disease.

Lifestyle measures

• Limit caffeine and alcohol, and avoid energy drinks and recreational drugs.
• Stop smoking.
• Keep blood pressure and weight in a healthy range.
• Sleep 7 to 9 hours and get tested for sleep apnea if you snore heavily.
• Manage stress with regular exercise, breathing techniques or therapy.

Frequently asked questions

What causes an irregular heartbeat?

Common triggers are caffeine, alcohol, stress, lack of sleep, nicotine and some medicines. Medical causes include high blood pressure, heart disease, an overactive thyroid, sleep apnea, electrolyte imbalances and aging of the heart's electrical system. Some rhythm disorders are inherited.

When should I worry about an irregular heartbeat?

Seek emergency care if it comes with chest pain, shortness of breath, fainting or dizziness. See a doctor soon if it is persistent, frequent, fast at rest, happens during exercise, or you have heart disease or a family history of sudden death.

Is an irregular heartbeat dangerous?

Often not. Occasional extra beats are very common and usually harmless. Atrial fibrillation increases the risk of stroke and heart failure, and some ventricular rhythms can be life-threatening. An ECG and monitoring show which type you have.

What does atrial fibrillation feel like?

Many people feel a fast, irregular fluttering or pounding, breathlessness, tiredness, dizziness or reduced exercise tolerance. Some feel nothing and only find out from a check-up or smartwatch. The pulse is irregular with no pattern.

Can anxiety cause an irregular heartbeat?

Anxiety commonly causes a fast heartbeat and can trigger extra beats, which feel like skips or thumps. It does not usually cause sustained arrhythmias like atrial fibrillation. New or persistent irregular heartbeats should be checked with an ECG before they are put down to anxiety.