Heart Arrhythmia: Symptoms, Types, Causes, Diagnosis & Treatment — Complete Guide
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
A heart arrhythmia is an irregular heartbeat caused by faulty electrical signals, making the heart beat too fast, too slow or inconsistently. Some are harmless, but ventricular fibrillation is the most frequent cause of sudden cardiac death. Chest pain, shortness of breath or fainting are emergencies, so call 911. Treatment ranges from medicines to ablation, pacemakers and defibrillators.
What the research says
A modified vagal maneuver converted a fast heart rhythm far more often than the standard one. In a randomized trial of 433 adults in emergency departments with supraventricular tachycardia (excluding atrial fibrillation and flutter), a modified Valsalva maneuver (the strain followed by lying back with the legs raised) returned the heart to a normal rhythm in 43% (93 of 214) versus 17% (37 of 214) with the standard maneuver (adjusted odds ratio 3.7, 95% CI 2.3–5.8), with no serious adverse events. (Appelboam et al., Lancet, 201561485-4)) [3]
Trained volunteers with defibrillators saved more lives after cardiac arrest. In a trial across 993 community units, there were 30 survivors to hospital discharge among 128 arrests where volunteers were trained in CPR plus automated external defibrillator (AED) use, versus 15 among 107 where volunteers were trained in CPR alone (relative risk 2.0, 95% CI 1.07–3.77), and trained laypersons used AEDs safely. (Hallstrom et al., N Engl J Med, 2004) [4]
Implantable defibrillators lowered the risk of sudden cardiac death in people with cardiomyopathy. A meta-analysis of 13 randomized trials (7,857 patients with ischemic or non-ischemic cardiomyopathy) linked ICD therapy to lower all-cause mortality (odds ratio 0.69, 95% CI 0.55–0.87) and lower sudden cardiac death (odds ratio 0.32, 95% CI 0.24–0.43). (Jaiswal et al., Curr Probl Cardiol, 2024) [5]
At a Glance
Item | Summary |
What it is | An irregular heartbeat — too fast, too slow, or with an inconsistent pattern |
Normal resting rate | 60 to 100 beats per minute |
Fast rate (tachycardia) | Over 100 beats per minute |
Slow rate (bradycardia) | Under 60 beats per minute |
Most serious type | Ventricular fibrillation — the most frequent cause of sudden cardiac death |
Key risk factors | Heart disease, high blood pressure, thyroid disease, sleep apnea, stimulants, alcohol |
Serious complications | Stroke (from blood clots), heart failure, sudden cardiac death |
Main treatments | Medicines, vagal maneuvers, cardioversion, catheter ablation, pacemaker, ICD, maze or bypass surgery |
What Is a Heart Arrhythmia?
A heart arrhythmia (also called a cardiac arrhythmia) is an irregular heartbeat. It happens when the electrical signals that tell the heart to beat don't work as they should. The heart may beat too fast, too slow, or with an inconsistent pattern. It can feel like a fluttering, pounding, or racing heartbeat in the chest.
It is worth knowing that not all arrhythmias are dangerous. Some are harmless, while others cause life-threatening symptoms. There are also times when a fast or slow heartbeat is completely normal — your heart beats faster during exercise and slows down during sleep.
How the Heart's Electrical System Works
To understand arrhythmias, it helps to know how a normal heartbeat works. The heart has four chambers: two upper chambers called the atria and two lower chambers called the ventricles.
The heart's electrical system controls every beat. Signals start in a small group of cells at the top of the heart called the sinus node and pass through a pathway between the upper and lower chambers called the atrioventricular (AV) node. This movement of signals makes the heart squeeze and pump blood. In a healthy heart, this process runs smoothly and produces a resting heart rate of 60 to 100 beats per minute. An arrhythmia begins when something disrupts that signal pathway.
Types of Heart Arrhythmia
Heart arrhythmias are grouped by the speed of the heart rate.
Fast Heartbeat (Tachycardia)
Tachycardia means a heart rate above 100 beats a minute. The fast types differ in where they start and how dangerous they are.
Type | What happens | Notes |
Atrial fibrillation (AFib) | Chaotic heart signaling causes an irregular, often very fast heartbeat | May start and stop on its own; sometimes won't stop unless treated; linked to stroke |
Atrial flutter | Similar to AFib, but the heartbeats are more organized | Also linked to stroke |
Supraventricular tachycardia (SVT) | Irregular heartbeat starting above the ventricles | Causes a pounding heartbeat that starts and stops suddenly |
Ventricular tachycardia | Rapid heartbeat starting from faulty signals in the ventricles | The rapid beat stops the ventricles from filling, so the heart may not pump enough blood; may be an emergency in people with heart disease |
Ventricular fibrillation | Chaotic signals make the ventricles tremble instead of squeezing | Causes death within minutes if not reset; the most frequent cause of sudden cardiac death |
Slow Heartbeat (Bradycardia)
Bradycardia means a heart rate below 60 beats a minute. A low resting rate does not always signal trouble — people who are physically fit can pump enough blood with fewer beats. But if the slow heart rate means the heart isn't pumping enough blood, it may be one of these types:
Sick sinus syndrome — the sinus node sets the heart's pace; if it fails, the heartbeat switches between too slow and too fast. It is often caused by scarring near the sinus node and is most common in older adults.
Conduction block — a block in the heart's electrical pathways slows or stops the signals. Some blocks cause no symptoms; others cause skipped or slowed beats.
Premature Heartbeats (Extra Beats)
Premature heartbeats are extra beats that arrive one at a time, sometimes alternating with a regular heartbeat. Those from the top chamber are premature atrial contractions (PACs); those from the bottom chamber are premature ventricular contractions (PVCs).
An extra beat can feel like your heart skipped a beat. These are generally not a concern and rarely point to a serious condition. However, a premature beat can trigger a longer-lasting irregular heartbeat — especially in people with heart disease — and very frequent PVCs can sometimes lead to a weak heart. Stress, heavy exercise, and stimulants such as caffeine and nicotine can trigger them.
Symptoms of a Heart Arrhythmia
An arrhythmia may cause no symptoms at all and may be discovered during a routine checkup for an unrelated reason. When symptoms do occur, they can include:
A fluttering, pounding, or racing feeling in the chest
A fast heartbeat
A slow heartbeat
Chest pain
Shortness of breath
Other symptoms may include anxiety, feeling very tired, lightheadedness or dizziness, sweating, and fainting or almost fainting.
When to See a Doctor
Make an appointment for a health checkup if your heart feels like it is beating too fast, too slow, or skipping beats. You may be referred to a cardiologist — a doctor trained in heart diseases.
Emergency: Call 911 or your local emergency number immediately if you have chest pain, shortness of breath, or fainting. Always call 911 if you think you might be having a heart attack.
Ventricular fibrillation deserves special attention. It can cause a dramatic drop in blood pressure, making a person collapse to the ground within seconds. Breathing and pulse then stop. If someone collapses:
Call 911 or your local emergency number.
If no one nearby is trained in CPR, do hands-only CPR — push hard and fast on the center of the chest at 100 to 120 pushes per minute until help arrives. No mouth-to-mouth breathing is needed.
If an AED (automated external defibrillator) is nearby, have someone get it and follow its instructions. No training is needed — the device tells you what to do and is programmed to deliver a shock only when appropriate.
CPR keeps blood flowing to the organs while you wait for defibrillation, which resets the heart.
Causes of Heart Arrhythmia
The causes of heart arrhythmias are the things that change how electrical signals travel through the heart. They include:
Cause category | Examples |
Heart damage | Heart attack, or scarring from a previous heart attack |
Blood flow problems | Coronary artery disease (blocked arteries in the heart) |
Heart structure changes | Cardiomyopathy and other structural changes |
Metabolic and hormone issues | Diabetes; overactive or underactive thyroid |
Breathing problems | Sleep apnea |
Infection | COVID-19 infection |
Substances and habits | Some medicines (including cold and allergy drugs); too much alcohol or caffeine; illicit drug use or drug misuse; smoking |
Other | Genetics; stress or anxiety |
Risk Factors
Nine factors raise the risk of developing a heart arrhythmia:
Coronary artery disease, other heart conditions, and previous heart surgery — narrowed arteries, a heart attack, heart valve disease, prior surgery, heart failure, cardiomyopathy, and other heart damage are risk factors for almost any kind of arrhythmia.
High blood pressure — raises coronary artery disease risk and may make the walls of the left lower chamber stiff and thick, changing how electrical signals travel.
Congenital heart defects — heart conditions present at birth that may affect rate and rhythm.
Thyroid disease — an overactive or underactive thyroid raises the risk of irregular heartbeats.
Obstructive sleep apnea — pauses in breathing during sleep can cause slow and irregular heartbeats, including atrial fibrillation.
Changes in electrolytes — potassium, sodium, calcium, and magnesium help trigger and send electrical signals; levels that are too high or too low interfere with heart signaling.
Some medicines and supplements — certain prescription medicines and cough and cold treatments can cause arrhythmias.
Excessive alcohol use — affects the heart's electrical signaling and increases the chance of atrial fibrillation.
Caffeine, nicotine, and illicit drugs — stimulants make the heart beat faster and may lead to more serious arrhythmias. Drugs such as amphetamines and cocaine may cause sudden death from ventricular fibrillation.
Complications
Complications depend on the type of arrhythmia. The three main ones are:
Complication | What it means |
Blood clots | Clots can travel to the brain and cause a stroke. Blood-thinning medicines can lower stroke risk related to atrial fibrillation and other arrhythmias — ask your healthcare professional whether you need a blood thinner. |
Heart failure | If an arrhythmia causes heart failure symptoms, treatment to control the heart rate may help the heart work better. |
Sudden cardiac death | Most often from ventricular fibrillation, when the heart's rhythm is not reset within minutes. |
How Heart Arrhythmias Are Diagnosed
Diagnosis starts with a physical exam, a medical history review, and a discussion of your symptoms. Tests then check the heart and look for conditions that can cause an irregular heartbeat.
The Eight Main Tests
Test | What it does |
Electrocardiogram (ECG or EKG) | A quick test that measures the heart's electrical activity and shows how fast or slow it beats. Sticky sensor patches go on the chest, and sometimes the arms or legs, connected by wires to a computer. |
Holter monitor | A portable ECG worn for a day or more, recording the heart during daily activities. |
Event recorder | A portable ECG worn for up to 30 days — you press a button when symptoms occur. |
Echocardiogram | Sound waves take pictures of the beating heart, showing structure, valves, pumping strength, and blood flow. |
Implantable loop recorder | Placed under the skin in the chest when symptoms are rare; records electrical activity continuously. |
Stress test | Some arrhythmias are triggered or worsened by exercise. The heart is monitored on a stationary bicycle or treadmill; if you can't exercise, a medicine mimics the effect of exercise on the heart. |
Tilt table test | Used for fainting spells. Heart rate and blood pressure are checked lying flat, then while a table tilts you to a standing position. |
Electrophysiological (EP) study | Thin, flexible tubes are guided through a blood vessel (usually in the groin) to the heart; sensors on the tips map how electrical signals spread during each heartbeat, confirming tachycardia and finding where faulty signaling occurs. |
If an irregular heartbeat isn't found on the initial tests, one or more of the trigger tests (stress, tilt table, or EP study) may be used to provoke the arrhythmia so it can be captured on recording.
Treatment of Heart Arrhythmias
Treatment depends on whether the heart is beating too fast or too slow — and on whether the irregular rhythm causes significant symptoms or puts you at risk of a more serious condition. Some arrhythmias need no treatment at all, and your care team may suggest regular checkups to watch the condition instead.
Medicines
For most people with tachycardia, medicine is used to control the heart rate and rhythm. If you have atrial fibrillation, you may also receive blood thinners to prevent blood clots and lower stroke risk.
Therapies: Vagal Maneuvers and Cardioversion
Vagal maneuvers are simple, specific actions that slow the heart rate by affecting the vagus nerve, which helps control the heartbeat. They include coughing, bearing down as if having a bowel movement, and putting an ice pack on the face. They may be recommended for a very fast heartbeat from supraventricular tachycardia — but they don't work for all arrhythmia types.
Cardioversion uses paddles or patches on the chest to deliver an electrical shock that resets the heart rhythm. It is typically used when vagal maneuvers and medicines don't work, often for atrial fibrillation.
Procedures and Surgery
Procedure | What happens | When it's used |
Catheter ablation | Thin tubes (catheters) are guided through blood vessels to the heart; sensors at the tips use heat or cold to create tiny scars that block faulty electrical signals and restore the heartbeat. | Fast heartbeats; restoring a normal rhythm |
Pacemaker | A small device placed in the chest sends electrical signals to correct a slow beat when the cause can't be fixed. Dual-chamber devices pace the right upper and lower chambers; biventricular devices pace both lower chambers. | Slow heartbeats with no fixable cause |
Implantable cardioverter-defibrillator (ICD) | A device placed under the skin near the collarbone continuously checks the rhythm and sends low- or high-energy shocks to reset it. | High risk of dangerously fast beats in the ventricles (ventricular tachycardia or fibrillation), a history of sudden cardiac arrest, or conditions that raise that risk |
Maze procedure | A surgeon makes tiny cuts in the upper half of the heart, creating a maze of scar tissue that blocks stray electrical signals causing fast heartbeats. | Usually only when other treatments fail or you're already having open-heart surgery for another reason |
Coronary bypass graft surgery | Creates a new path for blood to flow around a blocked or partly blocked artery. | Severe coronary artery disease with an irregular heartbeat |
Sometimes open-heart surgery is needed to stop or prevent an irregular heartbeat. After treatment, keep regular checkups, take medicines exactly as directed, and tell your healthcare team if symptoms get worse.
Lifestyle Changes and Home Remedies
A heart-healthy lifestyle supports treatment and helps protect the heart:
Eat heart-healthy foods — fruits and vegetables, whole grains, fat-free or low-fat dairy, and lean proteins. Limit saturated and trans fats.
Get regular exercise — at least 30 minutes on most days.
Don't smoke — if you can't quit on your own, ask a healthcare professional about strategies or programs that can help.
Keep a healthy weight — being overweight increases heart disease risk; set realistic goals with your care team.
Manage blood pressure and cholesterol — with lifestyle changes and medicines taken as directed.
Limit or avoid alcohol — if you drink, do so in moderation: up to one drink a day for women of all ages and men older than 65, and up to two drinks a day for men 65 and younger.
Practice good sleep habits — adults should aim for 7 to 9 hours a night, going to bed and waking at the same time every day, including weekends.
Manage stress — more exercise, mindfulness practice, and connecting with others in support groups all help.
Prevention
Lifestyle changes that manage heart disease may also prevent some arrhythmias. Avoid smoking, eat a diet low in salt and saturated fat, exercise at least 30 minutes most days, maintain a healthy weight, reduce and manage stress, manage high blood pressure, cholesterol, and diabetes, get good sleep (7–9 hours for adults), and limit or avoid caffeine and alcohol.
Coping and Support
Living with an arrhythmia — especially one like AFib that may need ongoing medication or monitoring — can feel unsettling. Talk to your care team about what your specific type means for your daily life, activity level, and long-term outlook. Many people live full, active lives once their rhythm is controlled. If you feel anxious about episodes, say so: your healthcare team can help you distinguish between harmless palpitations and signs that need attention, and knowing that difference is often the most calming support of all.
Preparing for Your Appointment
Medical appointments can be brief, and there is often a lot to discuss. Here is how to make the most of yours.
What You Can Do
Ask about pre-appointment restrictions — for example, fasting before a cholesterol test.
Write down your symptoms, including any that may seem unrelated.
Write down key personal information — family history of heart disease, stroke, high blood pressure, or diabetes, plus any major stresses or life changes.
List all medicines, vitamins, and supplements with their dosages.
Take someone with you if possible — a companion can help you remember what was said.
Prepare your questions, ordered from most to least important.
Questions to Ask Your Healthcare Team
What's the most likely cause of my symptoms?
Are there other possible causes?
What kinds of tests will I need, and do I need to prepare for them?
What's the most appropriate treatment?
Are there any foods or drinks I should avoid — or add?
What's an appropriate level of physical activity?
How often should I be screened for heart disease or complications of an arrhythmia?
I have other health conditions — how can I best manage them together?
Is there a generic option for the medicine you're prescribing?
Are there brochures or other printed material I can take home, or websites you recommend?
Questions Your Doctor Will Likely Ask
When did you first begin having symptoms?
Do you always have symptoms, or do they come and go?
How severe are your symptoms?
Does anything seem to improve your symptoms?
What, if anything, makes your symptoms worse?
Does anyone in your family have a heart arrhythmia?
Frequently Asked Questions
What is a heart arrhythmia?
A heart arrhythmia is an irregular heartbeat caused by faulty electrical signals in the heart — the heart beats too fast (over 100 beats per minute), too slow (under 60), or with an inconsistent pattern. Some arrhythmias are harmless, while others can be life-threatening.
What does a heart arrhythmia feel like?
A heart arrhythmia often feels like a fluttering, pounding, or racing heartbeat in the chest. It may also cause chest pain, shortness of breath, dizziness, anxiety, tiredness, sweating, or fainting — though some arrhythmias cause no symptoms at all.
Is every fast or slow heartbeat an arrhythmia?
No. Your heart normally beats faster during exercise and slower during sleep. A resting heart rate of 60 to 100 beats per minute is considered healthy, and fit people can have rates below 60 without any problem. An arrhythmia is diagnosed when the rhythm is irregular or inappropriate for the situation.
Which types of heart arrhythmia are most dangerous?
Ventricular fibrillation is the most dangerous — the heart's lower chambers tremble instead of pumping, and it causes death within minutes if the rhythm is not reset, making it the most frequent cause of sudden cardiac death. Ventricular tachycardia can also be an emergency in people with heart disease.
What causes a heart arrhythmia?
Common causes include a heart attack or its scarring, coronary artery disease, heart structure changes such as cardiomyopathy, diabetes, high blood pressure, thyroid problems, sleep apnea, COVID-19 infection, certain medicines (including cold and allergy drugs), excess alcohol or caffeine, drug use, smoking, stress, and genetics.
How is a heart arrhythmia diagnosed?
Diagnosis uses electrical tests of the heart: an ECG or EKG measures the heart's electrical activity; a Holter monitor or event recorder captures rhythms over days to weeks; an echocardiogram images the beating heart; an implantable loop recorder continuously records rare episodes; and stress tests, tilt table tests, or an EP study can trigger and map the irregular rhythm.
How is a heart arrhythmia treated?
Treatment depends on the type and severity. Some arrhythmias need no treatment beyond regular checkups. Options include medicines to control rate and rhythm, blood thinners to prevent stroke in AFib, vagal maneuvers, cardioversion (an electrical reset), catheter ablation, pacemakers for slow hearts, implantable defibrillators (ICDs) for dangerous fast rhythms, and surgical options such as the maze procedure or coronary bypass.
Conclusion
A heart arrhythmia means the heart's electrical signals aren't doing their job — but that single idea covers everything from a harmless skipped beat to a life-threatening emergency. This guide has shown how the sinus and AV nodes keep the rhythm, what the fast, slow, and extra-beat types look like, the warning symptoms that demand a 911 call, and the full range of modern treatments that can restore a normal rhythm. The most important takeaway: if you feel your heart racing, fluttering, or skipping, get checked — and if chest pain, shortness of breath, or fainting arrive, don't wait. Early diagnosis turns a frightening experience into a manageable condition.
For a deeper dive into the most common type, read our complete guide to atrial fibrillation.
This article is for general information only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
Related Reading
Digoxin: Uses, Normal Levels and Toxicity explains digoxin and its levels.
Cardioversion: Procedure, Types, Risks and Recovery explains how cardioversion resets an abnormal heart rhythm.
Valsalva Maneuver: How to Do It and When It's Used explains a breathing technique that can stop a fast heartbeat.
Exercise Stress Test: Why It's Done, How to Prepare, What Happens and Results explains the treadmill test used to check how the heart handles exertion.
Learn more in our guide to Holter Monitor: What It Detects, How It Works and Results.
Electrocardiogram (EKG or ECG): Why It's Done, How to Prepare, What Happens and Results explains how an electrocardiogram (EKG) records your heart's electrical activity to help find rhythm problems.
Heart Rate Monitors: How They Work, Types, Accuracy and When to See a Doctor explains how heart rate monitors work, how accurate they are and when a reading needs a call to your doctor.
Learn more in our guide to Transesophageal Echocardiogram (TEE): Why It's Done, What to Expect and Risks.
Heart Screening: Which Tests Check Your Heart Health and What Results Mean explains the tests used to check your heart health and what results mean.
Troponin Test: What It Is, Why It's Done, Normal Range and What High Levels Mean explains the heart blood test that can rise with this condition and how results are read.
Implantable Loop Recorder (ILR): What It Is, How It's Placed and What It Shows explains the long-term heart monitor that can catch rhythm problems linked to this condition.
Electrophysiology (EP) Study: Why It's Done, What Happens and Recovery explains the catheter test that maps the heart's electrical system to diagnose arrhythmias.
Cardiac Event Monitor: Types, How to Wear It and How It Differs From a Holter explains the weeks-long heart rhythm monitor for symptoms that come and go.
References
Mayo Clinic Staff. Heart arrhythmia - Symptoms and causes. Mayo Clinic. April 23, 2026. https://www.mayoclinic.org/diseases-conditions/heart-arrhythmia/symptoms-causes/syc-20350668
Mayo Clinic Staff. Heart arrhythmia - Diagnosis and treatment. Mayo Clinic. April 23, 2026. https://www.mayoclinic.org/diseases-conditions/heart-arrhythmia/diagnosis-treatment/drc-20350674
Appelboam A, et al. Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT): a randomised controlled trial. Lancet. 2015;386(10005):1747-53. PMID 26314489. https://doi.org/10.1016/S0140-6736(15)61485-4
Hallstrom AP, et al. Public-access defibrillation and survival after out-of-hospital cardiac arrest. N Engl J Med. 2004;351(7):637-46. PMID 15306665. https://doi.org/10.1056/NEJMoa040566
Jaiswal V, et al. Implantable cardioverter defibrillators for primary prevention in patients with ischemic and non-ischemic cardiomyopathy: A meta-analysis. Curr Probl Cardiol. 2024;49(2):102198. PMID 37952790. https://doi.org/10.1016/j.cpcardiol.2023.102198
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