A heart arrhythmia is any heartbeat that doesn’t follow the normal rhythm. Your heart might beat too fast, too slow, or in an irregular pattern. Some arrhythmias are harmless and last only seconds, while others are chronic conditions that raise your risk of stroke or heart failure. Atrial fibrillation alone affects over 52 million people worldwide, and roughly 4.5 million new cases are diagnosed each year.
How Your Heart’s Electrical System Works
Your heart runs on electricity. A small cluster of specialized cells in the upper right chamber, called the sinus node, generates an electrical impulse that tells your heart when to beat. That signal travels down to a relay station between the upper and lower chambers (the AV node), where it pauses briefly to let the upper chambers finish contracting. From there, the impulse splits into two pathways that run down through the lower chambers, triggering them to pump blood to your lungs and body.
An arrhythmia happens when something disrupts this pathway. The sinus node might fire too quickly or too slowly. The signal might take a wrong turn and loop back on itself. Or a rogue cluster of cells somewhere else in the heart might start firing its own electrical impulses, competing with the normal rhythm. The result depends on where the disruption occurs and how it alters the timing of your heartbeat.
Common Types of Arrhythmia
Arrhythmias fall into a few broad categories based on speed and location.
Atrial Fibrillation
Atrial fibrillation (AFib) is the most common arrhythmia. The upper chambers fire chaotically, sometimes exceeding 400 electrical impulses per minute. Because the upper and lower chambers fall out of sync, the lower chambers can’t fill with blood properly and pump less efficiently. AFib can come and go in episodes or become permanent. Its biggest danger is blood pooling in the upper chambers and forming clots. As little as six minutes of atrial fibrillation significantly raises stroke risk.
Supraventricular Tachycardia
Supraventricular tachycardia (SVT) causes sudden episodes of rapid heartbeat originating in the upper chambers. It starts and stops abruptly, often during intense physical activity. SVT is relatively common in younger people and is usually not dangerous, though the racing sensation can be alarming.
Bradycardia
Bradycardia means your heart beats too slowly, generally below 60 beats per minute. For well-trained athletes, a slow resting heart rate is normal. But when bradycardia stems from a faulty sinus node or a blocked electrical signal, the heart may not pump enough blood to meet your body’s needs. This can cause fatigue, dizziness, or fainting.
Ventricular Arrhythmias
Arrhythmias originating in the lower chambers (ventricles) tend to be more serious because the ventricles are responsible for pumping blood out of the heart. Ventricular tachycardia produces a dangerously fast heart rate that can deteriorate into ventricular fibrillation, a chaotic quivering that effectively stops blood flow. Ventricular fibrillation is a cardiac emergency and the leading cause of sudden cardiac death.
What Arrhythmias Feel Like
Many arrhythmias produce no symptoms at all, especially in early stages. When symptoms do appear, the most common is palpitations: a fluttering, pounding, or racing feeling in your chest. You might also feel lightheaded, short of breath, or unusually tired. Some people notice their heart seems to skip a beat or add an extra one.
Certain symptoms signal a more serious situation. A sudden collapse or loss of consciousness requires emergency care immediately. Palpitations combined with dizziness and lightheadedness, or any chest pain accompanying an irregular rhythm, also warrant an emergency visit. For younger people, a family history of sudden death at a young age or inherited heart conditions is a significant red flag that makes any new rhythm symptoms worth investigating promptly.
What Causes Arrhythmias
The triggers range from temporary and reversible to chronic and structural. High caffeine or alcohol intake, dehydration, stress, and sleep deprivation can all provoke short-lived rhythm disturbances in an otherwise healthy heart. Certain medications, including some cold remedies and supplements, can also trigger episodes.
More persistent arrhythmias often have an underlying cause. Coronary artery disease, high blood pressure, and heart valve problems can all damage or remodel heart tissue in ways that disrupt electrical signals. Thyroid disorders (both overactive and underactive) alter the hormonal signals that influence heart rate. Diabetes, obesity, and sleep apnea each independently increase arrhythmia risk. Some people are born with extra electrical pathways or structural differences that predispose them to rhythm problems from a young age.
How Arrhythmias Are Diagnosed
A standard electrocardiogram (EKG) is usually the first test. It records your heart’s electrical activity for about 10 seconds, which is enough to catch an arrhythmia that’s happening at that moment but easy to miss if your episodes are infrequent.
For arrhythmias that come and go, longer monitoring fills the gap. A Holter monitor records your heart rhythm continuously for 24 hours or more, giving your doctor a “movie” of your electrical activity instead of a snapshot. If your episodes are even less frequent, a cardiac event recorder can be worn for a month or two, capturing data only when you activate it or when it detects an abnormality.
Other tests help identify both the arrhythmia and its cause. An exercise stress test monitors your rhythm while you walk or run on a treadmill, since physical exertion can provoke arrhythmias that don’t appear at rest. An echocardiogram uses ultrasound to show your heart’s size, structure, and pumping function. For people who faint, a tilt-table test tracks how heart rate and blood pressure respond to position changes. And for complex cases, an electrophysiology (EP) study threads thin catheters into the heart itself to map the exact electrical pathways and deliberately trigger arrhythmias under controlled conditions so they can be precisely diagnosed.
Treatment Options
Treatment depends entirely on the type and severity of the arrhythmia. Many people with occasional, mild rhythm disturbances need no treatment at all beyond managing triggers like caffeine, alcohol, or stress.
Medications
Several classes of drugs can help control arrhythmias. Some work by slowing the electrical signals that pass through the heart, reducing the chance of abnormal impulses taking hold. Others target the heart’s response to adrenaline, lowering the heart rate and calming overactive electrical circuits. A third group extends the resting period between heartbeats, making it harder for rogue signals to trigger extra beats. For AFib specifically, blood thinners are often prescribed alongside rhythm-controlling drugs to reduce the risk of stroke from blood clots forming in the upper chambers.
Catheter Ablation
Ablation is a procedure where a thin, flexible tube is guided through a blood vessel to the heart. Once positioned at the site of the abnormal electrical pathway, the catheter delivers energy (usually heat or extreme cold) to create a small scar that blocks the faulty signal. For SVT, the success rate ranges from 90% to 95%. For AFib, atrial tachycardia, and ventricular tachycardia, success rates are lower, between 60% and 80%.
Recovery from the procedure itself takes only a few hours, and most people return to desk work within five to seven days. You’ll need to avoid heavy lifting and intense exercise for at least a week. One thing that catches people off guard: arrhythmias can continue for up to three months after ablation while the heart tissue fully heals. This doesn’t necessarily mean the procedure failed.
Implanted Devices
A pacemaker treats bradycardia by delivering small electrical pulses to keep the heart beating at an adequate rate. For dangerous ventricular arrhythmias, an implantable cardioverter-defibrillator (ICD) continuously monitors the rhythm and delivers a shock to reset the heart if it detects a life-threatening pattern. Both devices are implanted under the skin near the collarbone in a procedure that typically takes one to two hours.
The Link Between Arrhythmia and Stroke
Atrial fibrillation is the arrhythmia most strongly associated with stroke. When the upper chambers quiver instead of contracting effectively, blood can pool and form clots. If a clot travels to the brain, it causes a stroke. Continuous cardiac monitoring after a first stroke detects AFib in more than 20% of survivors over three years, compared to just 2.5% detected through standard follow-up care. That tenfold difference highlights how often AFib goes unnoticed, silently raising stroke risk in people who don’t realize they have it.
Beyond stroke, chronic arrhythmias can weaken the heart muscle over time. When the heart beats too fast, too slow, or too irregularly for months or years, it gradually loses pumping efficiency. This can lead to heart failure, where the heart can no longer meet the body’s demands for blood and oxygen.