An arrhythmia is any heartbeat that doesn’t follow the normal rhythm, whether it’s too fast, too slow, or irregular. A normal resting heart rate falls between 60 and 100 beats per minute, though most healthy adults sit between 55 and 85. When the electrical signals controlling your heartbeat misfire or travel along the wrong path, the result is an arrhythmia. Some are harmless and barely noticeable. Others are serious enough to cause fainting, stroke, or cardiac arrest.
How Your Heart’s Electrical System Works
Your heart has its own built-in pacemaker, a small cluster of specialized cells in the upper right chamber called the sinus node. This node fires an electrical impulse 60 to 100 times per minute under normal conditions. Each impulse travels from the sinus node down to a relay station between the upper and lower chambers, where it pauses briefly. That pause is important: it gives the upper chambers time to squeeze blood into the lower chambers before those larger, more powerful lower chambers contract and push blood out to the lungs and body.
An arrhythmia happens when something disrupts this sequence. The sinus node might fire too slowly or too quickly. The electrical signal might take a wrong turn, loop back on itself, or get blocked by scar tissue. Extra electrical impulses can pop up from tissue that isn’t supposed to generate signals at all. The location of the disruption and the type of malfunction determine which kind of arrhythmia you have.
Types of Arrhythmia
Arrhythmias fall into a few broad categories based on speed and location.
Bradycardia
A resting heart rate below 60 beats per minute. This isn’t always a problem. Well-trained athletes can have resting rates in the 40s and feel perfectly fine. But if a slow heart rate comes with weakness, lightheadedness, or shortness of breath, it usually means the heart’s electrical system isn’t generating or conducting signals properly.
Tachycardia
A resting heart rate above 100 beats per minute. This category includes several distinct conditions depending on where the abnormal signals originate. A resting rate consistently above 90 is worth mentioning to your doctor, even if it doesn’t technically cross the 100 threshold.
Supraventricular Arrhythmias
These start in the upper chambers of the heart. The most common is atrial fibrillation (AFib), which causes chaotic electrical activity that can push the upper chambers to fire more than 400 times per minute. The upper and lower chambers fall out of sync, reducing the heart’s pumping efficiency and allowing blood to pool, which raises the risk of clots and stroke. Globally, more than 59.7 million people have AFib, and that number is climbing. In the United States alone, projections estimate 12.1 million people will have AFib by 2030.
Atrial flutter is a related condition where the upper chambers beat 250 to 350 times per minute in a more organized but still abnormal pattern, often caused by scar tissue blocking signals. Paroxysmal supraventricular tachycardia (PSVT) is a type that starts and stops suddenly, sometimes lasting seconds, sometimes hours.
Premature Heartbeats
These are extra beats that feel like your heart skipped or added a beat. They’re extremely common and usually harmless on their own. Most people experience them at some point without ever knowing it.
What It Feels Like
Many arrhythmias produce no symptoms at all and are only discovered during a routine exam. When symptoms do appear, people describe them in a few characteristic ways: a racing sensation, pounding in the chest, a flip-flopping feeling, fluttering, or the sense that beats are being skipped or added. Some people notice these sensations for a few seconds, while others feel them for minutes or longer.
More concerning symptoms include dizziness, lightheadedness, feeling faint, chest tightness, or unusual fatigue during normal activities. A sudden collapse or loss of consciousness, a racing heart paired with dizziness, or chest pain are signs that require emergency care immediately.
Causes and Triggers
Arrhythmias can stem from structural problems in the heart, like damage from a heart attack, valve disease, or heart failure. High blood pressure over time can thicken the heart walls and change how electrical signals travel. Thyroid disorders, particularly an overactive thyroid, directly affect heart rate. Imbalances in electrolytes like potassium, magnesium, and calcium alter the electrical properties of heart cells and can trigger abnormal rhythms even in an otherwise healthy heart.
Some arrhythmias are congenital, meaning you’re born with extra electrical pathways or other structural differences. Others develop gradually with age as the heart’s conduction tissue wears down or develops scar tissue.
When it comes to everyday triggers, alcohol is the most consistently validated one for AFib. A UCSF clinical trial that tracked participants using mobile heart monitors found that alcohol consumption was the only trigger that reliably increased the likelihood of an AFib episode. Caffeine, despite its reputation, showed no evidence of triggering atrial fibrillation in the same study. In fact, other research from the same institution suggested caffeine may actually have a slight protective effect. Other commonly suspected triggers like poor sleep, large meals, and cold drinks were logged by participants but not validated by the data.
How Arrhythmias Are Diagnosed
A standard electrocardiogram (EKG) is usually the first test. It records your heart’s electrical activity, but only for the few seconds you’re hooked up to the machine. That’s a limitation, because many arrhythmias come and go. If your symptoms are intermittent, a normal EKG doesn’t rule anything out.
A Holter monitor solves this problem by recording your heart rhythm continuously for 24 to 48 hours while you go about your day. It can catch arrhythmias that a brief EKG misses, identify the cause of unexplained palpitations or dizziness, and check whether medications are working. For arrhythmias that happen even less frequently, longer-term monitors can be worn for weeks, or a small device can be implanted under the skin to record for months or years.
Treatment Options
Treatment depends entirely on the type of arrhythmia, how severe it is, and whether it’s causing symptoms or raising your risk of complications like stroke. Many arrhythmias need no treatment at all.
Medications
For fast heart rates, the most common medications work by slowing the heart rate or steadying the rhythm. Rate-controlling drugs reduce how fast the lower chambers beat, which helps even if the upper chambers are still firing irregularly. Rhythm-controlling drugs target the abnormal electrical signals themselves, slowing down the heart’s ability to conduct electricity in ways that help restore a normal pattern. Blood thinners are frequently prescribed alongside these for AFib patients to reduce stroke risk.
Cardioversion
This is a procedure that resets the heart’s rhythm using a controlled electrical shock delivered through pads on the chest. It’s done under sedation and takes only a few seconds. It’s most commonly used for AFib or atrial flutter when the heart needs a “reboot” back to its normal rhythm. It works well in the short term, though the arrhythmia can return.
Catheter Ablation
Ablation is a more targeted approach. A thin, flexible tube is threaded through a blood vessel (usually in the groin) to the heart, where it delivers energy to destroy the small areas of tissue causing the abnormal electrical signals. For persistent AFib, five-year success rates reach about 56% after multiple procedures, with roughly 46% of those patients staying off rhythm-controlling medications entirely. For certain types of arrhythmia originating from a single spot, success rates run higher, in the range of 70% to 80% over five years. Recovery typically involves a day or two of rest with soreness at the catheter insertion site.
Implanted Devices
Pacemakers treat slow heart rhythms by sending small electrical impulses to keep the heart beating at an appropriate rate. Implantable defibrillators monitor for dangerously fast rhythms and deliver a shock to restore normal rhythm if one occurs. Both are placed under the skin near the collarbone in a procedure that typically takes one to two hours.
Living With an Arrhythmia
For most people, an arrhythmia is a manageable condition rather than a life-altering diagnosis. Reducing or eliminating alcohol is one of the few lifestyle changes with strong evidence behind it for preventing AFib episodes. Staying on top of conditions that feed into arrhythmias, like high blood pressure, thyroid problems, and sleep apnea, makes a meaningful difference in how often episodes occur and how severe they are.
Tracking your symptoms matters. Noting when episodes happen, how long they last, and what you were doing or consuming beforehand gives your doctor useful information that a single office visit can’t capture. Wearable heart-rate monitors and smartwatches have made this easier, though they aren’t a substitute for medical-grade monitoring when a diagnosis is needed.