An arrhythmia most commonly feels like a fluttering, pounding, or racing sensation in your chest. Some people describe it as a skipped beat, a sudden thud, or a heart that seems to pause and then restart with extra force. The sensation varies depending on the type of rhythm problem, and roughly one-third of people with certain arrhythmias feel nothing at all.
The Most Common Sensations
People use a wide range of words to describe what an irregular heartbeat feels like, but a few descriptions come up again and again: fluttering, pounding, racing, and skipping. You might feel your heart doing something unusual for just a second or two, or the sensation might last minutes to hours. Some people notice it only when they’re quiet and still, while others feel it during activity.
The “skipped beat” feeling is one of the most reported. What’s actually happening is a premature beat, where the heart fires slightly earlier than expected. The beat itself is often too weak to feel, so what you notice is the brief pause afterward and the stronger-than-normal beat that follows. That combination creates the sensation of a skip and then a thud or flip in your chest.
How Different Types Feel
Premature Beats (PVCs and PACs)
These are the most common arrhythmias, and they’re usually harmless. The extra beats originate from either the upper or lower chambers of the heart, firing sooner than they should. You might feel a single flutter, a skipped beat, or a pounding sensation that lasts only a moment. Most people experience these occasionally without realizing it. They become noticeable when they happen in clusters or when you’re paying close attention to your heartbeat, like when lying in bed at night.
Atrial Fibrillation (AFib)
AFib produces a distinctly chaotic sensation because the upper chambers of the heart quiver rapidly and irregularly instead of contracting in a coordinated rhythm. People often describe it as butterflies in the chest or, more vividly, a fish flopping around behind the ribcage. The heartbeat feels completely unpredictable rather than just fast or slow. Episodes tend to start suddenly, sometimes lasting minutes and sometimes days. Beyond the chest sensation, AFib commonly causes lightheadedness, shortness of breath, and a general feeling of being drained.
About one-third of AFib cases are discovered without the person ever noticing symptoms. These “silent” cases are typically caught during routine checkups or when a doctor investigates something unrelated. So if you’ve been told you have AFib but never felt anything unusual, that’s not uncommon.
Fast Heart Rate (Tachycardia)
When the heart beats too quickly, typically well above 100 beats per minute at rest, the dominant sensation is a rapid pounding or racing in the chest. It can feel like your heart is trying to beat its way out. Some episodes start and stop abruptly, as if someone flipped a switch. You may also feel anxious, sweaty, or short of breath, and some people experience chest pressure or feel faint.
Slow Heart Rate (Bradycardia)
A slow arrhythmia, where the heart drops below 60 beats per minute, feels very different from a fast one. You’re less likely to feel your heart doing something strange and more likely to notice what your body can’t do. The hallmark symptoms are dizziness, unusual fatigue (especially during physical activity), confusion, and fainting or nearly fainting. These happen because the heart isn’t pumping blood fast enough to keep the brain and muscles well supplied with oxygen. Some people also develop shortness of breath or chest pain.
In a condition called bradycardia-tachycardia syndrome, the heart alternates between too slow and too fast. This can produce a confusing mix of symptoms: sluggishness and lightheadedness one moment, racing and pounding the next.
Symptoms Beyond Your Chest
Not every arrhythmia announces itself with a dramatic heartbeat sensation. Many people first notice secondary effects: sudden exhaustion during a walk they normally handle fine, dizziness when standing, breathlessness that seems out of proportion to what they’re doing, or a vague feeling that something is “off.” These symptoms happen because an irregular rhythm reduces the heart’s efficiency at pumping blood, so your organs get less oxygen than they need.
Chest discomfort can also accompany arrhythmias, though it’s usually a pressure or tightness rather than sharp pain. Fainting is one of the more serious secondary symptoms and tends to occur with very fast or very slow rhythms that dramatically reduce blood flow to the brain.
Why It Feels Worse Lying Down
If you notice palpitations more when you’re in bed, you’re not imagining it. Lying down, particularly on your left side, compresses the chest cavity and brings the heart closer to the chest wall, making each beat more noticeable. The position also changes pressure on the heart and blood flow patterns, which can trigger or amplify the sensation. Simply rolling onto your back or right side often reduces the feeling. A quiet room with no distractions also means there’s nothing competing for your attention, so you’re more tuned in to what your heart is doing.
Arrhythmia vs. Anxiety Palpitations
This is one of the trickiest distinctions because the two can feel nearly identical. Both cause a racing or pounding heart, chest tightness, and shortness of breath. A few subtle differences can help you tell them apart, though they’re not foolproof.
Anxiety-driven palpitations tend to build gradually alongside emotional distress, fear, or a stressful situation. You’ll usually notice other anxiety symptoms too: sweating palms, a sense of dread, rapid breathing, tingling in the fingers. The heart speeds up but generally maintains a regular rhythm.
Arrhythmia episodes are more likely to start abruptly with no emotional trigger. You might be sitting calmly, reading, or even waking from sleep when the sensation hits. The rhythm often feels irregular or chaotic rather than just fast. AFib episodes in particular tend to begin suddenly rather than building up. That said, the differences are subtle, and anxiety can also trigger real arrhythmias in people who are prone to them. If you’re repeatedly experiencing palpitations that come on without an obvious emotional cause, a heart monitor worn over several days can capture what’s actually happening electrically during an episode.
Signs That Need Immediate Attention
Most arrhythmias are brief, benign, and more annoying than dangerous. But certain combinations of symptoms signal that the heart rhythm problem is significantly affecting blood flow. Fainting or losing consciousness during palpitations is the clearest red flag. Severe chest pain, significant difficulty breathing, sudden confusion, or feeling like you might pass out all warrant urgent evaluation. A heart rate that stays above 150 beats per minute at rest or drops low enough to make you dizzy and weak also falls into this category.
For palpitations that are brief and infrequent, with no dizziness, fainting, or chest pain, a scheduled appointment is reasonable. Keeping a log of when episodes happen, how long they last, and what you were doing at the time gives your doctor useful information for deciding whether monitoring is needed.