Symptoms of Cardiac Arrhythmias

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Cardiac arrhythmias can produce a range of symptoms, from very mild (or even none) to life-threatening. These symptoms can be divided into a “classic” group of symptoms that should make a doctor look specifically for a cardiac arrhythmia as the likely cause and an “other” group of symptoms that are just as likely to be caused by other medical conditions. Despite some symptoms being more suggestive of an arrhythmia, any symptom listed here could be caused by a variety of conditions.

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Classic Symptoms

Many people who are diagnosed with a cardiac arrhythmia will express surprise that they have experienced no symptoms.

However, it is the case that many times cardiac arrhythmias may not produce any symptoms at all.

This is especially true for arrhythmias that produce intermittent “extra” heart beats—premature atrial complexes (PACs) and premature ventricular complexes (PVCs).

Others may experience these classic symptoms.


Palpitations are an unusual awareness of the heartbeat. They are commonly experienced as disturbing skips or pauses, intermittent heartbeats that feel too strong or pounding, episodes of rapid or “runaway” heartbeats, or heartbeats that are perceived to be irregular instead of steady.

Palpitations affect different people in different ways. Some people don’t find them particularly annoying, while others find them extremely distressing and frightening.

Almost any cardiac arrhythmia can produce palpitations, including the many types of bradycardia (slow heart rates) and tachycardia (rapid heart rates), PACs and PVCs, or episodes of heart block.


If a cardiac arrhythmia is preventing the heart from pumping blood sufficiently to provide the body’s needs, episodes of lightheadedness may result. When an arrhythmia is producing lightheadedness, it is more likely to do so when you are upright, or when you are doing something active. Resting or lying down tends to improve this symptom.

Lightheadedness is a common symptom that has many potential causes in addition to arrhythmias.

But when an arrhythmia produces lightheadedness, it is a sign that the arrhythmia itself may be dangerous, and may lead to even more severe problems such as syncope or even cardiac arrest.

Because lightheadedness may be a sign of a potentially dangerous problem, this is a symptom that should never be ignored, but should always be evaluated by a physician.


Syncope, or transient loss of consciousness, is a fairly common problem that (like lightheadedness) has numerous potential causes, many of which are pretty benign.

But when syncope is caused by a cardiac arrhythmia, that’s a good sign that the arrhythmia itself is quite dangerous.

It usually means that the arrhythmia is preventing the brain from receiving enough oxygen to maintain consciousness.

Episodes of syncope can result from either bradycardia (if the heart rate is slow enough), or tachycardia (if the heart rate is fast enough).

For this reason, an episode of unexplained syncope always requires a full medical evaluation, to pinpoint the underlying cause. Any arrhythmia that has caused syncope should be considered potentially life-threatening and should be treated aggressively.

Cardiac Arrest

cardiac arrest occurs when the heart stops beating. Although there may be other causes for this, the main consideration is the function of the electrical activity of the heart and the heart's rhythm.

While severe bradycardia may cause a cardiac arrest, most often this condition is produced by ventricular fibrillation or ventricular tachycardia. Cardiac arrest invariably leads to rapid death (and is the main cause of sudden death), unless either the arrhythmia terminates by itself, or effective cardiopulmonary resuscitation is administered within a very few minutes.

Anyone who has survived a cardiac arrest should be considered to be at high risk for subsequent episodes of cardiac arrest and should receive aggressive and effective therapy.

Most of these people will be strong candidates for an implantable defibrillator.

Cardiac system without and with arrhythmia.

Other Symptoms

In addition to these classic symptoms, cardiac arrhythmias may also produce several less specific, more generalized symptoms that may not necessarily point a doctor toward considering an arrhythmia as the cause.

Most of these “other” symptoms are related to an arrhythmia causing a relative reduction in the ability of the heart to pump blood to the body’s organs. These symptoms are more likely to occur when a person is upright or exerting him/herself; and in people who have other medical conditions in addition to the arrhythmia, such as heart failure, diabetes, lung problems, or coronary artery disease.

These symptoms include:

  • Fatigue
  • Dyspnea (shortness of breath)
  • Poor exercise tolerance
  • Generalized weakness
  • Confusion
  • Chest pain

When to See a Doctor

Any of these symptoms should prompt a visit to the doctor. An episode of severe lightheadedness or unexplained syncope should be evaluated immediately, and warrants a call to 911. 

Arrhythmia Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Old Man

While many cardiac arrhythmias are fairly common and usually benign, others are dangerous and need to be treated. This means it is important for your doctor to identify whether an arrhythmia is producing your symptoms, and if so, which specific arrhythmia is causing the problem, and how aggressive to be in treating it. 

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