The authorized COVID-19 vaccines have undergone the necessary clinical trials to deem them safe and effective. However, as with any type of medication, there is a potential risk of side effects. Most health organizations do not list arrhythmias as a side effect, but some sources suggest it may be a rare adverse event.

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COVID-19 vaccines refer to a group of vaccinations that can help provide protection from SARS-CoV-2 infection. Since the development of these vaccines, researchers continue to monitor possible side effects, which can include tiredness, headaches, and muscle pain.

Some sources suggest that arrhythmia, or an irregular heartbeat, is a possible adverse reaction. While this could be possible, most research indicates that the risk of arrhythmia is generally low and supports data on the safety of the vaccine.

In this article, we will discuss the potential relationship between COVID-19 vaccines and arrhythmias, as well as how the vaccine may affect the heart.

A person receiving their COVID vaccine.Share on Pinterest
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An arrhythmia involves an irregular heartbeat. The Centers for Disease Control and Prevention (CDC) does not list cardiac arrhythmias as a possible side effect of the COVID-19 vaccine. But as with any vaccine, some people may experience uncommon side effects. Additionally, it is not always clear if an adverse condition is directly due to the vaccine.

Still, some research indicates that the COVID-19 vaccine may cause arrhythmia as a side effect. For example, a 2022 analysis reviewed information from the FDA Adverse Event Reporting System (FAERS) to search for incidents of atrial fibrillation, which is a type of arrhythmia. Researchers reviewed the reports of atrial fibrillation after the use of the Pfizer, Moderna, AstraZeneca, Johnson & Johnson vaccines, along with the influenza vaccine.

The researchers found the percentage of all adverse events reported attributed to atrial fibrillation were as follows:

  • Pfizer: 2.6%
  • Moderna: 1.8%
  • AstraZeneca: 0.6%
  • Influenza: 0.4%
  • Johnson & Johnson: 0%

The data indicates that there could be a possible association between the vaccines and atrial fibrillation, although the potential risk is still relatively low. Further research is necessary to understand the correlation and why atrial fibrillation may occur in a small percentage of people after vaccination.

Some evidence notes that arrhythmias are a potentially life threatening complication of COVID-19. As such, this would suggest that the benefits of receiving the vaccine and having immunity to SARS-CoV-2 outweigh the potential risks.

However, it is worth noting that the incidence and prevalence of atrial fibrillation is increasing globally. Some evidence suggests that in the United States alone, roughly 3–6 million people have atrial fibrillation, and that number could reach 6–16 million by 2050.

Although considered uncommon, in a small percentage of people, the COVID-19 vaccine may adversely affect the heart. A 2022 cohort study found that although the vaccines are safe, there are reports of myocarditis and pericarditis.

Myocarditis involves inflammation of the heart muscle, and pericarditis is inflammation of the outer lining of the heart. Symptoms of both conditions may include:

  • arrhythmias
  • chest pain
  • shortness of breath
  • fatigue

According to the CDC, cases of myocarditis reported to VAERS have occurred more often in adolescent and young adult males. Reports also indicate that myocarditis developed more often after the second dose and usually within 1 week after vaccination.

According to research in a 2022 retrospective study, vaccine-associated myocarditis shows an injury pattern on an MRI similar to other causes of myocarditis. But the abnormalities are less severe with vaccine-associated myocarditis. A 2021 study notes that most cases of vaccine-related myocarditis in people younger than 21 were mild and resolved fast.

Additionally, a 2022 systematic review and meta-analysis states that the overall risk of myopericarditis after a COVID-19 vaccine is low and the risk of heart inflammation is similar to that following vaccination against other diseases.

Adverse effects on the heart occurring due to the COVID-19 vaccine appear to be uncommon. However, the COVID-19 infection itself has the potential to affect the heart in multiple ways. A 2022 review indicates there is a link between arrhythmias, cardiomyopathy, heart attacks, and SARS-CoV-2 infection.

According to the National Heart, Lung, and Blood Institute, COVID-19 may cause excessive inflammation in the heart muscle that can disrupt electrical signals. This can result in arrhythmia and possibly cause blood clots to form. The virus may also infect the cardiac cells, which can contribute to heart damage. One 2021 study found that traces of SARS-CoV-2 were detected in the heart tissue of 60% of those that died from the infection.

Notably, a 2021 study investigating the prevalence of myocarditis in competitive athletes after SARS-CoV-2 infection found that 2.3% had myocarditis. This is much higher than the potential risk of heart inflammation after the COVID-19 vaccine.

According to the CDC, possible side effects of COVID-19 vaccines may include:

  • pain at the injection site
  • swelling and redness at the injection site
  • fatigue
  • headache
  • joint pain
  • fever
  • chills
  • nausea

An arrhythmia occurs when something goes wrong with the electrical signals in the heart. There are many more common causes of arrhythmias than the COVID-19 vaccine.

Several factors can contribute to or cause arrhythmia. According to the National Heart, Lung, and Blood Institute, various types of heart and blood vessel diseases, such as heart attack, heart inflammation, and congenital heart disease, can cause arrhythmia.

Other possible causes include:

  • too little or too much thyroid hormones
  • illegal drug use, such as amphetamines
  • dehydration
  • viral infections
  • caffeine
  • high or low blood sugar levels
  • extreme stress or emotions, such as anger
  • low levels of electrolytes, such as calcium and potassium

Individuals that experience an abnormal heartbeat after receiving the COVID-19 vaccine or with a SARS-CoV-2 infection should contact a doctor. While an arrhythmia may not indicate anything serious, in some cases it can signal a cardiac problem. It is best to see a medical professional to determine the significance of the arrhythmia.

Typically, COVID-19 vaccine side effects are minor and only last a few days. But the CDC recommends contacting a doctor if side effects do not go away in a few days.

In rare instances, signs of a serious adverse reaction require immediate medical evaluation. According to the American Heart Association, people that get the vaccine should seek professional medical care as soon as possible if they develop:

  • shortness of breath
  • leg swelling or pain
  • chest pain
  • severe headache
  • nausea and vomiting
  • persistent back or abdominal pain

An arrhythmia describes an irregular heartbeat. Some evidence suggests that arrhythmia, and other heart problems, are a potential side effect of the COVID-19 vaccine. However, while it is a possible adverse reaction, the risk is low and healthcare specialists state that the vaccine is safe.

COVID-19 itself can increase the risk of potential heart complications. As such, it is advisable to receive the vaccine as the benefits outweigh any potential risks. As with any vaccine, some people may find it helpful to consult with a healthcare professional to discuss any concerns.