COVID-19 is mainly a lung infection, but it can also unsettle the heart’s rhythm, and atrial fibrillation is the rhythm problem it triggers most often.1PubMed Central. COVID-19-Associated Cardiovascular Complications: A Narrative Literature Review The risk tracks how sick the infection makes you. It is a real concern in the hospital and a small one after an ordinary case at home. The link also outlasts the infection, because a slightly higher chance of AFib lingers for months after recovery.2PubMed. Risk of incident atrial fibrillation after COVID-19 infection: A systematic review and meta-analysis
How Often COVID-19 Leads to AFib
In atrial fibrillation (AFib), the heart’s upper chambers quiver chaotically instead of squeezing in rhythm, which makes the pulse irregular and often fast. It can come and go in episodes or stay constant. Some people feel nothing at all, while others notice fluttering, breathlessness or tiredness.
Among nearly 28,000 US patients hospitalized with COVID who had never had AFib, about 5.4% developed it during that stay.3PubMed. New-Onset Atrial Fibrillation in Patients Hospitalized With COVID-19: Results From the American Heart Association COVID-19 Cardiovascular Registry A separate large hospital group found about 4% developing it for the first time.4PubMed Central. Atrial Fibrillation in Patients Hospitalized With COVID-19
The numbers climb with severity. In intensive care, studies found AFib appearing for the first time in 10.7% to 14.6% of COVID patients.5PubMed Central. New-Onset Atrial Fibrillation in the Critically Ill COVID-19 Patients Hospitalized in the Intensive Care Unit In one hospital, all new rhythm problems occurred in ICU patients, about 27.5% of them, and none on ordinary wards.6PubMed Central. New-Onset Atrial Fibrillation in the Critically Ill COVID-19 Patients Hospitalized in the Intensive Care Unit Among patients on a breathing machine with severe lung failure, about 24% developed it.7PubMed Central. New-Onset Atrial Fibrillation in the Critically Ill COVID-19 Patients Hospitalized in the Intensive Care Unit
These percentages overstate the risk for people who recovered at home. Hospitalized patients were older and sicker, often with heart or kidney disease already, and many were on oxygen or ventilators, which strain the heart. A cold-like case at home places far less stress on the heart’s rhythm. Your own age and heart health matter as much as the infection does.
Most people who had COVID were never hospitalized, so these numbers do not describe them. Across all recovered patients, though, the risk of AFib stays somewhat raised for over a year, as the recovery section explains.
In the hospital, continuous heart monitors catch even silent AFib. At home, short silent episodes can go unnoticed, which is why symptoms or a watch alert matter. A doctor confirms AFib with an ECG, a quick, painless test of the heart’s electrical signals.
To check at home, rest for five minutes, then feel your pulse at the wrist for a full minute. A steady beat, even a fast one, is less typical of AFib than a pulse that speeds up and slows with no pattern. A pulse check suggests but does not prove AFib, so a new irregular or racing pulse that does not settle should be recorded with an ECG.
Why the Virus Disrupts Heart Rhythm
COVID can push the immune system into overdrive, flooding the body with inflammatory signals.8PubMed Central. COVID-19 and atrial fibrillation: Intercepting lines These signals can injure heart muscle cells and disturb how electrical impulses travel through the upper chambers.9PubMed Central. COVID-19 and atrial fibrillation: Intercepting lines
Like other infections, COVID activates the body’s fight-or-flight system.10PubMed Central. Atrial Fibrillation in COVID-19: Mechanisms, Clinical Impact, and Monitoring Strategies The resulting surge of stress signals overloads heart cells with calcium, which can set off extra stray beats that start AFib.11PubMed Central. Atrial Fibrillation in COVID-19: Mechanisms, Clinical Impact, and Monitoring Strategies Low oxygen levels and disturbed blood salts like potassium add to the electrical instability.12PubMed Central. COVID-19-Associated Cardiovascular Complications: A Narrative Literature Review Fever and dehydration also raise heart rate and stress the rhythm.
The virus can damage the lining of small blood vessels and cause tiny clots, starving patches of heart muscle of blood.13PubMed Central. COVID-19-Associated Cardiovascular Complications: A Narrative Literature Review In the heart, the doorway the virus uses to enter cells sits mostly on cells wrapped around the smallest vessels.14PubMed Central. Role of angiotensin-converting enzyme 2 and pericytes in cardiac complications of COVID-19 infection
Severe lung illness adds another layer. When the lungs struggle, the heart must pump harder against raised pressure in the lung vessels, and the right side of the heart can become stretched. A stretched upper chamber is more prone to electrical misfires, so lung trouble can lead to rhythm trouble even without direct damage to the heart. That is part of why those with the most severe lung failure show the highest rates. A very sick patient often has several of these routes at once, which helps explain why ICU patients have far higher rates than ward patients.
Does AFib Linger After Recovery
Over about 14 months after infection, around 2.6% of recovered people developed new AFib.15PubMed. Risk of incident atrial fibrillation after COVID-19 infection: A systematic review and meta-analysis That was about 1.57 times the risk of people who never had COVID over the same time.16PubMed. Risk of incident atrial fibrillation after COVID-19 infection: A systematic review and meta-analysis People with long COVID had about a 49% higher AFib risk than comparison groups.17PubMed Central. Increased Arrhythmia Risk in Long COVID: A Systematic Review and Meta-Analysis Most recovered people never get AFib, but some do who otherwise would not have.
Inflammation and low oxygen effects on the heart’s electrical system are thought to persist in some people after the illness.18PubMed Central. Cardiac Effects in Post–COVID-19 Heart Failure: A Systematic Review of Longitudinal Imaging- and Biomarker-Based Structural and Functional Remodeling An earlier infection, even one that caused no symptoms, has also been suggested as a factor in AFib after heart surgery, through lingering vessel and inflammation effects.19The Atlantic Journal of Medical Science and Research. Postoperative atrial fibrillation after isolated coronary artery bypass grafting: The role of previous clinically silent SARS-CoV-2 infection
In everyday numbers: if the comparison group had about 1.7 cases per 100 over the same period, the recovered group had about 2.6 per 100, under one extra case per 100 people. About 97 of every 100 recovered people did not develop AFib in this period. That difference matters for health systems because millions had COVID, but for one person it is a modest addition. Age, blood pressure, weight and alcohol still drive most AFib risk.
Not every palpitation after COVID is AFib. Many people have a fast but regular heartbeat afterward, especially on standing, and a regular racing pulse differs from the irregular, unpredictable beat of AFib. Only an ECG or monitor can tell them apart, so mention any palpitations to a doctor.
Why AFib During COVID Is Taken Seriously
In one group of COVID patients, those who developed AFib for the first time had blood clots far more often, about 42% versus 4%.20Cardiology Journal. New-onset atrial fibrillation during COVID-19 infection predicts poor prognosis They also bled more often, about 33% versus 5%, and stayed in hospital about twice as long.21Cardiology Journal. New-onset atrial fibrillation during COVID-19 infection predicts poor prognosis AFib lets blood pool in the heart and form clots, while the clot-preventing drugs used to counter that raise bleeding risk.
These figures come from hospitalized, often critically ill patients. They do not mean nearly half of people with AFib after COVID will have a clot, and sicker patients are more likely both to develop AFib and to have clots.
In AFib the upper chambers do not empty fully, so blood moves slowly and can pool, especially in a small pouch of the left upper chamber where clots tend to form. A clot formed there can travel to the brain and cause a stroke. COVID itself also makes blood more likely to clot, which doubles the concern. That is why doctors often consider blood thinners when AFib appears. These drugs, also called anticoagulants, reduce the blood’s ability to clot and so lower the chance a clot forms and travels. They do not dissolve clots already there, and they raise bleeding risk, so the decision is made individually.
People who already had AFib before catching COVID faced about twice the risk of dying.22PubMed Central. Pre-existing atrial fibrillation is associated with increased mortality in COVID-19 Patients They needed breathing support more often and were more likely to be readmitted.23PubMed Central. Does new onset and pre-existing atrial fibrillation predict mortality in COVID-19 patients?
Chest pain, fainting or severe breathlessness with a racing, irregular pulse need emergency care. Sudden face drooping, arm weakness or slurred speech may mean stroke, so call emergency services. Milder new fluttering still warrants a prompt doctor visit.
If You Already Have AFib and Catch COVID
The COVID pill Paxlovid must not be taken with the rhythm drugs dronedarone, propafenone or quinidine.24Pfizer Inc.. Fact Sheet for Healthcare Providers: Emergency Use Authorization for PAXLOVID With amiodarone or flecainide it should only be used if heart and pharmacy specialists plan it together.25PubMed Central. Cardiovascular Drug Interactions with Nirmatrelvir/Ritonavir for COVID-19: Considerations for Daily Practice Digoxin can be combined only with blood level checks.26PubMed Central. Cardiovascular Drug Interactions with Nirmatrelvir/Ritonavir for COVID-19: Considerations for Daily Practice The reason is that Paxlovid raises blood levels of these drugs, which can itself cause dangerous rhythms.27Pfizer Inc.. Fact Sheet for Healthcare Providers: Emergency Use Authorization for PAXLOVID Tell the prescriber every heart medicine you take before starting it.
Paxlovid contains ritonavir, which slows the liver enzymes that normally break down many medicines, so those drugs build up in the blood. For rhythm drugs, a build-up can mean too much of the medicine, which can disturb the heartbeat. The effect can last a few days after the last Paxlovid dose, so the prescriber also needs to plan for that period.
Some blood thinners used in AFib can also be affected, so the pharmacist or doctor may adjust the dose or choose a different approach for the course. Cholesterol drugs such as simvastatin can build up too and may be paused for the days of treatment.
Preparation helps before you ever get sick. Keep an up-to-date list of medicines and doses on your phone, and ask your heart doctor now which COVID treatment suits you. Do not stop a heart medicine on your own to make room for Paxlovid. If you are hospitalized, ask whether your blood thinner needs adjusting.
While ill at home, check your pulse, or your watch reading if you own one. Stay hydrated, since fever and fluid loss can provoke episodes. Report a pulse that is faster or more irregular than usual to your doctor.
Vaccination and Spotting AFib Early
Over two years after infection, vaccinated people developed new AFib slightly less often, 1.91% versus 2.18%.28PubMed Central. The impact of COVID-19 vaccination on long-term risk of new-onset atrial fibrillation/flutter after COVID-19 infection: A retrospective cohort study The lower risk held even when only mild and moderate cases were counted,292 Minute Medicine. COVID-19 vaccination is associated with reduced risk of new-onset atrial fibrillation following COVID-19 infection and the benefit showed from the first month onward.30PubMed Central. The impact of COVID-19 vaccination on long-term risk of new-onset atrial fibrillation/flutter after COVID-19 infection: A retrospective cohort study
The gap is about a quarter of a percentage point, small for one person but meaningful across millions. Vaccinated people may differ from unvaccinated people in ways that affect heart health, so the study cannot prove vaccination alone caused the difference.
Smartwatches and fitness trackers caught about 94% of AFib and rarely flagged it in people without it.31JMIR mHealth and uHealth. Wearable activity trackers could offer early clues on COVID-19 Still, about 1 in 8 alerts may be wrong, so an alert needs an ECG to confirm.
When your watch alerts, note the time and how you feel, and save the ECG strip if it records one. Share it with your doctor rather than ignoring it or panicking. Seek urgent care if the alert comes with chest pain, fainting or stroke signs.
Other habits protect your rhythm after COVID. Control blood pressure and limit alcohol, both common AFib triggers. Return to exercise gradually after illness, and get untreated sleep apnea checked, since it also drives AFib.