Can viruses or bacteria cause atrial fibrillation (AFib)?

Can Viruses or Bacteria Cause Atrial Fibrillation?

Yes, infections from viruses and bacteria can trigger atrial fibrillation through inflammatory mechanisms, with infection-related AF carrying significant long-term risks similar to other forms of AF. 1, 2

Infection as a Cause of Atrial Fibrillation

• Acute infections, including viral and bacterial infections, are recognized as temporary causes of atrial fibrillation, alongside other conditions like excessive alcohol intake, surgery, pericarditis, myocarditis, hyperthyroidism, and pulmonary embolism 3
• Infection-related AF is associated with worse outcomes, including a 25-fold increased risk of recurrent AF and twice the risk of thromboembolic events compared to patients with infection without AF 2
• COVID-19 infection has been shown to cause a significantly higher incidence of new-onset AF (7.0%) compared to other lower respiratory tract infections (3.6%) 4

Pathophysiological Mechanisms

• Infections can trigger AF through inflammatory processes that create an arrhythmogenic substrate in the atria 3, 5
• Inflammation leads to structural changes in the atria including fibrosis, hypertrophy, and altered wall stress that promote AF 3, 5
• Toll-like receptor 2 (TLR2) levels on monocytes are significantly up-regulated in patients with non-valvular AF, suggesting an infectious inflammatory component in AF pathogenesis 6
• Specific bacterial infections, including Helicobacter pylori and Chlamydia pneumoniae, have been hypothesized to be involved in the pathogenesis of AF through chronic inflammatory processes 7
• Myocarditis (inflammation of the heart muscle) caused by viral, bacterial, or other infectious agents can lead to inflammatory cardiomyopathy and increase the risk of arrhythmias including AF 3

Clinical Implications

• Patients who develop AF during an infection have a 36.4% risk of recurrent AF within one year, challenging the previous notion that infection-related AF is a transient phenomenon 2
• Risk factors for developing new AF during infections include older age, pre-existing heart conditions (especially heart failure, ischemic heart disease, or peripheral vascular disease), and higher CHA₂DS₂-VASc scores 4
• Despite the high risk of thromboembolic events, patients with infection-related AF (particularly COVID-19) are less likely to receive appropriate anticoagulation at discharge compared to other forms of AF 2, 4

Management Considerations

• The European Heart Journal recommends evaluating for potentially reversible causes of AF, including infections 5
• Beta-blockers appear safe for both prevention and rate control of infection-associated AF, even in patients requiring vasopressors 1
• Given the high recurrence rate and thromboembolic risk, infection-related AF may merit similar treatment and follow-up as AF not related to infection 2
• Patients with infection-related AF should be considered for long-term anticoagulation based on their CHA₂DS₂-VASc score, similar to other forms of AF 1, 2

Special Populations

• Older patients with pre-existing cardiovascular disease are at highest risk of developing AF during infections 4
• Patients with sepsis and severe infections have a particularly high risk of developing new-onset AF, which is associated with worse outcomes 1