Lyme disease increases risk of atrial fibrillation
Atrial fibrillation, the most common type of arrhythmia (irregular heartbeat), can increase your risk of strokes, heart disease or other heart-related complications. In many cases, atrial fibrillation is associated with a history of cardiac inflammation, writes Szymanska et al. in their article “History of Lyme Disease as a Predictor of Atrial Fibrillation.”
Although researchers have gained a better understanding of atrial fibrillation, also called AFib or AF, many of the causes and risk factors are still unknown. Now, for the first time, a study examines the prevalence of atrial fibrillation in Lyme disease patients.
“It is hypothesized that in some cases the AF [atrial fibrillation] might be a consequence of past low-grade myocarditis,” the authors explain. “One of the understudied, potential sources of carditis is Borrelia infection-causing Lyme disease and Lyme carditis.”
The authors looked at 113 adult patients with atrial fibrillation, who were attending a cardiac clinic in Poland between 2018 and 2019 and compared them with 109 patients with no history of AFib. The mean age of study participants was 75.8 years, with 40% male.
Atrial fibrillation patients were more likely to suffer from obesity, hypertension, chronic kidney disease, and heart failure than patients in normal sinus rhythm. AFib patients were also more likely to have left atrial enlargement.
Borrelia and the Heart
Multiple studies have shown that Borrelia bacteria can infect all parts of the heart including the conduction system, endocardium, cardiac muscle, and cardiac blood vessels, or heart valves.
“The more common location for the [Borrelia] spirochete-associated inflammation are fibers at the base of the heart, basal interventricular septum, and perivascular regions,” the authors write.Study shows that exposure to Borrelia infection is associated with an increased risk of atrial fibrillation. Click To Tweet
Unfortunately, few intravital atrial biopsies are performed so not much is known about atrial inflammation, caused by Borrelia infections, especially in patients with atrial fibrillation.
There have been several case reports of atrial fibrillation in Lyme disease patients. But, “most reported AF as an additional ﬁnding in patients with atrioventricular blocks associated with Lyme carditis,” the authors write.
This is believed to be the first study to explore the prevalence of atrial fibrillation in Lyme disease patients.
“The study showed that patients with AF [atrial fibrillation] are over 8 times more likely to have positive Borrelia antibodies,” writes Szymanska.
According to the authors, 34.5% of the patients with AFib had a positive Borrelia infection compared to only 6.4% of patients in normal sinus rhythm.
They also report that “the presence of the anti-Borrelia IgG antibodies was a strong independent predictor of [atrial fibrillation] AF (odds ratio 8.21; 95% confidence interval 3.08 to 21.88; p <0.0001).
The authors suggest two possible reasons for the higher prevalence of AFib in Lyme disease patients:
“This might indicate a history of low-grade Borrelia-associated inﬂammation of Lyme disease and could potentially result in atrial remodeling and AF.”
And secondly, “Borrelia burgdorferi may persist in the extracellular matrix for a long time and induce cross-reactive antibodies that react with self-components, resulting in autoimmune injury.”
The authors noted limitations of their study. They did not include a confirmatory Western Blot test due to costs and availability. Their results need to be verified. And an association is not enough to establish causation.
“Certainly, larger and better-designed studies are needed to conﬁrm the association between Lyme disease and AF, but for now, it is important for physicians treating patients in endemic areas to consider Lyme carditis as a potential cause for [atrial fibrillation] AF.”
- Szymanska A, Platek AE, Dluzniewski M, Szymanski FM. History of Lyme Disease as a Predictor of Atrial Fibrillation. Am J Cardiol. 2020;125(11):1651-1654.