**Please see independent tick researcher John Scott’s comment regarding climate change and tick expansion after the article.**
Lyme Carditis: Heart Block and Other Complications of Lyme Disease
by Adrian Baranchuk, MD, FACC ,FRCPC, FCCS, and Cynthia Yeung, BSc
The incidence of Lyme disease, a tick-borne bacterial infection, is rapidly increasing in North America. Risk modeling suggests that the incidence of Lyme disease will continue to rise as the migratory birds that are responsible for transmitting the Ixodes tick are affected by climate change and consequently, contribute to the expansion of at-risk regions. Lyme disease can affect many organ systems, including the heart, nerves, and joints.
In this article, the authors intend to highlight one of the most dramatic complications of Lyme disease, early dissemination Lyme carditis.
How Common Are Lyme Disease And Lyme Carditis?
Lyme disease is the most commonly reported vector-borne disease in North America, with an annual incidence of approximately 25, 000 confirmed cases in the United States. However, estimates suggest that the true incidence is closer to 300, 000 cases annually. Lyme disease affects the heart in 0.3-10% of cases.
Lyme Carditis: How Spirochetes Affect The Heart
In Lyme carditis, Borrelia burgdorferi (the spirochete responsible for Lyme disease) directly affects the heart. Damage to the heart tissue occurs from the direct invasion by the bacteria, as well as from the body’s exaggerated immune response to the infection.
In 90% of cases, the most common consequence of Lyme carditis is heart block. Electrical signals from the upper chambers of the heart are not properly relayed to the lower chambers of the heart, which can dramatically slow down the heart rate.
The severity of the heart block can fluctuate rapidly and the progression to complete heart block can be fatal. Importantly, the heart block in Lyme carditis can be transient and usually resolves with antibiotic therapy. Additionally, Lyme carditis can affect other parts of the heart’s conduction system, as well as the heart’s muscle, valves, and outer layer of the heart wall.
Symptoms Of Lyme Carditis
Patients with Lyme carditis may report light-headedness, fainting, shortness of breath, palpitations, and/or chest pain. Conversely, patients with Lyme carditis may also experience no symptoms, which contributes to the elusive nature of the diagnosis.
Systematic Approach For Lyme Carditis
To help healthcare providers consider Lyme carditis as a potential cause for heart block, our research team developed the Suspicious Index in Lyme Carditis (SILC) score.
It allots points for specific risk factors. The resulting score classifies patients into low, intermediate, and high-risk categories for the likelihood that the heart block is due to Lyme carditis. The variables in the SILC score can be associated with the mnemonic “CO-STAR”: Constitutional symptoms, Outdoor activity/endemic area, Sex (male), Tick bite, Age (< 50 years), and Rash.
Table 1. The Suspicious Index in Lyme Carditis (SILC) score evaluates the likelihood that a patient’s high-degree heart block is caused by Lyme carditis. The total score indicates low (0-2), intermediate (3-6), or high (7-12) suspicion of Lyme carditis.
Age < 50 years 1
Outdoor activity/endemic area 1
Constitutional symptoms* 2
Tick bite 3
Erythema migrans rash 4
* fever, malaise, arthralgia, and dyspnea
Patients with high-degree heart block and a SILC score of three or higher should be investigated immediately for Lyme disease. They should also receive antibiotic treatment while awaiting the results of testing.
Importance Of Prompt Recognition And Treatment Of Lyme Carditis
The standard protocol for high-degree heart block calls for implanting a permanent pacemaker. However, the heart block in Lyme carditis will most likely resolve with antibiotic therapy. Thus, identifying Lyme carditis as the underlying cause of the heart block can prevent the unnecessary implantation of permanent pacemakers.
The battery of a pacemaker lasts 7-10 years. Thus, a missed diagnosis could subject an otherwise young, healthy patient to 5-7 battery replacements over a lifetime—with each procedure bringing potential adverse events. These risks associated with the initial pacemaker implantation can be mitigated by intravenous and oral antibiotic treatment for heart block caused by Lyme carditis.
Educating Healthcare Providers
We aim to raise awareness about the cardiac manifestations of Lyme disease in endemic areas, so that healthcare providers are educated and alert about Lyme carditis. The conduction disorders associated with Lyme carditis can progress quickly. Patients often seek medical attention several times before Lyme carditis is suspected. The prompt diagnosis and treatment of Lyme carditis is essential to prevent unnecessary implantation of permanent pacemakers and further complications of Lyme disease.
- Wan D, Baranchuk A. Lyme carditis and atrioventricular block. CMAJ 2018;190:E622.
- Fuster LS, Gul EE, Baranchuk A. Electrocardiographic progression of acute Lyme disease. Am J Emerg Med 2017;35:1040 e5-1040 e6.
- Wan D, Blakely C, Branscombe P, Suarez-Fuster L, Glover B, Baranchuk A. Lyme Carditis and High-Degree Atrioventricular Block. Am J Cardiol 2018;121:1102-1104.
Dr. Baranchuk, a cardiologist and professor of medicine at Queen’s University, Kingston, Canada, is one of the world’s leading experts on Lyme carditis. Cynthia Yeung is a medical student.
Birds, not climate change, brought ticks
Re: “Balance key to addressing climate change: expert,” Jan. 19.
I do not agree with Roberta Bondar’s statement: “The migration of deer ticks [blacklegged ticks] into the Kingston area, and the increased incidents of Lyme disease is an example of the kind of environmental changes that climate change is bringing.”
My peer-reviewed scientific research shows that migratory songbirds import blacklegged tick larvae and nymphs into Canada, and are widely dispersing them countrywide. In fact, a heavily tick-infested songbird can initiate a new blacklegged tick population. The number of immature blacklegged ticks on migratory song birds has remained constant for decades — long before climate change was coined. Furthermore, the adult female blacklegged tick does not migrate at all, and crawls a maximum of six metres in her lifetime.
I believe federally funded researchers who publish peer-reviewed papers on tick expansion numbers, ascribed to being caused by climate change, are wasting millions of taxpayer dollars. Moreover, their research is not helping patients get diagnosed and treated in a timely manner. Alarmingly, we have 3,000 patients going to the United States for diagnosis and treatment of Lyme disease and associated tick-borne diseases.
Any daily temperature increases are not putting any extinction stressors on the blacklegged female. She lays her eggs in the cool, moist leaf litter, where she has typically laid them for millennia, and is very comfortable in this microhabitat. She does not have extinction stress in this environment and, thus, does not lay more eggs. The seemingly more ticks in the Kingston area, and everywhere else, is not because of climate changing. In reality, public awareness is the key factor because more people, veterinarians and pet groomers are looking for them.
John D. Scott
Please know there’s a ton of money when it is ear-marked with the words “climate change,” but regarding tick expansion and therefore the spread of Lyme, it isn’t being honest and it’s taking valuable resources and money away from things that really matter. Scott goes as far to say it’s a nefarious plot protecting authorities from the lack of helpful research and care for patients that’s occurred over the span of 40 years.
http://www.dutchessny.gov/CountyGov/Departments/Legislature/2017Auerbach.pdf This pdf by Lyme Advocate Jill Auerbach shows that while there were only 5,700 cases of WNV in 2012, research dollars were $29 million, whereas, Lyme cases in 2012 were 312,000 but received only $25 million. Another stark contrast is Hepatitis C in 2012 with 1,300 cases but with $112 million in research dollars.
While the number of the infected continue to soar, the research dollars for Lyme are radically reduced in successive years. Go here for a quick table comparing research dollars for various diseases: https://madisonarealymesupportgroup.com/2018/09/17/study-shows-tick-infection-transmission-potential-for-both-dtv-wnv/
THIS DOES NOT EVEN INCLUDE OTHER TICK-BORNE DISEASES
Don’t kid yourself. Words mean things and any research ear marked with the words “climate change” have not and will not help patients one iota.