by Wendy Adams, Research Grant Director and Advisory Board Member, Bay Area Lyme Foundation


Recently, we’ve started to hear more about Lyme carditis as one potentially lethal manifestation of Lyme disease.  What exactly is it, why does it happen, and how does it cause disease?

What is Lyme Carditis?

First of all, a little Latin.  When you see the suffix “-itis”, it denotes inflammation – often caused by an infection.  So, carditis literally means inflammation of the heart.

When a Borrelia infection enters the body, we know from animal studies that it disseminates quickly.  It tries to find the tissues where it is most comfortable, and often that includes the heart.  Borrelia can infect all parts of the heart – the myocardium, the pericardium, and the endocardium, the cardiac muscle, the valves, and even the aorta itself.  The immune system senses the presence of the spirochete bacteria and induces inflammation, the first prong of the immune system’s response.

The inflammation instigated by the infection can cause an impairment of the electrical signal conduction between the atria and the ventricles.  This rhythm disruption is called atrial-ventrical (AV) block. AV block is very serious and probably the most common type of Lyme carditis.

AV Block

Image courtesy of the Children’s Heart Specialists

When the electrical signal conduction is impaired, the rhythm and mechanical beating of the heart (think the “lub-dub” rhythm) gets out of sync.  Without correct syncing of these contractions, the blood might not be in the correct chamber to get pumped out to the rest of the body at the right time, starving the body of blood and oxygen.

There are three degrees of AV block, with third-degree being the most serious.  In a third-degree block, the heart stops pumping blood reliably to the body and sudden cardiac death may occur.  A permanent pacemaker is inserted inside the body to get the heart to pump blood reliably.  Permanent pacemakers require servicing several times over the course of a patient’s lifetime, each time involving an invasive surgery.

When AV block is caused by Lyme disease, however, it can usually be reversed by administering antibiotics – without inserting a permanent pacemaker.  A temporary pacemaker can be used to support electrical conduction function until the antibiotics begin to fight the infection and inflammation subsides.   Being able to treat the AV block with antibiotics, as opposed to a permanent pacemaker, greatly decreases costs and improves the quality of the rest of the patient’s life.


The symptoms of AV block include dizziness, shortness of breath, syncope (fainting), palpitations and chest pain, similar to a heart attack.  Hopefully, the patient gets to the ER quickly, where the ER doctor would perform a cardiac workup and see an aberrant heart rhythm.

Sadly, in case studies of Lyme carditis, sometimes these patients are sent home with diagnoses of flu, meningitis, and mononucleosis, even with a history of a tick/insect bite and rashes.

Who’s At Risk?

Only 4-10% of patients with Lyme disease develop Lyme carditis, and only 1% develop AV block.  However, as with other Lyme statistics, the reporting of Lyme carditis is usually based on a positive two-tiered test – since this test is very insensitive early on, these incidence statistics may be grossly underestimated.  Lyme carditis patients also seem to be less likely to have a rash (40% of total), although that statistic is based on a small number of cases.

Importantly,  Lyme carditis seems to strike mostly young male patients up to 40 years old and as young as 14 – a population who wouldn’t usually be suffering from heart disease.

Eight fatal cases of Lyme carditis have been documented in medical journals, some of which could have been prevented by correct initial diagnosis of Lyme disease and prompt administration of antibiotics.

It’s time for the CDC and the IDSA to communicate that Lyme is not a benign disease where delayed diagnosis has no consequences.  Delayed diagnosis of Lyme is not only problematic, it can be fatal.  




Fuster, LS et al., “Electrocardiographic progression of acute Lyme disease.”  2017 Jul;35(7):1040.e5-1040.e6. doi: 10.1016/j.ajem.2017.02.052. Epub 2017 Mar 1.

Michalski, B, et. al, “Lyme Carditis Buried Beneath ST-Segment Elevations,”  2017;2017:9157625. doi: 10.1155/2017/9157625. Epub 2017 Jun 21..

Muehlenbachs, A., et al., “Cardiac Tropism of Borrelia burgdorferi: An Autopsy Study of Sudden Cardiac Death Associated with Lyme Carditis.”  2016 May;186(5):1195-205. doi: 10.1016/j.ajpath.2015.12.027. Epub 2016 Ma.,

Wendy A.

Wendy Adams. As a member of the science committee and Advisory Board, Wendy Adams provides strategic research advice and identifies, vets, and manages our research opportunities, including the Lyme Disease Biobank. Her unique perspective and knowledge as a former Lyme patient—as well as her background in finance, strategy and business development for companies like Cowen, Genentech and Aviron—make her skill set uniquely valuable to BAL. Wendy has spent over 20 years in the biotechnology field and most recently served as Chief Business Officer at Full Spectrum Genetics, Inc., an antibody engineering company pursuing programs in immuno-oncology and autoimmune disease.

28 Comments on “Getting to the Heart of the Issue – Lyme Carditis: Why Early Diagnosis is Critical

  1. Went to the ER with 90/50 BP and Heart Rate at 40. I was told that I most likely had Lyme and A/V Heart Block. I said give me the Antibiotics and I will go home. The ER Doc spent 20 minutes telling me I may be going over a cliff soon and need to get to the bigger hospital an hour away that has a heart unit. I listened to him.

    Went by ambulance to the bigger hospital and checked into a room and was put on a heart monitor. Two hours later, the Cardiologist came back and said I was being moved to ICU with 3rd-degree heart block and long 7-8 second heart pauses. Spent 6 days in ICU with my heart rate dropping into the low 20s and four times heart flutter. When I would sleep, my heart would go into the teens and then flutter, so I stayed awake most of the time.

    On the sixth morning, I was awakened at 4 a.m. and asked if I was OK as my heart was in flutter. I said yes, and a team was being scrambled to put in a pacemaker which I did not want. I was quite down but noticed when I would laugh my heart went into sinus rhythm so I thought I wonder if it would do it too if I sang. Sure enough, when I sang praise songs my heart went into rhythm. I spent the next two hours praising God as He performed a miracle on me. My heat went from 20 beats to 70 beats and stayed there as I sang, and from that point on I was healing. The next day, I passed an 11-minute stress test perfectly and no more pauses. Was discharged and finished another 21 days of Doxycycline. So far, EKG appears normal and I am back to walking 40 minutes a day with no problem. Will test the heart in the gym this week.

    I certainly will be checking better for ticks. I did test positive twice for Lyme, had the flu-like symptoms, but no rash. It appears to have been caught early, so my hope is no permanent damage after a good scare. I am so sorry to hear the reports here of those who did not catch it early and greater damage was done to their hearts. I am very happy I did not go back home from the ER… but went to the bigger hospital that may have been a disaster. Now must pay the bills :{, but they are worth it!

  2. In 1995, I was diagnosed with Lyme after I experienced what was thought a heart attack. The medical team took two weeks to diagnose the issue as Lyme carditis. After treatment and six weeks of rest, I returned to work and life with reduced physical ability. Before this, I had no documented heart issues or conditions (37 y/o). Fast forward to 2017 (22 yrs), I thought I was experiencing a heart attack. After admission to the hospital, it was found I did not have a heart attack but did have an aneurysm in the left ventricle and right heart failure similar to ARVD (scaring & EF at 22%). I’ve been recently placed on the transplant list category 5. Question – are they any other cases known where Lyme carditis has caused long-term issues?

  3. For nearly 3 years, I’ve had progressively worsening cardiac arrhythmia. I saw a cardiologist in early 2017, and even tho my general practitioner thought it was unnecessary, she gave me the referral. They ran several tests, did an echo on my heart, and determined its normal and functional. Cardiologist said I have PACs and he’s not certain why so often but I’d be ok. Holter meter 2 days and several EKGs revealed nothing alarming. In the meantime, years have gone by and it’s gotten worse. I mentioned my suspicion that this could be Lyme, both doctors immediately dismissed.

    Working in Land Management the past 10 years, I’ve been exposed to several situations where I could have been infected. But because I live in a California mountain town, I was told my tick fears were silly. I explained that my work often takes me to lower elevations in neighboring Nevada and I’ve worked in foothill regions of California as well. Deer ticks do exist!! I never had a bullseye rash, but I did have a bizarre rash in winter of 2015 as well as a nasty flu episode. I can’t help but wonder if it was not long before all that that I might have been infected.

    My first arrhythmia episode was discovered in a routine physical to clear me for working out in a program at my agency. The doctor said my heart rate was off and ordered an EKG. From that she had concerns. That was April 2016. I’m pretty freaked out at the progression of my arrhythmia and doctors continue to assure me I’m fine and send me home. Last week I saw a different doctor and explained in addition to palpitations and funky rhythms, skipped beats, etc, I was getting dizzy at work. Naturally it was another wasted visit. Mountain doctors know nothing about Lyme!

    What can I do? Seek out a specialist to test me in the Bay Area? I’m terrified I’m well-along in progression if I do have Lyme and if it’s progressed to carditis, that’s even scarier for me.

    1. Alecia, Bay Area Lyme is not a clinical organization and unfortunately cannot offer you specific advice, however we would recommend that you speak with an informed doctor or care provider. The International Lyme and Associated Diseases Society (ILADS) hosts a directory of care providers familiar with Lyme and related tick-borne illnesses and might be a good place to start in helping you to find someone knowledgeable in your area. Do continue to monitor and document all symptoms as it will help your doctor diagnose you. Best wishes.

  4. There is a lot more than 1% affected with Lyme carditis.. I can tell you that… I’m at one of the best Lyme Clinics now in Florida and 75% of people here have heart issues and there’s over 100 people here… I’m from NC… and I’m friends with Dr. Neil Spector, an oncologist from Duke.. He almost died and had to have a heart transplant because of Lyme… 4 years of heart issues and shortness of breath and no one could find anything… look him up… he’s all over Internet and Lyme… his book is Lyme Disease: Gone in a Heartbeat!!!! I myself have been to 14 cardiologists and none have seen anything but PVC.. which they say is normal??? Even after almost fainting and struggling to breathe on treadmill after 2 minutes they said I was fine??? Point Is…. if your heart is beating…. they say your good…. that’s all they look for…. and EKG is a joke… you can’t tell what a person’s heart is doing in 5/10/15 seconds…….SMH… 30 minutes later could be totally different….

    1. Hi Harold, Let me first say how happy I am you found help. I’ve had Lyme disease twice in the past eight years. I reside in N.E. PA. I had to seek out doctors for appropriate antibiotic treatment throughout the years. About a year ago, I was told I had a heart murmur. I was also told I had cognitive and shortness of breath symptoms. Many doctors don’t recognize Lyme disease, as you know. Ironically, I have a home in Florida, would you mind sharing where you are receiving treatment? Thank you…and I hope you continue to heal. Cathy Aristide

  5. I was diagnosed with acute heart failure (EF 10%), AV block, LBBB, and myocarditis in July 2017. As I lived in a region with a high incidence of Lyme (Dutchess County, NY), I was tested during hospitalization for Lyme but it was negative. No other risk factors for heart disease, no genetic markers, and otherwise healthy and active 50-year-old woman. I was treated with IVIG therapy, implanted with a biventricular ICD, and started on standard regimen of medications for CHF. My EF improved to 50% but I still have knee pain, bouts of extreme fatigue, shortness of breath, palpitations, etc. I recently found a photo of a lesion on my scalp that I took in October 2017, about 9 months before my CHF diagnosis, which I believe was a tick bite. I strongly suspect that I have Lyme carditis / stage 3 Lyme disease. I am scheduled to see an Infectious Disease physician soon. My question is… “When AV block is caused by Lyme disease, however, it can usually be reversed by administering antibiotics – without inserting a permanent pacemaker”… Is AV block reversible in late disseminated Lyme disease? And, can a biventricular ICD be removed? I am thrilled to think there might be a cure for my heart issues but also frankly angry about what I’ve been through. I was sent by ambulance to an out-of-network hospital for a cardiac catheterization and I am over $500,000 in medical debt due to claims denied. Thank you for the research and advocacy.

  6. My labrador and myself have suffered with undiagnosed Lyme. Thank goodness a new diagnostic panel multiplex 2018 fda approved is better than antiquated cd6. The bacteria has and continues to morph — I found out about a study conducted out of Texas A&M Veterinary for ticks in South/Eastern regions. The days of super bugs is here. My fog suffers with AV node PVCs and coupling as well as microalbumururia!! Scary and confusing. What are the meds (IV) recommended?? Thanks and best of luck to everyone — this is a serious health threat and docs are not knowledgeable.

  7. On May 24, 2017, I passed out at work with no prior symptoms. I was hospitalized for 2 days and nothing was found (brain, heart, etc.). I then passed out again on May 28, 2017 and was hospitalized for 2 days again. Nothing was found. I had a halter heart monitor for 2 weeks after that and nothing irregular was found. I had a Lyme test run and tested positive on 5 of the 7 markers. I took a 2-week dose of Doxycycline. Then in July of 2017, I passed out again. This time they implanted a heart monitor. Nothing showed until on October 26, 2017, I almost passed out. This time, they say that my heart stopped for 10 seconds. On November 13, 2017, I had a pacemaker implanted. I have not had any syncope episodes since. However, I still do not have an answer as to why my heart was stopping except that it was a 3rd degree A/V Block. I have suspected Lyme Carditis, but my doctors all say it couldn’t be that. I am a 54-year old female. I just want answers…..

  8. Back in July 2018, I got really sick and went to the doctor and they could not figure out what was wrong with me. And then I remembered that me and my boyfriend went hiking so I asked the doctor to do a test for Lyme and it came back positive for rocky mountain spotted fever and Lyme disease and that was after I had been sick for 2 weeks. So they gave my the doxycycline and I was on that for almost the whole month of August and then right after I got off the doxycycline my chest started hurting along with my back in between my shoulder blades and I have all the symptoms of Lyme carditis. Here it is in October and the pain is just worsening and the pain is shooting in my arm and I get so lightheaded that I am going to faint but don’t and this feeling of like you’re on a rollercoaster and its dropping feeling going through my body. I am so weak and can’t do any exercises or anything because it brings my symptoms on and I don’t have any idea of who to go to or what to do?!

    1. Maria, We would strongly encourage you to speak with a doctor experienced with Lyme and other tick-borne illnesses like Rocky Mountain Spotted fever. You should be able to find a knowledgeable physician in your area using the ILADS physician referral service. Please do make sure to document and share all your symptoms with your doctor so they can best advise you. We sincerely hope you get the help you need. Best wishes.

  9. Please help. Though not yet confirmed by the ELISA test, I had a tick incident followed by flu, which was overlooked by doctors, and now have late Lyme symptoms — all of them, including now Carditis. I had a what seemed like a heart attack the other night and was cold along with all the symptoms mentioned above. Mom rushed me to ER. Was pale, weak, dizzy, faint, and breathing into winter coat to tend to my cold body with hard breathing issues. Body temp low, heart rate down. Constant chest pain since, back to the ER for an EKG but normal (run for 5 seconds, not two minutes!). My entire upper body is under pressure and pain. It’s hardish to breath. UVMMC has managed and overlooked this case, Vermont. I didn’t have the EM rash, but I did develop a rash on eyelids. Didn’t have severe heart issues until after starting doxcycline mono one week ago, which helped other symptoms but then this heart attack. Stopped the meds for a day, yesterday, to see if allergic to meds but still the problem persisted. Suspect Carditis, so restarted meds and am wondering if I should take 3 pills a day, so 300 mg total? I can’t get the intravenous drugs unless positive. Please respond if you have insight. I will be doing a WBT. Should I use Igenics lab? What a mess this all is. Why can’t we see this damn thing under the microscope? It is all ridiculous.

  10. I just got out of the hospital after experiencing Stage 3 heart block. I was driving to work, when suddenly I started feeling light headed. I travel for work so I called my wife to tell her something was wrong. I thought I was having an anxiety attack. I started losing consciousness so my wife called 911. When I got me to the hospital they performed an EKG. That’s when all hell broke loose. They stated that I needed a pacemaker as I was in stage 3 heart block. After getting the pacemaker, I felt much better and learned my heart stopped pumping blood to the body several times while in the ER. The ER doctor asked if I had Lyme disease. I did not know it at the time but quickly realized In discussions with them that I was suffering the symptoms for the past 6 weeks. Fever, aches, exhaustion, and rashes (not bullseye). I had even gone to my own doctor about it a few weeks prior. The hospital immediately started IV antibiotics and I spent 6 days in the CCU with a temporary pacemaker. Tests confirmed I in fact had Lyme disease.

    I am home now on IV therapy and pacemaker removed for the rest of the month and appear to be making a full recovery. I am thankful the ER doctor picked up on this immediately otherwise they would have implanted the pacemaker in my chest. The hospital care was excellent.

    1. That’s exactly what happened with me. Now my heart beat is always at 130. It’s been month since I was cured of Lyme and had my 3rd degree heart block but now my heart always feels like it’s pounding. I check it now and it is always so high I get confused and dizzy all the time. Sometimes I feel like I’m going into another heart block. At the moment, I have no insurance but soon I hopefully will. I keep looking on the internet to see if having a heart block can cause heart problems later on and I don’t really get straightforward answer. Do you have any ideas of what’s going on now with my heart? I’m actually scared it’s gonna stop next time.

  11. We desperately need studies for late stage Lyme and if treatment can still reverse the damage.
    I have also fought for years for tests and finally got one. I have both tach. And brac. And want to know if treatment now even after 7 years can save me from an eventual pacemaker…

  12. This is an excellent write-up of a condition that is under-reported. I had Lyme carditis in 2014. I was bitten by a tick in late September in Minnesota and was extremely ill a few days later, but never showed the classic rash at all. Finally, in mid-November, I was experiencing all of the symptoms above except chest pain.

    After a trip to the ER, I was told I was experiencing anxiety and I went on my business trip. Things didn’t get any better while I was gone. My heart palpitations were crazy and I nearly fainted a couple of times. My twin brother listened to my timeline and symptoms. He’s a nephrologist but had an internal medicine residency. He told me over the phone that I have Lyme carditis and that I should go to the ER and tell them that. The next morning I went, and two doctors ignored what I told them and did the same tests the last time I was there and told me I was fine.

    Then a 3rd doctor came into the room and was very interested. Asked many questions then finally said “I think your brother is right. We won’t know for sure for a day or two when the Lyme test results come back, but I want to admit you now and get IV antibiotics started immediately.”

    I spent two nights at the hospital and got better very quickly. The results came back the next day and I was indeed positive for Lyme. After being discharged from the hospital I had a PICC line for 2 weeks and administered antibiotics to myself each day at home and work. After completing IV antibiotics, I took an oral antibiotic daily for another 30 days. I am completely recovered to this day.

    What’s still somewhat disturbing to me is that if I didn’t have a brother who was a physician (and a damn smart one, to boot) I’m not sure this would have been caught before going Stage 2 or 3. Much more education is needed for physicians in regard to Lyme and other tick-borne illnesses. If not for my brother, I might have a pacemaker today, or even worse, I might be dead.

  13. I was treated for Lyme and other co-infections for over 2 1/2 years. My symptoms improved and I have been feeling better now for a few years. Recently I had surgery on my hand and was given an antibiotic prior to surgery. A few weeks later I started experiencing back, neck and shoulder pain. I went to my door and she did an EKG which was different from my last one a year ago. I then went to a heart doctor who performed an EcoCardiogram which did not show any other heart issues. Dr. said I have a left bundle branch block. He did not know what would have caused this. He wants me to have a Nuclear CatScan of my heart now. I have concerns about having this test. I have been reading that Lyme never leaves your body but symptoms improve with time and antibiotics. I am concerned now that Lyme is surfacing again and causing Lyme Carditis. Could this be possible? Especially where I am having neck, back pain and a few other symptoms again.

  14. Are there any studies that look into Late stage Lyme that can cause heart damage? That would be interesting as so many late stage Lyme patients have heart issues.. thank you for any information you can provide. Grant it, depending on age and personal history it could be other underlying issues that were brought to the forefront with the Lyme, but I would be curious if otherwise any research has shown long term heart damage by Lyme bacteria.

    1. Lyme carditis is believed to be relatively rare (only 4-10% of patients with Lyme are reported to have carditis and <1% to have an AV block), however the condition, while reversible, can be severe or fatal and heart tissue is one of the first places the bacteria will travel. Generally, cardiac symptoms seem to be more likely to show up early or not at all (or be undiagnosed) and patients with disseminated or late-stage Lyme present more often with neurologic than heart problems.

      That being said, Lyme carditis, like many aspects of Lyme, is still far from well understood and the low number of reported cases has limited the number of studies about the condition. There are no studies evaluating heart function in late stage Lyme patients that we are aware of. What we do know is that the condition is more common among younger males, a population not normally at elevated risk for heart disease. Also notable is the fact that the “telltale rash” [erythema migrans or EM] while not always present in all cases of a Lyme infection, is even less common in the reported cases of Lyme carditis.

      You may wish to consult the above links or those footnoted on this post for more information about published studies.

      Thank you for your interest.

    2. It’s hard to believe less than one percent have Lyme carditis. The reporting around this and the state of health care and information is less than adequate. I have first degree AV block and palpitations like crazy. Are the antibiotics working? Who knows – doctors don’t care.

  15. Would a simple EKG pick this up? I have severe chest pains for several years but my EKG is always fine. I have also had a cardiac ultrasound come back normal.

  16. I have had Lyme disease for over ten years. I am 40 year old woman who is disabled so how can I get more help with fighting this? Would love to be able to find out more on this disease. Thank You

    1. Michele, One place to start might be connecting with a local Lyme disease support group. offers a national directory of support groups in all 50 states. And the International Lyme and Associated Diseases Society (ILADS) offers a similar referral service for physicians and care providers familiar with the disease (both in the US and in many other countries). Unfortunately with this illness, there is an awful lot of self-advocacy required to get the care and attention needed. There is still shockingly little awareness and understanding. Best wishes.

  17. I had 3rd degree heart block last Dec. and had to have a pacemaker put in. The cause according to the cardiologist?? I did not fit the criteria. I tested for Lyme in hospital, it came back negative. I’ve been symptomatic for Lyme for years but test always came back negative. After my heart issue, I decided to get my own testing and went to Lyme Literate DR. It came back positive for Lyme antibodies along with other co-infections. My cardiologists still refuse to acknowledge my Lyme and tell me my heart is fine with Pacemaker, but I’m not so sure.. Is there any way to test for certain that my heart is damaged by Lyme carditis ?

    1. Unfortunately there really is no non-invasive test for Lyme carditis, however the standard treatment when diagnosed quickly is antibiotics and a temporary pacemaker. We would encourage you to continue to discuss your history and symptoms with your doctors and wish you the best of health.

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