When Fatigue and Muscle Pain Signal Heart Trouble: A Lyme Disease Case Study

Table of Contents

• Background: Why This Case Matters
• The Patient's Story: Symptoms and Medical Journey
• Medical History and Risk Factors
• Examination and Test Results
• Possible Diagnoses Considered
• Final Diagnosis and Treatment
• Understanding Lyme Disease and Testing
• The Patient's Experience
• What This Means for Patients
• Limitations of This Case
• Recommendations for Patients
• Source Information

Background: Why This Case Matters

Lyme disease affects approximately 476,000 Americans each year according to CDC estimates, making it the most common vector-borne illness in the United States. This case demonstrates how Lyme disease can sometimes present with serious heart complications that may be mistaken for other conditions. The patient's journey through multiple healthcare facilities before receiving the correct diagnosis illustrates the diagnostic challenges that can occur with Lyme disease, particularly when patients don't recall tick bites or recognize early symptoms.

This case is especially relevant as Lyme disease continues to expand its geographic range due to climate change and other factors. Patients who spend time outdoors in endemic areas need to be aware of both typical and unusual presentations of this disease. The heart complications described here, while occurring in only about 1% of Lyme disease cases, can be serious if not recognized and treated promptly.

The Patient's Story: Symptoms and Medical Journey

A 32-year-old woman sought medical attention for severe fatigue and muscle pains (myalgias). Her health problems began two and a half years earlier when she developed fatigue, headaches, muscle pain, and "brain fog" after being infected with SARS-CoV-2 (the virus that causes COVID-19). At that time, she consulted neurology, immunology, and rheumatology specialists at another hospital, but extensive testing revealed normal results.

Her blood tests showed normal levels of electrolytes, thyroid function, liver enzymes, bilirubin, alkaline phosphatase, C-reactive protein, and ferritin. Complete blood count and kidney function tests were also normal. Tests for cytomegalovirus, Epstein-Barr virus, ehrlichia, anaplasma, and Borrelia burgdorferi (the bacteria that causes Lyme disease) were negative. An MRI of her head was normal as well.

Over the next two years, she found some relief through acupuncture and herbal supplements. Five weeks before her current presentation, she was reinfected with SARS-CoV-2 but recovered after five days. Nine days before admission, she developed neck tightness and pain after lifting heavy objects, with pain radiating to her head and shoulder blades.

Six days before admission, her primary care physician found no abnormalities on examination and recommended ibuprofen, magnesium, acupuncture, and massage. When her pain persisted and began radiating down her right arm three days later, with severe fatigue developing, she went to an emergency department.

Medical History and Risk Factors

The patient's medical history included umbilical hernia repair, hyperemesis gravidarum (severe nausea during pregnancy), anxiety, and mild chronic gastritis. Her medications included magnesium supplements, probiotics, and a supplement containing turmeric, animal liver extract, and milk thistle.

Notably, she had not been vaccinated against SARS-CoV-2. She lived with her husband and two children in a forested area in New England where they raised rabbits and sheep. She regularly participated in outdoor activities including hiking, camping, and yoga. She vaped and had a history of tobacco and marijuana use.

Her family history included hypertension, a patent foramen ovale (a heart opening that usually closes after birth), and stroke in her maternal grandmother; hypertension in her maternal grandfather; colorectal cancer in her paternal grandmother; and Kawasaki's disease in one of her children.

Examination and Test Results

During her first emergency department visit, her temperature was 36.8°C (98.2°F), heart rate 50 beats per minute, and blood pressure 109/55 mm Hg. She had full neck motion but tenderness on the right side of her upper neck and back. A cervical spine X-ray was normal. She received intravenous ketorolac, oral methocarbamol, and transdermal lidocaine, plus a tapering dose of oral methylprednisolone.

Two days later, her back and neck pain resolved but fatigue worsened and muscle pains developed. She experienced palpitations, an irregular pulse, and waxing/waning lower chest pain described as tightness that was both pleuritic (worsened by breathing) and positional. She rated this pain 5/10 in severity.

At a second emergency department, her temperature was 36.3°C (97.3°F), heart rate 58 beats per minute, blood pressure 124/79 mm Hg, and oxygen saturation 100%. Blood tests showed normal electrolytes and troponin I (a heart enzyme), but elevated alanine aminotransferase (170 U/L, normal 7-40), aspartate aminotransferase (104 U/L, normal 8-30), and d-dimer (1760 ng/mL, normal <520).

Electrocardiography (ECG or EKG) showed first-degree atrioventricular block (a delay in electrical conduction through the heart) with a heart rate of 55 beats per minute. Chest X-ray and liver ultrasound were normal. CT angiography of the chest showed no evidence of pulmonary embolism (blood clots in lungs), with normal heart and lungs.

At Massachusetts General Hospital, her examination revealed an irregularly irregular cardiac rhythm, temperature of 36.3°C (97.3°F), heart rate of 52 beats per minute, and blood pressure of 140/76 mm Hg. Blood tests showed elevated alanine aminotransferase (89 U/L, normal 7-33) and NT-proBNP (604 pg/mL, normal <450), a marker of heart strain. d-dimer was slightly elevated at 436 ng/mL (normal <500).

An ECG showed Mobitz type I second-degree atrioventricular block along with first-degree atrioventricular block with a PR interval of 240 msec (normal 120-200). There were also Q waves in the inferior leads, which can indicate previous heart damage.

Possible Diagnoses Considered

The medical team considered multiple possible explanations for her symptoms:

• COVID-19 complications: Including heart inflammation (pericarditis or myocarditis) or multisystem inflammatory syndrome, but her normal inflammatory markers made this less likely
• Pulmonary embolism: Blood clots in the lungs, but CT angiography ruled this out
• Acute coronary syndrome: Heart attack or related conditions, but unlikely given her age and normal troponin
• Cardiomyopathy: Heart muscle disease, but heart size was normal on imaging
• Infections: Including brucellosis or tularemia from animal exposure, but these were less likely
• Lyme carditis: Heart complications from Lyme disease, which became the leading diagnosis given her cardiac conduction abnormalities, rural residence, and outdoor activities

Final Diagnosis and Treatment

Lyme carditis was identified as the most likely diagnosis. The medical team immediately performed Lyme disease blood testing and started empirical antibiotic therapy with intravenous ceftriaxone.

Her heart conduction abnormalities progressed despite treatment initially. On hospital day 1, her PR interval worsened to 350 msec. On hospital day 2, she developed complete atrioventricular block (third-degree heart block), where the electrical signals between the upper and lower chambers of the heart completely fail to communicate.

Fortunately, this complete heart block was transient and resolved within hours without requiring a temporary pacemaker. The team considered placing a temporary transvenous pacing wire but held off since she remained asymptomatic and maintained adequate cardiac output.

Understanding Lyme Disease and Testing

Lyme disease is caused by the bacterium Borrelia burgdorferi, transmitted through bites from infected Ixodes scapularis ticks in the northeastern United States. The disease typically progresses through three stages:

1. Early localized disease: Occurs 3-30 days after a tick bite, characterized by erythema migrans (the bull's-eye rash) and flu-like symptoms
2. Early disseminated disease: Develops weeks to months after infection, with systemic symptoms including potential heart and neurological involvement
3. Late disseminated disease: Occurs months to years later, often causing arthritis in large joints

Up to 40% of Lyme disease patients don't recall a tick bite, and many don't remember having the characteristic rash. Serologic testing for Lyme disease follows a two-tier approach:

• Standard two-tiered testing (STTT): An enzyme immunoassay followed by an immunoblot assay
• Modified two-tiered testing (MTTT): An enzyme immunoassay followed by a second enzyme immunoassay with different properties

Both approaches have good clinical performance for detecting later stages of Lyme disease, with sensitivity approaching 100% for tertiary infection. In this patient, the enzyme immunoassay was positive, confirmed by an immunoblot assay that was positive for both IgM and IgG antibodies.

The Patient's Experience

On her third hospital day, the patient remembered to show her doctor a photograph she had taken three weeks earlier of a rash on her arm. She reported having similar rashes all over her body at that time. This photograph showed an erythematous (red), circular, macular rash consistent with erythema migrans—the characteristic bull's-eye rash of Lyme disease.

This retrospective recognition of the classic Lyme disease rash confirmed the diagnosis and highlighted how patients may not initially connect such symptoms with their later illness, especially when the rash appears in hard-to-see areas or when multiple rashes are present.

What This Means for Patients

This case illustrates several important points for patients:

• Lyme disease can cause serious heart complications, including various degrees of heart block
• These cardiac issues typically improve with appropriate antibiotic treatment
• Patients may not recall tick bites or recognize early symptoms like the characteristic rash
• People who live in or visit wooded areas in Lyme-endemic regions should be particularly aware of these possibilities
• Cardiac manifestations of Lyme disease usually respond well to antibiotics, often avoiding the need for permanent pacemakers

The transient nature of the complete heart block in this case demonstrates how Lyme carditis often resolves with appropriate treatment, unlike many other causes of heart block that may require permanent pacemaker implantation.

Limitations of This Case

While this case provides valuable insights, it has several limitations:

• This is a single case report, so the findings cannot be generalized to all Lyme disease patients
• The patient had complex medical history including previous COVID-19 infections that might have influenced her presentation
• She used various supplements and treatments that could have modified her symptoms or test results
• The diagnosis was confirmed retrospectively after she recalled and produced photographic evidence of the rash
• Some testing for other tick-borne illnesses (like babesia and anaplasma) was negative, but not all possible infections were ruled out

Recommendations for Patients

Based on this case, patients should consider the following:

1. Prevention: Use tick prevention measures when spending time outdoors in endemic areas, including protective clothing, tick repellents, and thorough tick checks after outdoor activities
2. Awareness: Learn to recognize the erythema migrans rash, which may not always have a classic bull's-eye appearance and can occur anywhere on the body
3. Documentation: Take photographs of any unusual rashes or skin changes to show healthcare providers if symptoms develop later
4. Medical history: Inform doctors about outdoor activities, animal exposures, and any rashes—even those that seemed minor or resolved quickly
5. Follow-up: Seek prompt medical attention if experiencing unexplained fatigue, muscle pains, heart palpitations, or other concerning symptoms after potential tick exposure

Patients should know that most cases of Lyme disease are successfully treated with antibiotics, especially when diagnosed early. Even when complications like Lyme carditis develop, appropriate treatment typically leads to full recovery.

Source Information

Original Article Title: Case 24-2025: A 32-Year-Old Woman with Fatigue and Myalgias

Authors: Deborah Gomez Kwolek, MD; Julian S. Haimovich, MD; Marc D. Succi, MD; David M. Dudzinski, MD; Sarah E. Turbett, MD

Publication: The New England Journal of Medicine, 2025;393:799-807

DOI: 10.1056/NEJMcpc2312739

This patient-friendly article is based on peer-reviewed research from a case report published in The New England Journal of Medicine. Case Reports from Massachusetts General Hospital provide detailed educational accounts of interesting patient cases that offer valuable learning points for both medical professionals and patients.