A 70-year-old man developed Lyme carditis with heart block but no rash, no tick bite, and no classic Lyme symptoms. The case demonstrates why cardiac patients in endemic areas need Lyme testing even when typical signs are absent.

The Diagnostic Challenge

The authors describe a 70-year-old male who presented to the hospital without any typical Lyme disease symptoms, but exhibited generalized symptoms of progressive orthopnea and dyspnea on exertion.

His medical history complicated the picture: hypertension and calcific aortic stenosis. Multiple conditions could explain his cardiac symptoms. Nothing about his presentation screamed “Lyme disease.”

His lab results were “significant for an increased erythrocyte sedimentation rate of 136, white blood cell count of 16.6, hemoglobin of 9.3, creatinine of 2.6, and normal liver enzymes. Troponins were negative but his brain natriuretic peptide was elevated at 877.”

His admitting EKG was significant for bradycardia with a heart rate in the mid-40s and a first-degree AV block.

What Doctors Considered First

Clinicians developed a differential diagnosis based on his known medical conditions and lab findings:

• Anemia (hemoglobin 9.3)
• Progressive kidney disease (creatinine 2.6)
• Congestive heart failure exacerbation (elevated BNP)
• Worsening aortic stenosis
• Pneumonia

All reasonable considerations given his presentation. But something made clinicians expand their thinking.

“Due to the prevalence of Lyme disease in the northeast and the patient’s symptomatology, a tick panel was ordered which came back positive for Lyme,” the authors wrote.

The decision to test for Lyme disease despite absent classic symptoms saved this patient’s life.

Atypical Presentation of Lyme Carditis

“We report a case of a 70-year-old male with Lyme disease presenting with a second-degree, Mobitz type 1 AV block.”

The progression from first-degree to second-degree AV block demonstrates the rapid fluctuation characteristic of Lyme carditis. Even patients who appear stable on admission can deteriorate quickly as spirochete-induced inflammation affects the cardiac conduction system.

This case diverges from the typical Lyme carditis presentation in several ways:

• No erythema migrans rash – Only 40% of carditis patients recall having a rash
• No recalled tick bite – Most patients don’t remember being bitten
• No classic Lyme symptoms – No fever, no joint pain, no neurologic complaints
• Older patient with comorbidities – Competing diagnoses obscured the Lyme etiology
• Isolated cardiac manifestation – Heart block was the sole presenting feature

Yet the geographic context mattered. In an area endemic for Lyme disease, unexplained AV block – particularly in a patient without structural heart disease adequate to explain the conduction abnormality – warrants Lyme testing.

Treatment and Recovery

The patient was treated with IV ceftriaxone (Rocephin) and oral doxycycline. He had complete resolution of symptoms with normal sinus rhythm and no AV block.

This dramatic response to antibiotics confirms the Lyme diagnosis and demonstrates the reversibility of cardiac conduction abnormalities when treatment begins promptly. Had clinicians dismissed the possibility of Lyme disease based on absent typical symptoms, this patient might have progressed to complete heart block, required permanent pacing, or died.

Why Geographic Context Matters

“This incidence shows the importance of having a Lyme disease diagnosis when regionally appropriate for patients who may present with no other signs or symptoms other than an AV block.”

The authors emphasize regional awareness: “In highly endemic areas such as the northeast and Midwest United States, early recognition and treatment of Lyme disease is important for the prevention of long-term complications of disseminated infection.”

This case occurred in the northeast. The patient’s geographic location lowered the threshold for Lyme testing despite absent classic symptoms. This regional thinking prevented a diagnostic delay that has proven fatal in other cases.

Clinical Takeaways

This case challenges the assumption that Lyme carditis presents with recognizable Lyme disease features. In my practice, I’ve learned that cardiac manifestations can be the isolated presentation – no rash, no recalled exposure, no systemic symptoms that trigger Lyme disease consideration.

The key lessons:

1. Lyme carditis doesn’t require typical symptoms – Heart block can occur without rash, fever, or other classic findings
2. Geographic location guides testing – Endemic area residence warrants Lyme testing for unexplained cardiac conduction abnormalities
3. Comorbidities don’t exclude Lyme disease – Older patients with multiple medical conditions can still develop Lyme carditis
4. AV block in the absence of adequate structural explanation should trigger Lyme testing – Particularly in younger patients or those from endemic areas
5. Dramatic response to antibiotics confirms diagnosis – Complete resolution of heart block indicates reversible, infection-driven pathology

Frequently Asked Questions

Can you have Lyme carditis without a rash?

Yes. Only 40% of Lyme carditis patients recall having an erythema migrans rash. Absence of rash does not rule out Lyme disease, particularly when cardiac symptoms occur in endemic areas.

Can Lyme carditis be the only symptom of Lyme disease?

Yes. This patient had isolated cardiac manifestations with no fever, no joint pain, no neurologic symptoms. Lyme carditis can be the sole presentation of Lyme disease.

Should doctors test for Lyme disease in patients with unexplained heart block?

Yes, particularly in endemic areas. Even without typical Lyme symptoms, unexplained AV block warrants Lyme testing when patients live in or have traveled to regions where Lyme disease is prevalent.

Do older adults get Lyme carditis?

Yes. While young adults ages 15-45 are most commonly affected, Lyme carditis can occur at any age. Older patients often have competing diagnoses that obscure the Lyme disease etiology.

Can heart block from Lyme disease be cured?

Yes. This patient achieved complete resolution with antibiotics – normal sinus rhythm with no AV block. Most Lyme carditis cases resolve completely when treated promptly.