Lyme Carditis: Correlation of CMR Findings with Clinical Conduction Block

Presenting Author(s)

• 

  Gina E. Lazzara, MD

  Advanced Imaging Fellow
  Vanderbilt University Medical Center
  Nashville, Tennessee, United States

Primary Author(s)

• 

  Gina E. Lazzara, MD

  Advanced Imaging Fellow
  Vanderbilt University Medical Center
  Nashville, Tennessee, United States

Co-Author(s)

• MF

  Mohammed Faluk, MD

  Clinical Fellow
  Vanderbilt University Medical Center, United States
• JS

  Joseph R. Starnes, MD

  Clinical Fellow
  Vanderbilt University Medical Center, United States
• LL

  Luke Laws, MD

  Clinical Fellow
  Vanderbilt University Medical Center, United States
• JW

  John A. Wells, IV, MD

  Assistant Professor of Clinical Medicine
  Vanderbilt University Medical Center
  Nashville, Tennessee, United States
• 

  Bruno B. Lima, MD, PhD

  Assistant Professor of Medicine
  Vanderbilt University Medical Center
  Nashville, Tennessee, United States
• JD

  Jeffrey M. Dendy, MD

  Assistant Professor of Medicine
  Vanderbilt University Medical Center
  Brentwood, Tennessee, United States
• SH

  Sean G. Hughes, MD, FSCMR

  Associate Professor of Clinical Medicine and Radiology Director, Cardiac MRI and Advanced Cardiac Imaging Fellowship
  Vanderbilt University Medical Center
  Brentwood, Tennessee, United States
• 

  Tania Ruiz M., MD

  Assistant Professor of Medicine
  Vanderbilt University Medical Center
  Nashville, Tennessee, United States

Description of Clinical Presentation: We present a case of a 30-year-old male who presented with presyncope after two weeks of flu-like symptoms and abdominal rash, followed by two days of left-sided facial paralysis after hiking in the American Northeast. His ECG showed 2:1 atrioventricular (AV) block with marked PR prolongation and ventricular rate in the 40s (Figure 1). Laboratory testing revealed elevated C-reactive protein to 76.3 mg/L (normal < 5.0) and positive Lyme serologies (positive IgG and IgM). High-sensitivity troponin levels, complete blood count, and metabolic panel were within normal limits. He was initiated on intravenous ceftriaxone 2g daily given disseminated Lyme disease, and a temporary permanent pacemaker (TPM) was placed after obtaining cardiac magnetic resonance imaging (CMR). After seven days of antibiotics, the AV block had resolved. TPM was subsequently removed, and the patient was discharged with 28 days of oral doxycycline 100 mg twice daily with plans for follow-up CMR imaging to monitor cardiac recovery.

Diagnostic Techniques and Their Most Important Findings: CMR revealed moderately dilated left ventricle with mildly reduced systolic function (ejection fraction 46%) and a severely dilated right ventricle with moderately reduced systolic function (ejection fraction 37%). Dense late gadolinium enhancement (LGE) was present in the subendocardial aspect of the basal inferior and inferoseptal walls, extending to the level of the atrioventricular junction (Figure 2). Quantitative mapping showed global elevation, predominately at the basal inferoseptum, of the myocardial T1/T2, and the extracellular volume (Figure 3). The clinical and imaging findings were consistent with inflammatory cardiomyopathy due to Lyme carditis.

Learning Points from this Case: Lyme carditis is a rare but serious complication of Lyme disease. Although fewer than 10% of patients develop cardiac involvement, nearly 90% of those patients will present with AV block^{2, 5}. Symptoms are often nonspecific, including shortness of breath, palpitations, dizziness, and syncope⁴. Lyme carditis is often clinically insidious, but may manifest with acute myocarditis, pericarditis, myopericarditis, or endocarditis². This case highlights the importance of CMR in assisting the timely diagnosis of acute inflammatory cardiomyopathies, as arrhythmias may be transient and resolve after appropriate treatment for the underlying etiology^{1, 3}. In this case, CMR findings were critical in providing supportive therapy, and supporting treatment of AV block with temporary pacing rather than implantation of a permanent system. This case also illustrates the physiologic correlation between LGE near the AV node and clinical heart block in Lyme carditis.

Figure 1
Figure 2
Figure 3