Another cardiac manifestation of Lyme myocarditis
The list of cardiac complications from Lyme disease continues to grow. Now, you can add another manifestation to the list -- isolated left bundle branch block (LBBB), according to Cunha from the Infectious Disease Division at Winthrop-University Hospital. 
A 30-year-old man presented to the ER with “a pulse of 53/min and annular macular rash located over the anterior and posterior aspect of the left chest wall,” writes Cunha. Laboratory evidence confirmed Lyme disease by ELISA and both an IgG and IgM western blot. His ejection fraction was slightly reduced at 50%. The rash and LBBB resolved quickly with 2 weeks of doxycycline.
Lyme carditis is not new, Cunha points out. “The first reported cases of Lyme carditis was in 1980, when Steere and colleagues described 20 North American cases.” Cunha and colleagues reviewed the growing range of cardiac manifestations that have since been published and include:
• atrioventricular block including complete or high-grade block
• alternation right bundle branch block and left bundle branch block
• diffuse ST segment and T wave changes on electrocardiogram
• left ventricular systolic dysfunction
• congestive heart failure
The authors remind readers of the importance of prompt medical attention. “The conduction disturbances associated with Lyme carditis, can be variable and rapidly fluctuating,” writes Cunha.
[bctt tweet=”The list of cardiac symptoms caused by #Lyme disease continues to grow. ” username=”DrDanielCameron”]
“On occasion, patients may progress from having a prolonged PR interval to complete heart block within minutes, with alternating tachycardias and bradycardias as the signs most strongly suggestive of cardiac involvement.” He also adds, “Most conduction abnormalities are reversible but the time course to recovery is unpredictable.”
It is encouraging that doctors are beginning to better understand the growing complexity of cardiac manifestations of Lyme disease.
- Cunha BA, Elyasi M, Singh P, Jimada I. Lyme carditis with isolated left bundle branch block and myocarditis successfully treated with oral doxycycline. IDCases. 2018;11:48-50.