Synergistic Lyme Carditis and Coxsackievirus A Myocarditis Presenting With Fulminant Heart Failure.

BACKGROUND

Myocarditis typically results from single viral pathogens, most commonly Coxsackievirus B. Concomitant bacterial-viral myocarditis remains exceptionally rare.

CASE SUMMARY: A healthy 28-year-old man developed progressive heart failure over 2 months, culminating in cardiogenic shock. Echocardiography revealed severe biventricular dysfunction (ejection fraction: 15%-20%) with complete heart block. Serologic testing confirmed dual infection with Lyme disease and Coxsackievirus A. Despite targeted antibiotic therapy, conduction did not recover, requiring cardiac resynchronization therapy with defibrillator implantation.

DISCUSSION: This represents the first reported case of simultaneous Coxsackievirus A myocarditis and Lyme carditis. Synergistic inflammatory responses between viral cytotoxicity and bacterial immune activation created fulminant heart failure exceeding what either pathogen typically causes alone.

TAKE-HOME MESSAGES: Dual infectious myocarditis can produce devastating cardiac consequences through synergistic inflammatory mechanisms that exceed the effects of single pathogens. Young patients with fulminant myocarditis and conduction abnormalities warrant a comprehensive infectious evaluation for overlapping etiologies.