Heart involvement of
Lyme disease occurs in about 4-10% of patients with
Lyme borreliosis. The most common manifestation is acute, self-limiting
Lyme carditis, which manifests mostly as transient conduction disorders of the heart, pericarditis and myocarditis. Laboratory tests (ELISA, immunoblotting and PCR) usually have limited sensitivity and specificity, and criteria of performance and interpretation have not yet been fully evaluated. Therefore the laboratory evidence should only be interpreted in conjunction with other clinical and diagnostic features. Recently there has been convincing evidence published that long standing dilated cardiomyopathy in many cases is associated with a chronic Borrelia burgdorferi (BB) infection. Several studies showed a higher prevalence of BB antibodies in patients with severe heart failure in endemic areas (e.g., 26% versus 8% in healthy individuals). The isolation of spirochetes from the myocardium gave further evidence that BB may cause chronic heart muscle
disease. In several studies antimicrobial treatment showed an improvement of the left ventricular function in patients with dilated cardiomyopathy associated with BB. However the duration of dilated cardiomyopathy before treatment plays an important part in the clinical outcome of BB-associated chronic myocarditis.