Acute myocarditis and dilated cardiomyopathy in Lyme disease

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