Acute Myocarditis Associated with Legionella Infection: Usefulness of Layer-specific Two-dimensional Longitudinal Speckle-tracking Analysis

Pneumonia is the most commonly described manifestation of Legionella pneumophila infection (legionellosis), and extrapulmonary manifestations are uncommon. There are a few descriptions of acute myocarditis associated with legionellosis. We present a case of acute myocarditis in a patient admitted for legionellosis with multisystemic involvement (lung, heart, and kidney). Left ventricular (LV) dysfunction was documented by cardiac magnetic resonance (CMR) and two-dimensional speckle-tracking echocardiography; layer-specific strain analyses were performed, which allowed to differentiate subendocardial or subepicardial contractile impairment. Layer-specific strain analyses by echocardiography demonstrated impairment of subepicardial deformation in the inferolateral wall, which mirrored CMR findings, showing late gadolinium enhancement in the subepicardium of the same LV segments. After initiation of appropriate antibiotic therapy with levofloxacin, LV systolic function rapidly improved as assessed by both CMR and strain analyses, with concomitant normalization of both clinical and biochemical abnormalities. The basic mechanisms of myocardial involvement during legionellosis are unclear; we discussed our findings according to the limited available evidence.