Acute severe mitral regurgitation mimicking pneumonia: the diagnostic value of echocardiography.

Acute hypoxaemic respiratory failure is frequently attributed to primary pulmonary pathology, particularly in the presence of radiographic abnormalities and inflammatory markers. Cardiac conditions, however, may present with similar features and lead to diagnostic error. We report the case of a man in his early 60s admitted with acute hypoxaemic respiratory failure, initially diagnosed with severe community-acquired pneumonia on the basis of unilateral chest opacity and an apparent inflammatory response. Despite empirical antibiotic therapy, his respiratory status deteriorated. Bedside echocardiography identified acute severe mitral regurgitation due to rupture of the posterior mitral leaflet chordae tendineae. Targeted medical management was initiated, followed by definitive surgical repair with full clinical recovery. This case highlights the potential for acute valvular disease to mimic pulmonary infection and the importance of early echocardiographic assessment in patients with unexplained respiratory failure.