A 48-year-old gentleman presented with history of progressive dyspnea on exertion of 2-year duration. Transthoracic echocardiography revealed a thickened noncalcific mitral valve with severe mitral stenosis, with a mitral valve area of 0.5 cm² (A and B, Online Videos 1 and 2). The left atrium was aneurysmally dilated with intense spontaneous echocardiographic contrast (“smoke”) swirling within the left atrium. The dense echogenic blood in the left atrium flowing through the stenotic mitral valve gave rise to an interesting echocardiographic appearance akin to a “smoking” mitral valve (C, Online Video 3). Transesophageal echocardiography had revealed a clot in the roof of the left atrium. He was subsequently referred for open surgical repair of the mitral valve and clot removal.

Spontaneous echocardiographic contrast is a characteristic echocardiographic phenomenon with a distinct smoke-like swirling pattern of blood flow seen in conditions with slow blood flow or stasis and is an indicator of increased thromboembolic risk.