Clinical introduction A man in his 50s with sudden-onset chest pain and dyspnoea was transferred to the emergency room. He had a history of aortic valve replacement due to aortic regurgitation with a mechanical valve 6 years previously. Heart rate was 90 bpm, and blood pressure was too low to measure. In the emergency room, he presented with severe dyspnoea and a chest X-ray showed severe lung congestion (figure 1A). ECG showed complete left bundle branch block. His respiratory status rapidly worsened, and he went into cardiopulmonary arrest. After cardiopulmonary resuscitation, transthoracic echocardiography was performed (figure 1B, online supplementary video 1).

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Figure 1

(A) Chest X-ray. (B) Colour Doppler image from apical five-chamber view.

Question What is the most likely cause of the patient’s cardiopulmonary arrest?

1. Myocardial infarction in left main trunk

2. Aortic dissection

3. Prosthetic valve thrombosis

4. Prosthetic valve embolisation

5. Pulmonary embolism