Clinical introductionA man in his 60s with no medical history presented with sudden-onset, severe interscapular pain. He was in circulatory shock with a blood pressure of 65/30 mm Hg, heart rate of 115 beats per minute, respiratory rate of 32 breaths per minute and a room air oxygen saturation of 89%. Examination demonstrated weak peripheral pulses, an elevated jugular venous pressure, faint dual heart sounds, no cardiac murmurs and bilateral lung crepitations. An ECG was recorded which showed a broad QRS (figure 1A). There were no previous ECGs to compare this with. In view of his presentation with acute-onset interscapular pain, CT of the aorta was organised by the emergency department clinicians (figure 1B–D). After the CT result was obtained, the on-call cardiologist was contacted and a bedside echocardiogram performed. This demonstrated severe left ventricular systolic dysfunction with akinesia of the apex and lateral walls. The patient was then transferred to the catheter laboratory for an emergency invasive coronary angiogram.Figure 1ECG and CT images at presentation (A) 12 lead ECG. (B) Contrast enhanced CT aorta - coronal view. (C) Contrast enhanced CT aorta - axial view. (D) CT aorta showing 4 chamber view of the heart.What is the most likely diagnosis?Pulmonary embolism.Aortic dissection.Acute myocardial infarction.Cardiac tamponade.