A 58‐year‐old woman has been brought into A&E complaining of sudden onset of severe shortness of breath and some mild chest tightness whilst eating her breakfast. She has had similar symptoms related to exertion over the past few months, albeit much less severe. These had settled on resting. She has had type 2 diabetes for many years and is now managed with insulin. She smokes 10 cigarettes a day and has a strong family history of ischaemic heart disease.

Examination shows her to be clammy and distressed. She is apyrexial with a BP 90/40 mmHg, pulse 110 beats/min sinus tachycardia. There are no cardiac murmurs but a third heart sound is audible. Her jugular venous pressure (JVP) is raised. The chest sounds rather wheezy. Her respiratory rate is 28 breaths/min, and SpO₂ 86% with 4 L/min oxygen.

Her ECG and chest X‐ray are shown in Fig. 0005.

Fig. 0005.