Clinical introduction A 77-year-old female was referred for evaluation of an episode of syncope while eating breakfast. There was no history of fall, syncope, prodrome, dyspnoea, chest discomfort or palpitations. Medical history was notable for hyperlipidaemia and treated hypertension. Blood pressure was 140/90 mm Hg, pulse 85  beats per minute (BPM). No murmurs were present on cardiac examination. ECG revealed normal sinus rhythm with left ventricular (LV) hypertrophy (see online supplementary figure S1). Holter monitor demonstrated rare premature ventricular complexes (<1% of beats), without heart block or ventricular tachycardia. Transthoracic echocardiogram is shown in figure 1.

Question Which of the following is the explanation for the flow indicated by the yellow arrow?

1. Aortic stenosis

2. Coronary artery flow, indicative of coronary fistula

3. Hypertrophic cardiomyopathy with apical pouch

4. Hypertensive heart disease

5. Mitral stenosis