A tropical electrocardiogram wave

A man in his 70s on holiday from Ghana presented to the emergency department with a one week history of lethargy. On arrival he was bradycardic (heart rate 20 beats/min) and hypotensive (88/55 mm Hg).

He had a history of cardiac failure (left ventricular ejection fraction 35%), atrial fibrillation, chronic kidney disease stage G3aA3, hypertension, and stroke.

Over the past six months his daily dietary intake had comprised a large proportion of tropical fruits (including mangoes, bananas, and pineapples) and two litres of fresh orange juice. He was taking amlodipine 10 mg daily, allopurinol 100 mg daily, atorvastatin 20 mg daily, bumetanide 2 mg twice a day, carvedilol 6.25 mg twice a day, quinine sulphate 200 mg every night, ramipril 2.5 mg daily, spironolactone 25 mg daily, and warfarin.

Table 1 shows the results of electrocardiography (fig 1), ultrasonography, and key laboratory tests on admission to the emergency department.