Epidemiological studies show an excess vascular mortality associated with hyperthyroidism, even after radioiodine treatment, and in people aged under 50.1 2 Thyrotoxic cardiomyopathy is a distinct clinical entity with devastating clinical consequences. It can affect young people even in the absence of underlying cardiac disease.3 4 It often presents as heart failure. Most cases are reversible, with cardiac function improving after thyroid function returns to normal.4 5 6 7 However, in the acute setting, the severity of the illness may result in fatalities despite treatment.8 9 10 This represents an important exception to the general principle that β blockers should be used in most hyperthyroid patients with tachyarrhythmias.

We present the case of a young man with chronic hyperthyroid Graves’ disease, who was admitted to hospital with severe heart failure, rapid atrial fibrillation, and pneumonia and died despite resuscitation.