Increased Admissions Due to Cardiac Complications of Thyrotoxicosis in Māori

As thyrotoxicosis is a risk factor for atrial fibrillation, current guidelines recommend measuring a thyroid-stimulating hormone level in patients with this disorder. Hyperthyroidism may also be associated with other heart diseases including cardiac ischaemia and cardiac failure. Currently, the prevalence of thyrotoxicosis in cardiac admissions in the absence of a rhythm disorder is unknown.

The aims of this study were: 1) to calculate the prevalence of admissions for thyrotoxicosis-associated cardiac disease, 2) determine the type of cardiac disease i.e. dysrhythmic, ischaemic or cardiac failure, and 3) to assess whether Māori are over-represented amongst patients admitted to hospital with cardiac complications of thyrotoxicosis.

A retrospective review of admissions with both thyrotoxicosis and cardiac disease from 1 January 2005 to 31 December 2012 inclusive.

Seventy-two patients were identified as being admitted for a cardiac complication of thyrotoxicosis, giving a mean of nine admissions per year. Dysrhythmia was the cause for admission in 32 patients, ischaemia in 12, cardiac failure in 11 and mixed cardiac disease in 17. Graves' disease and amiodarone-induced were the most common causes of the thyrotoxicosis (25 and 19 cases, respectively). Of the cohort 26 (36.1%) were Māori (compared to 16.8% of all cardiac admissions over the same period). Māori were more likely to present with cardiac failure than non-Māori (57.7% vs. 26.1%, p=0.008 respectively).

Māori are over-represented amongst patients admitted with cardiac complications of thyrotoxicosis and more often present with cardiac failure than non-Māori. Measurement of thyroid function should be considered in patients presenting not only with atrial fibrillation but also in patients presenting with cardiac failure, particularly if they are Māori.