Endocrinopathies and Atrial Fibrillation

Endocrine disorders lead to hormonal and metabolic changes, which also result in atrial remodelling, thereby progressively creating a substrate for atrial fibrillation (AF).

Adequate treatment of the endocrine disorder is essential for the prevention and management of AF.

In every newly diagnosed AF, thyroid function (TSH, fT4) must be assessed.

Amiodarone induces thyroid dysfunction in 15–20% of patients after 1–3 months of therapy:

it more frequently causes hypothyroidism than hyperthyroidism in a 4:1 ratio.

An amiodarone 300 mg bolus may transiently alter fT4 or TSH levels,

hormone levels return to baseline within 48 hours.
it does not cause clinically relevant hypothyroidism or hyperthyroidism (in patients without pre-existing thyroid disease).

Endocrine disorders associated with AF:

Illustration showing endocrinopathies including disorders of the pituitary gland, thyroid gland, pancreas, and adrenal glands as risk factors for atrial fibrillation with ECG documentation of arrhythmia.

Endocrine disorders associated with atrial fibrillation
Hypothyroidism Prevalence: 1% Diagnosis: fT4, TSH AF prevalence: 1% AF mechanism: Diastolic dysfunction → atrial dilatation and remodelling
Hyperthyroidism Prevalence: 1% Diagnosis: fT4, TSH AF prevalence: 10–25% AF mechanism: T4/T3 increase beta-adrenergic receptor sensitivity → atrial remodelling
Acromegaly Prevalence: 1/10 000 Diagnosis: Growth hormone (GH) AF prevalence: 7% AF mechanism: Atrial enlargement and fibrosis

Infographic illustrating endocrinopathies associated with atrial fibrillation, including diabetes mellitus, hyperthyroidism, hypothyroidism, acromegaly, primary hyperparathyroidism, primary hyperaldosteronism, and Cushing syndrome, with characteristic hormonal and metabolic changes and ECG documentation of atrial fibrillation.

Endocrine disorders associated with atrial fibrillation
Primary hyperaldosteronism Prevalence: 5–10% in hypertensive patients, 20–30% in resistant hypertension Diagnosis: Hypokalaemia, poorly controlled hypertension, renin AF prevalence: 5–15%, in resistant hypertension 15–25% AF mechanism: Hypertension and hypokalaemia → atrial dilatation and electrical remodelling
Diabetes mellitus (DM) Prevalence: 10% (DM2 = 90%, DM1 = 10%) Diagnosis: Fasting glucose, HbA1c AF prevalence: 5–15% AF mechanism: Hyperglycaemia → diastolic dysfunction → atrial dilatation and remodelling
Primary hyperparathyroidism Prevalence: 0.1% Diagnosis: Hypercalcaemia, hypophosphataemia, ↑ parathyroid hormone AF prevalence: 5–15% AF mechanism: Hypercalcaemia → electrical remodelling → ectopic activity + atrial remodelling
Cushing syndrome Prevalence: 1/100 000 (80% central, 20% peripheral) Diagnosis: ACTH, 24-hour urinary cortisol, dexamethasone test AF prevalence: 5–10% AF mechanism: Cortisol overproduction → hypertension, LV hypertrophy, atrial remodelling

Endocrinopathies and atrial fibrillation	Class
In every patient with newly diagnosed atrial fibrillation, the following are recommended: TSH, fT4 (thyroid parameters) Fasting glucose, HbA1c (diabetes mellitus) K (primary hyperaldosteronism) Ca, P (primary hyperparathyroidism)	I