From the Guidelines
Yes, hypothyroidism can trigger arrhythmias, particularly ventricular arrhythmias, due to the prolongation of the QT interval 1.
Mechanism and Treatment
- The underlying mechanism is thought to be related to the prolongation of the QT interval, which can increase the risk of ventricular arrhythmias, including ventricular tachycardia (VT) and sudden cardiac death (SCD) 1.
- Thyroxin replacement therapy is usually effective in correcting this abnormality and preventing further arrhythmias.
- In emergency situations, antiarrhythmic drugs such as procainamide have been used successfully to manage arrhythmias in patients with hypothyroidism 1.
Clinical Considerations
- Patients with hypothyroidism should be monitored closely for the development of arrhythmias, particularly those taking medications that can affect thyroid function, such as amiodarone 1.
- New onset atrial fibrillation or exacerbation of ventricular arrhythmias should prompt a re-evaluation of thyroid status 1.
From the Research
Hypothyroidism and Arrhythmias
- Hypothyroidism can trigger arrhythmias, although it is more commonly associated with sinus bradycardia, low QRS complexes, prolonged QT interval, and conduction blocks 2.
- A case study reported a patient with severe hypothyroidism who presented with supraventricular tachycardia, which disappeared after thyroxine replacement therapy, suggesting a possible link between hypothyroidism and arrhythmias 2.
- However, a prospective study found that thyroid replacement therapy did not trigger an increase in arrhythmia frequency in patients with hypothyroidism, except in rare cases with baseline atrial premature beats 3.
Prevalence of Arrhythmias in Hypothyroidism
- A case-control study found a higher prevalence of ventricular tachycardia and any ventricular arrhythmia in hypothyroid patients compared to euthyroid controls 4.
- A review article suggested that patients with untreated overt clinical or subclinical thyroid dysfunction, including hypothyroidism, are at increased risk of arrhythmia, particularly ventricular arrhythmia 5.
- An animal study found that both hypothyroidism and hyperthyroidism increased atrial fibrillation inducibility in rats, highlighting the importance of normal thyroid hormone levels in maintaining cardiac electrophysiology 6.
Key Findings
- Hypothyroidism may increase the risk of ventricular arrhythmias, including ventricular tachycardia 4, 5.
- Thyroid replacement therapy can improve cardiac function and reduce the risk of arrhythmias in patients with hypothyroidism 2, 3.
- Normal thyroid hormone levels are essential for maintaining normal cardiac electrophysiology and preventing cardiac arrhythmias 6.