From the Research
For a hyperthyroid patient with paroxysmal supraventricular tachycardia (PSVT), a reasonable starting dose of propranolol would be 10-20 mg orally three to four times daily, with careful titration based on response, as recommended by recent guidelines and studies 1. The dose can be gradually increased to 40-80 mg three to four times daily as needed and tolerated. In acute settings, propranolol can be administered intravenously at 1-3 mg given slowly over 2-5 minutes, not exceeding 1 mg/minute, with careful monitoring of heart rate and blood pressure. Some key points to consider when treating hyperthyroid patients with PSVT include:
- Propranolol is particularly beneficial in hyperthyroid patients because it addresses both the underlying sympathetic overactivity from hyperthyroidism and helps control the PSVT.
- The medication works by blocking beta-adrenergic receptors, reducing heart rate, cardiac output, and AV nodal conduction.
- Patients should be monitored closely for bradycardia, hypotension, and bronchospasm, especially during initial dosing.
- Lower starting doses may be appropriate in patients with hepatic impairment, as propranolol undergoes extensive first-pass metabolism in the liver.
- Treatment should continue until the hyperthyroidism is adequately controlled with anti-thyroid medications, as the tendency for arrhythmias often improves once euthyroidism is restored, as supported by studies such as 2 and 3. It's also important to note that while other medications like verapamil may be considered, propranolol remains a preferred option due to its effectiveness in managing both the arrhythmia and the symptoms of hyperthyroidism, as discussed in 1 and other recent studies.