Beta Blockers

●  Brand Names: Cardioselective Beta Blockers are Atenolol (Tenormin), Metoprolol (Lopressor), Nebivolol (bystolic), Bisoprolol; Non-cardioselective beta blockers are propranolol (Inderal), nadolol, sotalol.

●  Indications: low-dose beta-blockers are especially recommended in POTS patients with ‘hyperadrenergic’ subtype associated with sinus tachycardia >120 bpm on standing

●  Contraindications: Beta-blockers may aggravate orthostatic intolerance in low-BP phenotype, asthma and paroxysmal chest pain.

●  Mechanism of Action: Beta adrenergic receptor antagonists can blunt elevations in heart rate in those with POTS. Those that are cardioselective (such as atenolol) block the effects of adrenaline (epinephrine) by blocking beta-1 adrenergic receptors and therefore have fewer effects on other parts of the body. Non-Cardioselective beta blockers (such as propranolol) block both beta-1 (heart) and beta-2 (lungs, blood vessels, etc.) adrenergic receptors. Propranolol and metoprolol have been studied the most in POTS but have not been compared, and there is no consensus as to whether a beta-1 selective or nonselective beta blocker is superior in the treatment of POTS.

●  Side Effects: Can cause fatigue, headaches, or worsened lightheadedness in some patients, and if these occur, the medication is typically discontinued. May constrict airways in individuals with asthma; if cough or wheezing develop, it should be stopped. For mild asthma, an inhaled steroid may help patients tolerate atenolol. Also cause emotional depression but is less likely to cause nightmares, confusion, or hallucinations compared to other beta-blockers. It may interfere with the body’s ability to manage low blood sugar, so it should be used cautiously in diabetics because hypoglycemia can occur. Additionally, its effectiveness can be reduced when taken with NSAIDs like ibuprofen.

●  Dosage: The ideal dose for those with POTS is not well defined, and some authorities believe that lower doses may be preferable. The usual starting dose of atenolol for older adolescents and adults is 12.5-25 mg per day, but doses of up to 100 mg per day are used. The usual target is 1 mg per kg of body weight; for example, a person weighing 62 kg (136 lbs) would likely need 50-75 mg daily. Higher doses are less tolerated if the resting heart rate is below 50 bpm. Standard doses for other beta-blockers are: propranolol, 10–40 mg TID; bisoprolol, 2.5–5 mg BID; metoprolol, 25–100 mg daily; and atenolol, 12.5–50 mg daily.

● Reproductive and Pregnancy Considerations: Pregnancy data for propranolol, for example, shows no increased risk of teratogenicity, but it may be associated with neonatal apnea, respiratory distress, bradycardia, and hypoglycemia. The American Academy of Pediatrics classifies it as compatible with breastfeeding.

Citations

Deng, X., Zhang, Y., Liao, Y., & Du, J. (2019). Efficacy of β-Blockers on Postural Tachycardia Syndrome in Children and Adolescents: A Systematic Review and Meta-Analysis. Frontiers in pediatrics, 7, 460. https://doi.org/10.3389/fped.2019.00460

Raj, S. R., Black, B. K., Biaggioni, I., Paranjape, S. Y., Ramirez, M., Dupont, W. D., & Robertson, D. (2009). Propranolol decreases tachycardia and improves symptoms in the postural tachycardia syndrome: less is more. Circulation, 120(9), 725–734. https://doi.org/10.1161/CIRCULATIONAHA.108.846501

Fedorowski A. (2019). Postural orthostatic tachycardia syndrome: clinical presentation, aetiology and management. Journal of internal medicine, 285(4), 352–366. https://doi.org/10.1111/joim.12852

Moon, J., Kim, D. Y., Lee, W. J., Lee, H. S., Lim, J. A., Kim, T. J., Jun, J. S., Park, B., Byun, J. I., Sunwoo, J. S., Lee, S. T., Jung, K. H., Park, K. I., Jung, K. Y., Kim, M., Lee, S. K., & Chu, K. (2018). Efficacy of Propranolol, Bisoprolol, and Pyridostigmine for Postural Tachycardia Syndrome: a Randomized Clinical Trial. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, 15(3), 785–795. https://doi.org/10.1007/s13311-018-0612- 9

Vernino, S., Bourne, K. M., Stiles, L. E., Grubb, B. P., Fedorowski, A., Stewart, J. M., Arnold, A. C., Pace, L. A., Axelsson, J., Boris, J. R., Moak, J. P., Goodman, B. P., Chémali, K. R., Chung, T. H., Goldstein, D. S., Diedrich, A., Miglis, M. G., Cortez, M. M., Miller, A. J., Freeman, R., ... Raj, S. R. (2021). Postural orthostatic tachycardia syndrome (POTS): State of the science and clinical care from a 2019 National Institutes of Health Expert Consensus Meeting - Part 1. Autonomic neuroscience : basic & clinical, 235, 102828. https://doi.org/10.1016/j.autneu.2021.102828