What is the role of beta-blockers in the treatment of long QT syndrome (LQTS)?

Updated: Nov 29, 2017
  • Author: Ali A Sovari, MD, FACP, FACC; Chief Editor: Mikhael F El-Chami, MD  more...
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Answer

Beta-blockers are effective in preventing cardiac events in approximately 70% of patients with long QT syndrome (LQTS), whereas cardiac events continue to occur despite beta-blocker therapy in the remaining 30%.

Propranolol and nadolol are the most frequently used beta-blockers, although atenolol and metoprolol are also prescribed in patients with LQTS. Different beta-blockers demonstrate similar effectiveness in preventing cardiac events in patients with LQTS. Nadolol is effective for reducing cardiac events in patients with LQT1 and in those with LQT2, whereas atenolol and propranolol appear to decrease this risk only for LQT1, and metoprolol does not appear to have any significant risk reduction for LQT1 or LQT2. [26] Beta-blocker therapy may not be as effective for LQT3 as for LQT1 or LQT2, but there are not enough data to make a more conclusive assessment. [26]

Response to beta-blocker therapy may also vary depending on the triggering event. A study by Goldenberg et al found that in patients with LQT1, beta-blocker therapy is effective when exercise triggers the event, but it is ineffective if the event happens during sleep or arousal. [27]

Koponen et al collected follow-up data, covering a mean of 12 years, for 316 genotyped LQT1 and LQT2 patients aged 0 to 18 years. In this pediatric group of genotyped and appropriately treated LQTS patients, they found that severe cardiac events were uncommon. [28]  In addition, treatment with beta-blocker medications reduced the risk of cardiac events and was generally well tolerated.

Previously, the recommended dosage of beta-blockers was relatively large (eg, propranolol 3 mg/kg/day, or 210 mg/day in a 70-kg individual); more recent data suggest that lower dosages have a protective effect similar to that of large dosages.


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