Effectiveness and limitations of beta-blocker therapy in congenital long-QT syndrome.

Abstract

BACKGROUND:

beta-blockers are routinely prescribed in congenital long-QT syndrome (LQTS), but the effectiveness and limitations of beta-blockers in this disorder have not been evaluated.

METHODS AND RESULTS:

The study population comprised 869 LQTS patients treated with beta-blockers. Effectiveness of beta-blockers was analyzed during matched periods before and after starting beta-blocker therapy, and by survivorship methods to determine factors associated with cardiac events while on prescribed beta-blockers. After initiation of beta-blockers, there was a significant (P<0.001) reduction in the rate of cardiac events in probands (0.97+/-1.42 to 0.31+/-0.86 events per year) and in affected family members (0. 26+/-0.84 to 0.15+/-0.69 events per year) during 5-year matched periods. On-therapy survivorship analyses revealed that patients with cardiac symptoms before beta-blockers (n=598) had a hazard ratio of 5.8 (95% CI, 3.7 to 9.1) for recurrent cardiac events (syncope, aborted cardiac arrest, or death) during beta-blocker therapy compared with asymptomatic patients; 32% of these symptomatic patients will have another cardiac event within 5 years while on prescribed beta-blockers. Patients with a history of aborted cardiac arrest before starting beta-blockers (n=113) had a hazard ratio of 12.9 (95% CI, 4.7 to 35.5) for aborted cardiac arrest or death while on prescribed beta-blockers compared with asymptomatic patients; 14% of these patients will have another arrest (aborted or fatal) within 5 years on beta-blockers.

CONCLUSIONS:

beta-blockers are associated with a significant reduction in cardiac events in LQTS patients. However, syncope, aborted cardiac arrest, and LQTS-related death continue to occur while patients are on prescribed beta-blockers, particularly in those who were symptomatic before starting this therapy.

• Authors: A J Moss, W Zareba, W J Hall, P J Schwartz, R S Crampton, J Benhorin, G M Vincent, E H Locati, S G Priori, C Napolitano, A Medina, L Zhang, J L Robinson, K Timothy, J A Towbin, M L Andrews
• Journal: Circulation (Circulation) Vol. 101 Issue 6 Pg. 616-23 (Feb 15 2000) ISSN: 1524-4539 [Electronic] United States
• PMID: 10673253 (Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Adrenergic beta-Antagonists
• Nadolol
• Atenolol
• Propranolol
• Metoprolol

Topics

• Adolescent
• Adrenergic beta-Antagonists (administration & dosage, adverse effects)
• Adult
• Atenolol (administration & dosage, adverse effects)
• Child
• Child, Preschool
• Female
• Humans
• Infant
• Long QT Syndrome (congenital, drug therapy, physiopathology)
• Male
• Metoprolol (administration & dosage, adverse effects)
• Nadolol (administration & dosage, adverse effects)
• Propranolol (administration & dosage, adverse effects)
• Survival Analysis