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


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.
Moss
A J
AJ
Department of Medicine, University of Rochester School of Medicine and Dentistry, NY 14642, USA. heartajm@heart.rochester.edu
Zareba
W
W
Hall
W J
WJ
Schwartz
P J
PJ
Crampton
R S
RS
Benhorin
J
J
Vincent
G M
GM
Locati
E H
EH
Priori
S G
SG
Napolitano
C
C
Medina
A
A
Zhang
L
L
Robinson
J L
JL
Timothy
K
K
Towbin
J A
JA
Andrews
M L
ML
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D000328:Adult; D001262:Atenolol / Q000008:administration & dosage / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008133:Long QT Syndrome / Q000151:congenital / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000009:adverse effects; D009248:Nadolol / Q000008:administration & dosage / Q000009:adverse effects; D011433:Propranolol / Q000008:administration & dosage / Q000009:adverse effects; D016019:Survival Analysis
D000319:Adrenergic beta-Antagonists; D009248:Nadolol; D001262:Atenolol; D011433:Propranolol; D008790:Metoprolol