Risk Factors for Severe Consequences of Long-QT Syndrome in Adolescents

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Risk Factors for Severe Consequences of Long-QT Syndrome in Adolescents

Beta-blocker therapy lowers risk.

The hereditary long-QT syndrome, with its prolonged ventricular repolarization, can lead to torsades de pointes, ventricular fibrillation, and sudden cardiac death. To identify factors associated with aborted cardiac arrest (requiring external defibrillation) and sudden cardiac death in adolescents with the syndrome, these authors analyzed data from the International Long QT Syndrome Registry for 2772 patients who were followed from age 10 to age 20 at five cardiac centers in the U.S. and Europe. The study was partly funded by a pharmaceutical company.

Overall, 81 patients had aborted cardiac arrests, and 54 experienced sudden cardiac death; 9 of the patients with aborted cardiac arrest subsequently experienced sudden cardiac death. The authors identified three independent risk factors for aborted cardiac arrest and sudden cardiac death (together termed life-threatening events): syncope, prolonged QTc, and male sex. The adjusted hazard ratios for the risk factors are as follows (see Table 1):

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Table 1: Risk for Life-Threatening Events

There was no significant difference in risk for life-threatening events between males and females aged 13 to 20.

Comment: This study is the largest to date on long-QT syndrome and the first to report risk factors for life-threatening events. Of note, ß-blocker therapy in patients who had syncope during the previous 2 years reduced the risk for aborted cardiac arrest or sudden cardiac death by 64%.

— John A. Marx, MD, FAAEM, FACEP

Published in Journal Watch Emergency Medicine October 27, 2006