Effectiveness and Limitations of β-Blocker Therapy in Congenital Long-QT Syndrome
To the Editor:
In a recent issue of Circulation, Moss and colleagues1 report their analysis of β-blocker therapy in patients from the International Long-QT Syndrome Registry. They demonstrated that β-blockers significantly reduced cardiac events but that 32% of patients who were symptomatic before initiating therapy had further cardiac events within 5 years. In addition, Moss et al1 did not find a relationship between the dose of β-blockers and cardiac event rate reduction. The findings in this report raise important questions.
For example, what is treatment success and what is the appropriate response to a cardiac event in a patient on β-blockers? If the goal is to have no cardiac-related events, then any event should be considered a treatment failure, a cause should be sought, and action should be taken. If it were believed that no further benefit could be expected from a dosage increase (either an apparent maximal effect already or a lack of evidence for improved efficacy with higher doses), then should not a further treatment modality be introduced? This action may be to change medications, insert a pacemaker or defibrillator, or perform a sympathetic ganglionectomy. Whatever the choice, only rare circumstances should result in no change in management. With this in mind, what was the response to a clinical event in the symptomatic patients described in this report? How many, if any, had no change in therapy? Was further recurrence of cardiac-related events different in patients who had management changes than in those who did not have any therapy change? Were the authors able to determine the impact on the event rate of any additional therapies, such as rate maintenance with pacing? These issues must be clarified if clinical management decisions are to be informed further by this article.1 We may then know what impact our own management strategies have on the potential effectiveness of β-blockers in patients with congenital long-QT syndrome.
- Copyright © 2001 by American Heart Association