Intentional nontherapy in long QT syndrome

Background: International guidelines advise universal beta-blocker therapy as either a class I (symptomatic or QTc ≥470 ms) or class II (asymptomatic and QTc <470 ms) recommendation for treatment of long QT syndrome (LQTS).

Objective: The purpose of this study was to evaluate the outcomes of a highly selected cohort of patients with LQTS managed with an observation-only (intentional nontreatment) strategy.

Methods: The cohort was derived from a comprehensive retrospective registry of patients with LQTS. Clinical phenotype and genotype data were collected via review of electronic health records.

Results: Among 661 patients with LQTS, 55 (8.3%) asymptomatic patients (53% female; 16 age <18 years) were managed with intentional nontherapy. Only preventative measures were advised. Mean age at diagnosis was 37.8 ± 21.2 years. Mean QTc was 448 ± 30 ms. None of the patients experienced an LQTS-triggered cardiac event over mean follow-up of 7.5 ± 4.3 years. Compared to the larger treated cohort, this intentionally untreated cohort was less symptomatic, was older at diagnosis, and had lower resting QTc values (P <.0001).

Conclusion: After careful clinical evaluation, risk assessment, and institution of precautionary measures, an observation-only strategy may be considered in a highly selected group of LQTS patients with a clinical profile that includes asymptomatic status, older age at diagnosis, and QTc <470 ms, with excellent outcomes and better quality of life than LQTS patients treated with beta-blocker. LQTS patients with this low-risk profile should not receive a prophylactic implantable cardioverter-defibrillator.