# Long-term fate of long QT syndrome patients diagnosed in childhood and differential effects of beta-blockers

## TL;DR

This study examines the long-term outcomes of children diagnosed with long QT syndrome and finds that non-selective beta-blockers are more effective in reducing arrhythmic events.

## Contribution

The study provides evidence that non-selective beta-blockers reduce the burden of major arrhythmic events more effectively than selective ones in pediatric LQTS patients.

## Key findings

- 20-year survival probability was 90.2% for LQTS patients treated with beta-blockers.
- Non-selective beta-blockers significantly reduced the cumulative burden of major arrhythmic events.
- Early presentation and LQTS type 3 were strong predictors of major arrhythmic events.

## Abstract

Congenital long QT syndrome (LQTS) is associated with the risk of major arrhythmic events (MAEs), which can be modified by beta-blocker (BB) administration. We aimed to evaluate the effects of selective vs. non-selective BBs on the cumulative burden of MAEs by performing a retrospective analysis of a cohort of LQTS patients diagnosed during childhood.

All pediatric patients (N = 179, female 54.7%) without structural heart disease diagnosed with LQTS (Schwartz score ≥3.5 points and/or presence of a pathogenic or likely pathogenic genetic variant) between 1985 and 2022, with a median presentation age of 10.8 and a median follow-up of 8.5 years, were included. Data were obtained from medical records, structured patient phone calls, and the National Death Registry.

Mean QTc and median Schwartz score were 501.20 ms and 4.0 points, respectively. Pathogenic or likely pathogenic variants were identified in 124 of 143 tested patients (86.7%). BBs were administered to 156 patients (87.2%). Eleven patients died (6.1%), yielding survival probabilities at 5/10/20 years of 97.7%/94.0%/90.2%. Freedom from MAEs was 93.9%/89.4%/79.3% at 5/10/20 years. MAE was independently predicted by early presentation [hazard ratio (HR): 6.92, p < 0.001], Schwartz score (HR: 1.87, p < 0.002), QTc (HR: 1.13, p < 0.001), and the presence of LQTS type 3 (HR: 7.91, p < 0.001). MAE burden was significantly lower in patients treated with non-selective vs. selective BBs, independent of other risk-determining variables (Poisson regression model p = 0.011).

The 20-year survival probability of patients with LQTS diagnosed during childhood was 90.2% in the BB treatment era. Non-selective BBs were significantly more effective in decreasing the cumulative MAE burden.