Abstract 9368: Long QT Syndrome and Therapy for Attention Deficit/Hyperactivity Disorder

Abstract

Objective: This study was designed to investigate the clinical course of patients with long QT syndrome (LQTS) who are treated for attention deficit/hyperactivity disorder (ADHD) with medications. Background: Current literature on the effect of ADHD treatment on the clinical outcome of LQTS patients is limited. We hypothesized that LQTS patients on ADHD pharmacotherapy, which has known adrenergic side effects, would be at increased risk for cardiac events. Methods: Patients in this study were from the Rochester-based LQTS Registry. LQTS patients being treated with stimulant or non-stimulant ADHD medications (n=48) were compared to a 2:1 age-, gender-, and QTc-duration matched LQTS control group not exposed to ADHD medications (n=96). Kaplan-Meier and Cox proportional hazards regression analyses were used to evaluate risk of cardiac events (syncope, aborted cardiac arrest, and sudden cardiac death) in LQTS patients treated with ADHD medications compared to those who were not. Results: During a mean follow-up of 7.9 ±5.4 years of follow-up after initiation of ADHD medication at a mean age 10.7 ±7.3 years, there was a 62% cumulative probability of cardiac events in the ADHD treatment group compared to 28% in the matched LQTS control group (p<0.001 [Figure]). Time-dependent use of stimulant and non-stimulant ADHD medication was associated with an increased risk for cardiac events dominated by syncope (HR=3.07; 95% CI 1.09-8.64; p=0.03) in the multivariate Cox model adjusted for time-dependent β-blocker use and prior cardiac events. Subgroup gender analyses showed that time-dependent ADHD medication was associated with an increased risk in male LQTS patients (HR=6.80, p=0.04). Conclusion: LQTS patients treated with ADHD medications have an increased risk for cardiac events during follow-up, and this risk is augmented in males.