Abstract 14975: Risk Stratification in Long Qt Syndrome Patients With Very Prolonged Qtc Interval
Introduction: Long QT (LQT) syndrome patients with very prolonged QTc interval are at increased risk for worsened outcomes. We aimed to identify risk factors associated with adverse cardiac events in this group.
Methods: We studied 673 patients from the Rochester, New York LQT syndrome registry with very prolonged QTc interval, defined as QTc>500 msec. Genotype data were available for 345 patients. Follow-up began after initial ECG and continued till age 50 years. Primary end point was any first cardiac event, consisting of syncope, aborted cardiac arrest, implantable cardioverter-defibrillator shock, and death. Secondary end point included only life-threatening cardiac events.
Results: During mean follow-up of 11.0±8.1 years, crude rate of cardiac events was 32%. Clinical variables associated with primary end point were female gender aged>13 years compared to male gender aged>13 years (HR=1.89, 95% CI: 1.20-1.29, p<0.01) and prior syncope (HR=2.05, 95% CI: 1.49-2.82, p<0.001). Beta-blockers were significantly protective (HR=0.64, 95% CI=0.48-0.87, p=0.008). Importantly, QTc duration as a continuous variable (HR=1.01, 95% CI=0.98-1.04, p=0.432) and genotype (LQT2 vs. LQT1: HR=1.13, 95% CI: 0.72-1.75, p=0.574, LQT3 vs. LQT1: HR=1.17, 95% CI: 0.62-1.21, p=0.640, LQT3 vs. LQT2: HR=1.03, 95% CI: 0.54-1.95, p=0.931) were not predictive of CEs. Similar results were observed for the secondary end point.
Conclusions: Among LQT syndrome patients with very prolonged QTc interval, only history of syncope, gender and age identified patients at risk for cardiac events. However, QTc duration and genotype were not predictive of outcomes. Beta-blockers are protective even in this high-risk group.
Author Disclosures: Y. Biton: None. U. Daimee: None. A. Moss: Research Grant; Significant; grant support from Boston Scientific. W. Zareba: Research Grant; Significant; grant support from Boston Scientific. V. Kutyifa: Research Grant; Significant; grant support from Boston Scientific. S. Mcnitt: None. B. Polonsky: None. I. Goldenberg: Research Grant; Significant; grant support from Boston Scientific.
- © 2016 by American Heart Association, Inc.