Meta-analysis of T-T and T-T/QT ratio for risk stratification in congenital long QT syndrome.

BACKGROUND AND OBJECTIVES

Congenital long QT syndrome (LQTS) predisposes affected individuals to ventricular tachycardia/fibrillation (VF/VF), potentially resulting in sudden cardiac death. The T-T interval and the T-T/QT ratio, electrocardiographic markers of dispersion of ventricular repolarization, were proposed for risk stratification but their predictive values in LQTS have been controversial. A systematic review and meta-analysis was conducted to examine the value of T-T intervals and T-T/QT ratios in predicting arrhythmic and mortality outcomes in congenital LQTS.

METHOD

PubMed and Embase databases were searched until 9th May 2017, identifying 199 studies.

RESULTS

Five studies on long QT syndrome were included in the final meta-analysis. T-T intervals were longer (mean difference [MD]: 13ms, standard error [SE]: 4ms, P=0.002; I=34%) in congenital LQTS patients with adverse events [syncope, ventricular arrhythmias or sudden cardiac death] compared to LQTS patients without such events. By contrast, T-T/QT ratios were not significantly different between the two groups (MD: 0.02, SE: 0.02, P=0.26; I=0%).

CONCLUSION

This meta-analysis showed that T-T interval is significant higher in individuals who are at elevated risk of adverse events in congenital LQTS, offering incremental value for risk stratification.