Electrocardiographic QT Interval and Mortality

Abstract

Background Extremely abnormal prolongation of the electrocardiographic QT interval is associated with malignant ventricular arrhythmias and sudden cardiac death. However, the implications of variations in QT-interval length within normal limits for mortality in the general population are still unclear. Methods We performed a meta-analysis to investigate the relation of QT interval with mortality endpoints. Inverse-variance weighted random-effects models were used to summarize the relative risks across studies. Twenty-three observational studies were included. Results The pooled relative risk estimates comparing the highest with the lowest categories of QT-interval length were 1.35 (95% confidence interval = 1.24–1.46) for total mortality, 1.51 (1.29–1.78) for cardiovascular mortality, 1.71 (1.36–2.15) for coronary heart disease mortality, and 1.44 (1.01–2.04) for sudden cardiac death. A 50 msec increase in QT interval was associated with a relative risk of 1.20 (1.15–1.26) for total mortality, 1.29 (1.15–1.46) for cardiovascular mortality, 1.49 (1.25–1.76) for coronary heart disease mortality, and 1.24 (0.97–1.60) for sudden cardiac death. Conclusions We found consistent associations between prolonged QT interval and increased risk of total, cardiovascular, coronary, and sudden cardiac death. QT-interval length is a determinant of mortality in the general population.

Cardiac Potassium Channel Subtypes: New Roles in Repolarization and Arrhythmia

“…Its prolongation has been associated with an increased risk of sudden cardiac death (494), although its predictive value for ventricular arrhythmia is debated and the concept of TRIaD (triangulation, reverse use depen-dence, instability and dispersion) has been suggested (184,186,187). However, there is increasing evidence that prolongation of the mean QT interval is associated with AF (330).…”

O5‐06‐06: Changes in QTC Interval in the Citalopram for Agitation in Alzheimer's Disease (Citad) Randomized Trial

“…Extreme QTc prolongation (QTc.500 milliseconds) can result in electrical instability during repolarization, increasing the risk of polymorphic ventricular tachycardia (Torsade de pointes; TdP) and sudden cardiac death [4,5]. A review of the literature found consistent associations between prolonged QTc and death in high risk populations [6] and a meta-analysis of observational data found that the pooled estimates support associations between prolonged QTc and death in the general population [7]. Although QT prolongation can be caused by heritable disorders in cardiac ion channel expression, numerous marketed drugs are also known to lengthen the QT interval (QTdrugs.org) in people without genetic abnormalities.…”

Prolonged QTc Interval Predicts Poststroke Paroxysmal Atrial Fibrillation

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