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Meta-Analysis
. 2011 Sep;22(5):660-70.
doi: 10.1097/EDE.0b013e318225768b.

Electrocardiographic QT interval and mortality: a meta-analysis

Yiyi Zhang  1 , Wendy S Post, Elena Blasco-Colmenares, Darshan Dalal, Gordon F Tomaselli, Eliseo Guallar
Affiliations
Meta-Analysis

Electrocardiographic QT interval and mortality: a meta-analysis

Yiyi Zhang et al. Epidemiology. 2011 Sep.

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 milliseconds 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.

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Figures

Figure 1
Figure 1. Flow diagram of study selection process
Figure 2
Figure 2. QT metric and interval cutpoints used in the original studies
Solid lines represent studies reporting categorical QT intervals. The triangles represent the cutpoints used in the original studies, and the bold segments represent the reference category originally used in each study. (In this meta-analysis we recalculated the results so that the reference category used in the meta-analysis was the lowest QT interval category). Dotted lines represent studies using QT-interval length as a continuous variable. Stars represent median QTc intervals instead of mean intervals.
Figure 3
Figure 3. Meta-analysis of the association of increased QT-interval length with mortality endpoints
Relative risks (RRs) correspond to comparisons of the highest vs. the lowest reported category of QT-interval length in studies that categorized QT interval or to the RR for mortality associated with an increase in 50 ms in QT interval length in studies that used QT interval length as a continuous variable. The area of each square is proportional to the inverse of the variance of the log RR. Horizontal lines represent 95% CIs. Diamonds represent pooled estimated from inverse-variance weighted random effects models.
Figure 4
Figure 4. Dose-response meta-analysis of QT-interval length and mortality endpoints
Circle areas are inversely proportional to the variance of the log relative risks from studies using categorical QT intervals. Dashed lines correspond to studies that used QT-interval length as a continuous variable. The pooled linear risk trend (thick solid line) and its 95% confidence band (shaded region) were obtained using a random-effects dose-response meta-analysis.
See this image and copyright information in PMC

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