Elsevier

Heart Rhythm

Volume 6, Issue 8, August 2009, Pages 1202-1208.e1
Heart Rhythm

Original-clinical
General
Predictive value of electrocardiographic QT interval and T-wave morphology parameters for all-cause and cardiovascular mortality in a general population sample

https://doi.org/10.1016/j.hrthm.2009.05.006Get rights and content

Background

The predictive value of ECG QT interval for mortality in the general population has been weak. Only a few population studies on the predictive value of ECG T-wave morphology parameters for mortality have been reported.

Objective

The purpose of this study was to examine the predictive value of ECG QT interval and T-wave morphology parameters for all-cause and cardiovascular mortality in the general population.

Methods

The prognostic values of ECG QT interval and four T-wave morphology parameters (principal component analysis ratio, T-wave morphology dispersion, total cosine R-to-T, T-wave residuum) were assessed in 5,917 adults (45% men; age 52 ± 14 years) participating in the Finnish population-based Health 2000 Study.

Results

After a mean follow-up of 5.9 ± 0.8 years, 335 deaths had occurred, including 131 cardiovascular deaths. QT interval and, with a few exceptions, all T-wave morphology parameters were significant univariate mortality predictors. In men, in Cox multivariate analyses, principal component analysis ratio and T-wave morphology dispersion remained as independent predictors of all-cause and cardiovascular mortality, with the above-median T-wave morphology dispersion group showing the highest risk of cardiovascular death (hazard ratio [HR] 4.4, 95% confidence interval [CI] 2.1−9.4). In women, independent mortality predictors were total cosine R-to-T (cardiovascular mortality) and T-wave residuum (all-cause and cardiovascular mortality), with the above-median T-wave residuum group showing the highest risk of cardiovascular death (HR 2.2, 95% CI 1.1−4.2).

Conclusion

In the general population, T-wave morphology parameters, but not heart rate-corrected QT interval, provide independent prognostic information on mortality. The prognostic value of T-wave morphology parameters is specifically related to cardiovascular mortality and seems to be gender specific.

Introduction

In patients with cardiovascular disease, abnormalities of ventricular repolarization on the electrocardiogram (ECG) are associated with cardiac morbidity and mortality; however, in the general population, the predictive value of heart rate-corrected QT interval for mortality has been weak.1, 2, 3, 4, 5 In recent years, computer-based analysis of digital ECG has produced new measures of ventricular repolarization, characterizing the three-dimensional morphology of the T wave.6, 7 These T-wave morphology parameters have been shown to provide prognostic information on survival in patients with cardiovascular disease as well as in patients with diabetes mellitus or end-stage renal disease.8, 9, 10, 11, 12, 13 Some evidence indicates that T-wave morphology parameters may contain prognostic information on mortality risk in the general population as well.7, 14, 15

The aim of this study was to explore the predictive value of T-wave morphology parameters for all-cause and cardiovascular mortality in the general population. The prespecified substudy of the Health 2000 Study provided high-quality digital ECGs and detailed clinical data from a large general population sample.16 We assessed ventricular repolarization using a set of four T-wave morphology parameters: principal component analysis ratio (PCA ratio, an estimate of T-wave complexity); T-wave morphology dispersion (TMD, an estimate of deviation between T waves); total cosine R-to-T (TCRT, an estimate of deviation between R and T waves); and T-wave residuum (TWR, an estimate of repolarization heterogeneity). We hypothesized that T-wave morphology parameters may provide independent prognostic information on all-cause and cardiovascular mortality in a large general population sample.

Section snippets

Study population and disease classification

The study population was derived from the Health 2000 Study, an epidemiologic survey that was conducted in Finland between fall 2000 and spring 2001. The study population, drawn from the Finnish Population Information System, was a two-stage stratified cluster sample of 8,028 Finnish adults aged ≥30 years. The Health 2000 Study consisted of a home interview, a comprehensive health examination including questionnaires, measurements (e.g., height, weight, blood pressure [BP], ECG), and a

Clinical data

Clinical characteristics of the study population are given in Table 1. Mean follow-up was 71 ± 9 months (5.9 ± 0.8 years). Of the 5,917 study subjects, 335 (5.7%) died during follow-up (9.6 deaths per 1,000 person-years of follow-up). Of all 335 deaths, 131 (39%) were cardiovascular deaths. In men, significant clinical predictors of all-cause and cardiovascular mortality were age, current smoking (all-cause mortality only), systolic BP, diastolic BP (all-cause mortality only), hypertension,

Main findings

In a large, population-based prospective study, ECG T-wave morphology parameters, but not heart rate-corrected QT interval, provide independent prognostic information specifically on cardiovascular mortality. T-wave morphology parameters show gender specificity in their performance, with PCA ratio and TMD in men as well as TWR in women providing the highest prognostic value.

QT interval as a mortality predictor in the general population

The T wave on the surface ECG is generated by myocardial voltage gradients during ventricular repolarization.24 Time from

Conclusion

In the general population, rate-adjusted QT interval and T-wave morphology parameters have predictive value for all-cause and cardiovascular mortality. However, when other risk factors of mortality are taken into account, T-wave morphology parameters, but not rate-adjusted QT interval, provide independent and thus potentially clinically useful risk assessment data for the general population. The independent prognostic value of these parameters is specifically related to cardiovascular mortality

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    This work was supported by grants to Dr. Porthan from the Aarne Koskelo Foundation, the Finnish Foundation for Cardiovascular Research, the Ida Montin Foundation, the Orion-Farmos Research Foundation, and the Paavo and Eila Salonen Foundation.

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