Repolarization abnormality for prediction of all-cause and cardiovascular mortality in American Indians: the Strong Heart Study

J Cardiovasc Electrophysiol. 2005 Sep;16(9):945-51. doi: 10.1111/j.1540-8167.2005.40808.x.


Background: Analysis of electrocardiographic (ECG) repolarization abnormality using QTc interval and principal component analysis (PCA) of the T-wave vector predict all-cause and cardiovascular (CV) mortality. Novel descriptors of T-wave morphology have been suggested as measures of repolarization heterogeneity and adverse prognosis. However, whether these T-wave descriptors provide prognostic information beyond QTc and the PCA ratio has not been examined.

Methods and results: Predictive values of QTc, PCA, and novel ECG variables characterizing the T-wave loop were assessed in 1,729 American Indian participants in the first Strong Heart Study exam. T-loop morphology was quantified by the ratio of the second to first eigenvalues of the T-wave vector (PCA ratio), T-loop area (TLA) projected onto the dominant vector plane, T-wave morphology dispersion (TMD) and by the sum of the squares of the fourth to eighth eigenvalues, the T-wave residuum (TWR). After mean follow-up of 4.8 +/- 0.8 years, there were 183 deaths from all causes, including 51 CV deaths. In univariate Cox analyses, prolonged QTc, increased PCA ratio, TLA, TMD, and TWR were significant predictors of all-cause and CV mortality (P < 0.001). In multivariate Cox analyses adjusting for demographic and clinical risk factors for mortality, increased PCA ratio (chi-square = 7.9, P = 0.005) and TWR (chi-square = 5.3, P = 0.022) remained significant predictors of CV mortality and increased QTc (chi-square = 12.1, P < 0.001) and TWR (chi-square = 6.0, P = 0.014) of all-cause mortality. Addition of TWR to the model with clinical variables and the PCA ratio for CV mortality and to the model with clinical variables and prolonged QTc for all-cause mortality increased prognostic value of each model (increase in overall chi-square from 287.5 to 301.9 and from 221.5 to 230.3, respectively).

Conclusion: Novel descriptors of T-wave complexity provide additional prognostic information beyond QTc and PCA ratio for prediction of all-cause and CV mortality.

Publication types

  • Clinical Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Arrhythmias, Cardiac / diagnosis
  • Arrhythmias, Cardiac / mortality
  • Cardiovascular Diseases / diagnosis*
  • Cardiovascular Diseases / ethnology
  • Cardiovascular Diseases / mortality*
  • Diagnosis, Computer-Assisted / methods*
  • Electrocardiography / methods*
  • Female
  • Humans
  • Indians, North American / statistics & numerical data*
  • Male
  • Middle Aged
  • Prevalence
  • Principal Component Analysis
  • Prognosis
  • Reproducibility of Results
  • Risk Assessment / methods*
  • Risk Factors
  • Sensitivity and Specificity
  • Survival Analysis
  • Survival Rate
  • United States / epidemiology