Authors: OKIN, PETER M.¹; MALIK, MAREK²; HNATKOVA, KATERINA²; LEE, ELISA T.³; GALLOWAY, JAMES M.⁴; BEST, LYLE G.⁵; HOWARD, BARBARA V.⁶; DEVEREUX, RICHARD B.¹

Source: Journal of Cardiovascular Electrophysiology, Volume 16, Number 9, September 2005 , pp. 945-951(7)

Publisher: Wiley-Blackwell

Abstract:

Repolarization Abnormality and Mortality.

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.

(J Cardiovasc Electrophysiol, Vol. 16, pp. 1-7, September 2005)

Keywords: electrocardiography; epidemiology; mortality; prognosis; repolarization; T-wave

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1540-8167.2005.40808.x

Affiliations: 1: Greenberg Division of Cardiology, Department of Medicine, Weill Medical College of Cornell University, New York, New York, USA 2: Cardiac and Vascular Sciences, St. George's Hospital Medical School, London, UK 3: College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA 4: University of Arizona, Tucson, Arizona, USA 5: Missouri Breaks Industries Research Inc., Timber Lake, South Dakota, USA 6: Medstar Research Institute, Washington, District of Columbia, USA

Publication date: 2005-09-01

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